DEGREE PROJECT IN MECHANICAL ENGINEERING, SECOND CYCLE, 30 CREDITS STOCKHOLM, SWEDEN 2018
Implementing Design For Automatic Assembly A recommendation on how to implement and apply DFAA at Company Y
FILIPPA VON YXKULL
KTH ROYAL INSTITUTE OF TECHNOLOGY SCHOOL OF INDUSTRIAL ENGINEERING AND MANAGEMENT
Implementing Design For Automatic
Assembly
A recommendation on how to implement and apply DFAA at Company Y
Filippa von Yxkull
Master of Science Thesis TPRMM: 2018: KTH Production Engineering and Management Industrial Production SE-100 44 STOCKHOLM
Abstract
The need to work with Design for Automatic Assembly (DFAA) has been widely recognized in the literature. However, the implementation of DFAA is not clearly defined. Therefore, the purpose of this master thesis is to investigate and contribute with knowledge of how DFAA should be implemented into an organization, such as Company Y.
Several interviews have been conducted to establish a current state analysis, to receive an understanding of the current problems at Company Y and how to address them. A benchmarking study was conducted, where the three companies Ericsson, Company X and Scania were interviewed. All three companies have successfully implemented DFA and were interviewed with the purpose to obtaining their best practices. The study also included an early implementation of DFAA, where a software based DFA2-method created by Eskilander (2001) was tested on a current product and a new developed design concept at Company Y. Based on this a recommended workflow of the evaluation could be attained.
Based on the empirical gatherings several recommendations of how DFAA should be implemented into the organization could be made. The study highlights that DFAA should be applied as early as possible in the product development process. The DFA2-method should be utilized at product level to facilitate concept selection and at part level to make the products/modules suited for automatic assembly, before the design is “locked” and before a physical prototype is created. The departments that should be working with DFAA includes individuals from production, design quality and purchasing. However, once DFA becomes rooted in the company, more functions in the company’s supply chain will become affected. This means that more functions might need to be included in the work of DFAA. Finally, the study includes a decision model, in which the decisions are based on the measurable values received from the DFA2-method.
Key words: DFAA, DFA, Product design, Assembly process, assemblability
I Sammanfattning
Behovet av att arbeta med Design for Automatic Assembly (DFAA) har uppmärksammat i litteraturen. Däremot har implementeringen av DFAA inte blivit tydligt definierat. Syftet med detta examensarbete blir således att undersöka och bidra med kunskap om hur DFAA ska implementeras i en organisation, så som Företag Y.
Flera intervjuer har genomförts för att upprätta en nuvarandeanalys för att få förståelse för de rådande problemen hos Company Y och hur dessa ska hanteras. En benchmarkingstudie genomfördes, där de tre företagen Ericsson, Company X och Scania intervjuades. Alla tre företagen har framgångsrikt implementerat DFA och har intervjuats med syftet att erhålla deras bästa praxis. Studien innefattar även en tidig implementering av DFAA, där en mjukvarubaserad DFA2-metod skapad av Eskilander (2001), har testats på en aktuell produkt och ett nytt utvecklat koncept på Company Y. Baserat på detta kunde ett rekommenderat arbetsflöde av utvärderingen presenteras.
Baserat på empiriska studien kunde flera rekommendationer gällande hur DFAA ska implementeras i en organisation skapas. Studien belyser att DFAA bör tillämpas så tidigt som möjligt i produktutvecklingsprocessen. DFA2-metoden bör utnyttjas på produktnivå för att underlätta konceptvalet och på komponentnivå för att göra produkterna/modulerna lämpade för automatisk montering, detta innan designen är "låst" och innan en fysisk prototyp har konstruerats. Avdelningar som ska arbeta med DFAA inkluderar produktion, designkvalitet och inköp. När DFA blir rotad i företaget kommer dock fler funktioner i företagets supply chain att påverkas. Det innebär att fler funktioner kan behöva inkluderas med arbetet kring DFAA. Slutligen så inkluderar studien en beslutsmodell relaterat till DFAA. Besluten baseras på de mätbara värden från DFA2-metoden.
Nyckelord: DFA, DFAA, produkt design, monteringsprocess, monterbarhet
II Table of contents Abstract ...... I Sammanfattning ...... II 1. Introduction ...... 1 1.1 Background ...... 1 1.2 Problem Formulation ...... 2 1.3 Purpose & Research Question ...... 2 1.4 Delimitations ...... 3 1.5 Study’s Expected Contribution ...... 3 1.6 Disposition ...... 4 2. Literature & Theory ...... 5 2.1 Definitions ...... 5 2.1.1 Assembly ...... 5 2.1.2 Concurrent engineering ...... 6 2.1.3 DFX ...... 6 2.1.4 DFA ...... 7 2.2 DFA methods ...... 9 2.2.1 Boothroyd’s & Dewhurst’s DFMA Method ...... 10 2.2.2 DFA2, Design For Automatic Assembly method ...... 12 2.3 Implementation of DFA ...... 16 2.4 Impact DFA has on the future of manufacturing ...... 19 2.4.1 Modularity in respect to DFA ...... 19 2.4.2 Evolvable assembly systems ...... 21 3. Method ...... 22 3.1 Research Design & process ...... 22 3.2 Primary Sources ...... 23 3.2.1 Pre-study ...... 23 3.2.2 Interviews ...... 23 3.2.3 Observations ...... 25 3.2.4 Early implementation of DFA2 ...... 25 3.3 Secondary Sources ...... 26 3.4 Quality of Analysis ...... 27 3.4.1 Reliability ...... 27 3.4.2 Validity ...... 28 3.5 Ethical considerations ...... 28 4. Benchmarking ...... 30 4.1 Ericsson ...... 30 4.1.1 Reasons for working with DFA ...... 30 4.1.2 Choice of DFA method ...... 31 4.1.3 Departments working with DFA ...... 31 4.1.4 Workflow- DFA analysis ...... 32 4.1.5 DFA in the development process ...... 33 4.1.6 Implementation ...... 36 4.1.7 Decisions model regarding DFA ...... 36 4.1.8 DFA initiator ...... 36 4.2 Company X ...... 37 4.2.1 Reasons for working with DFA ...... 37 4.2.2 DFA Method ...... 37
III 4.2.3 Departments working with DFA ...... 37 4.2.4 Workflow of DFA analysis ...... 38 4.2.5 Implementation ...... 39 4.2.6 DFA in the product development process ...... 39 4.2.7 Decision model regarding DFA ...... 40 4.2.8 DFA initiator ...... 40 4.3 Scania ...... 41 4.3.1 Reasons for working with DFA ...... 41 4.3.2 Choice of method ...... 41 4.3.3 Workflow- DFA analysis ...... 43 3.3.4 Implementation ...... 43 4.3.5 DFA in the development process ...... 43 4.3.6 Decision model regarding DFA ...... 44 5. Current state analysis ...... 45 5.1 Company description ...... 45 5.2 Reasons for working with DFA ...... 45 5.3 current way of working with ease for assembly ...... 45 5.3.1 Design Reviews ...... 46 5.3.2 Automation workshops ...... 46 5.3.3 AviX - DFX ...... 47 5.3.4 The DFAA Project ...... 47 5.3.5 Modularisation ...... 47 5.4 DFA in the Product development process ...... 47 5.4.1 Gate model ...... 47 5.4.2 The checklist ...... 48 5.5 Decision making ...... 49 5.6 Challenges to Implementing DFA ...... 49 6. Results & Analysis ...... 50 6.1 Application of the DFA2-method ...... 50 6.1.1 Workshop- early implementation ...... 50 6.1.2 Advantages with the DFA2-method ...... 54 6.1.3 Drawbacks with the DFA2-method ...... 55 6.1.4 Recommended Workflow ...... 56 6.2 Departments working with DFAA ...... 57 6.3 DFAA in the development process ...... 58 6.4 Decision model regarding DFAA ...... 59 6.5 Implementation plan ...... 61 7. Discussion ...... 63 8. Conclusions ...... 64 7.1 Concluding the research questions ...... 64 7.2 Limitations ...... 66 7.3 Implications ...... 66 7.3.1 Theoretical implications ...... 67 7.3.2 Managerial implications ...... 67 7.4 Future work ...... 68 References ...... 69 Appendix A: Interview Guide – Company Y ...... 72 Appendix B: Gantt-chart ...... 75
IV Abbreviations
In this section, the abbreviations and glossary for terms commonly used throughout the master thesis will be displayed.
Abbreviations
CE Concurrent Engineering
DFX Design for X
DFAA Design For Automatic Assembly
DFMA Design For Manufacture and Assembly
DFA2-index Design For Automatic Assembly Index
CAD Computer-aided Design
BOM Bill Of Material
R&D Research and Development
MFD Modular Functional Deployment
FMEA Failure Modes and Effects Analysis
Glossary
DFA2 The method within the area of DFAA
V Figures & Tables
This section states the figures and tables that were included in the master thesis.
Figures FIGURE 1 ILLUSTRATION OF THE STRUCTURE OF THE MASTER THESIS ...... 4 FIGURE 2 ILLUSTRATION FROM (BOOTHROYD, DEWHURST AND KNIGHT, 2011) DISPLAYING THE "OVER THE WALL" APPROACH...... 6 FIGURE 3 ILLUSTRATION FROM (ESKILANDER, 2001) DISPLAYING THE HIERARCHICAL STRUCTURE OF DFX...... 7 FIGURE 4 TABLE OF THE MOST COMMON COMMERCIAL DFA METHODS (ESKILANDER, 2001) ...... 9 FIGURE 5 ILLUSTRATION OF DFMA SOFTWARE, DFA PRODUCT SIMPLIFICATION (DFMA.COM,2018) ...... 12 FIGURE 6 GUIDELINES FOR PRODUCT LEVEL AND PART LEVEL (ESKILANDER, 2001) ...... 13 FIGURE 7 SNAPSHOT OF THE DFX MODULE PROVIDED BY AVIX (AVIX.EU, 2018) ...... 14 FIGURE 8 ILLUSTRATION OF THE VISUAL AIDS PROVIDED BY AVIX (AVIX.EU, 2018) ...... 15 FIGURE 9 RESULT OF AN DFA2-ANALYIS ON PART LEVEL...... 15 FIGURE 10 ILLUSTRATION OF TIME SAVINGS ACHIEVED BY IMPLEMENTING DFMA (BOOTHROYD, DEWHURST AND KNIGHT, 2011). . 19 FIGURE 11 FACTORIES WITHIN THE FACTORY (ERICSSON AND ERIXON, 1999) ...... 20 FIGURE 12 ILLUSTRATION OF THE STUDY’S RESEARCH PROCESS ...... 23 FIGURE 13 ILLUSTRATION OF THE FLOW CHART OF THE LITERATURE SEARCH (COLLIN AND HUSSEY, S. 82, 2014) ...... 27 FIGURE 14 SNAPSHOT OF ACTION LIST (ULIN, 2018) ...... 33 FIGURE 15 DFA IN ERICSSON’S DESIGN PROCESS ...... 34 FIGURE 16 DFA IN THE DESIGN PROCESS ...... 35 FIGURE 17 ILLUSTRATION OF THE AP-LIST MEASUREMENT ...... 36 FIGURE 18 ILLUSTRATION OF THE PRODUCT DEVELOPMENT PROCESS AT COMPANY X ...... 40 FIGURE 19 ILLUSTRATION OF A SNAPSHOT OF THE DFA CHECKLIST AT SCANIA (HOLMER 2018) ...... 41 FIGURE 20 ILLUSTRATION OF SCANIA’S INTERNAL WIKI (KLINGNELL, 2014)...... 42 FIGURE 21 ILLUSTRATION OF SCANIA’S PRODUCT DEVELOPMENT PROCESS ...... 44 FIGURE 23 COMPANY Y’S PRODUCT DEVELOPMENT PROCESS (INTRANET, 2018)...... 47 FIGURE 25 EVALUATION OF CURRENT DESIGN OF THE MECHANICAL COMPONENT ...... 53 FIGURE 26 RESULTS OF THE NEW DESIGN CONCEPT ...... 54 FIGURE 27 ILLUSTRATION OF THE CRITERIA “WHEN VISION IS NEEDED” ...... 55 FIGURE 28 DFAA IN COMPANY Y’S PRODUCT DEVELOPMENT PROCESS ...... 59 FIGURE 29 REGRESSION ANALYSIS (SOLME, N.D) ...... 60 FIGURE 30 RECOMMENDATION OF A DECISION MODEL REGARDING DFAA ...... 61 FIGURE 31 RECOMMENDATION OF A DECISION MODEL REGARDING DFAA ...... 66
Tables TABLE 1 RECORD OF ALL THE INTERVIEWS, MEETINGS AND OTHER ACTIVITIES HELD DURING THE THESIS...... 24 TABLE 2 ERICSSON’S DESIGN PROCESS ...... 33 TABLE 3 LIST OF THE PARTS IN THE CURRENT DESIGN OF THE SUBASSEMBLY OF THE MECHANICAL COMPONENT ...... 51 TABLE 4 LIST OF THE ASSEMBLY ORDER OF THE CURRENT DESIGN...... 52 TABLE 5 LIST OF THE PARTS IN THE NEW DESIGN OF THE SUBASSEMBLY OF THE MECHANICAL COMPONENT...... 53
VI
Foreword & Acknowledgements
This master thesis was conducted in collaboration with Company Y. The project is completing my master in Production Engineering and Management at KTH, Royal Institute of Technology. The study was conducted in the spring of 2018, Stockholm, Sweden and constitutes 30 credits.
Firstly, I would like to thank my supervisor at KTH, Mauro Onori who provided valuable feedback. Secondly, I would like to thank my supervisor at Company Y and everyone involved at Company Y who contributed with engagement, support and valuable opinions.
I would also like to thank Mikaela von Yxkull and David Norman for the support during my work.
______Stockholm, June 2018 Filippa von Yxkull
VII
1. Introduction
In this chapter, the background, the problem definition, purpose and research question, study’s expected contribution and the disposition will be presented. Finally, the delimitations of the thesis will be presented.
1.1 Background
Globalisation has over the past 20 years changed the face of manufacturing. Low-cost countries like China were used as offshoring opportunities to lower operational costs and cut supply chain costs. However, with today’s rising labour costs as well as the availability of more efficient automation system, offshoring might come to an end (Manenti, 2014).
In addition to this, there has also been a change in the way consumers purchase their goods, as they hold information about both prices and market trends. Consumers are becoming more impatient and reluctant to long lead-times, demanding highly customized products at a low cost. There is therefore a need for companies to be able to respond quickly to changes in demand and get closer to their customers (Manenti, 2014).
The world’s largest growth trend in the robotics industry happens in Asia with China as the market leader (IFR International Federation of Robotics, 2017). This is due to countries like China are experiencing labour shortage and pressure from low labour countries in Southeast Asia, such as Vietnam, which have resulted in China putting more emphasis on automation.
European companies are struggling to keep up and be competitive to gain market share from countries like China (Onori, Sandin and Alsterman, 2012). In addition to this, there is a rapid decline in the workforce in Europe. To be able to strengthen the competitiveness and address these issues companies need to automate their production (Onori and Oliveria, n.d.) If specific conditions are met, the robot system market is expected to rise in Europe (Onori, Sandin and Alsterman, 2012)
However, to be able to automate the production the products and components need to be designed for automation (Eskilander, 2001), since many of the issues experienced in automating the production system stem from the fact that the products are designed for the traditional manufacturing and assembly processes (Scarr and McKeown, 1986). According to Sanders et al. (2009) the most important process in manufacturing is the assembly process. Despite this, the automation of the assembly process has failed to succeed, since the same basic tools are used, as at the time of the Industrial Revolution (Boothroyd, 2011).
1 DFA (Design for Assembly) is a methodology that has been used since the 1980s. The method aims to simplify the product structure and reduce the assembly cost (Boothoyd1992). DFAA (Design for Automatic Assembly) is based on DFA, however only focusing on automatic assembly, since working with DFA for manual assembly does not correspond to the product being suited for automatic assembly. Designing a product for automatic assembly allows maximum flexibility as the product can be assembled both manually and automatically (Eskilander, 2001).
1.2 Problem Formulation
Despite the many reasons to invest in automatic assembly solutions, designing for automatic assembly has not received highest priority of the design department at manufacturing companies and it is still common that products are assembled manually (Eskilander 2001).
One manufacturing company that is recognising the benefits of automating the assembly process is Company Y. With volumes expected to increase there is a need to increase the output from the assembly shop, with human assembly workers limited to work a few hours per day. In addition to this, the management of Company Y has set a requirement of 90% automation level on the new designed products introduced in production.
Despite this, Company Y is lacking a structured way of making their products more suited for automatic assembly. Currently, the work of creating a competitive product is predetermined by the work of the designer. There is therefore a need to implement a structured method to make the products more suitable for automatic assembly to increase the application of automation in production. Design For Automatic Assembly (DFAA1) is a systematic approach to determine how well a product/module is designed for automatic assembly.
1.3 Purpose & Research Question
The purpose of this master thesis is to investigate how Company Y should implement DFAA. This to make the products and components more suitable for automatic assembly and increase the application of automation in production. Based on the purpose, a main research question has been formulated:
v How should Company Y implement DFAA, to increase the possibility to automate the assembly process?
To be able to answer the main research question three sub-questions have been formulated.
Ø How could a structured DFAA method be applied?
1 This thesis uses the definition of “DFAA” as subdivision of “DFA”, were the term DFA is used in a more comprehensive way.
2 Ø Where in the development process should the early adaption of DFAA be implemented?
Ø Which departments should be involved and what competence is need?
Ø What should the decision model look like?
1.4 Delimitations
The study is delimited to only analyse two DFA methods. However, only one method was chosen to be analysed in practice namely, i.e. the DFA2-method created by Eskilander (2001) and provided by the Company Solme as a software solution. The other DFA method- DFMA by Boothroyd and Dewhurst (2011) was only treated in the literature study.
Furthermore, two designs were chosen to be evaluated using the DFA2-method, the current design subassembly of a mechanical component and a new developed concept of the mechanical component. The DFA method includes a cost analysis that reveals the costs related to the design concepts. However, this thesis will not include any in-depth financial aspects or cost aspects. It is evident that the financial aspects linked to the work of DFAA will affect the decisions making and the overall business model at an organisation. This should be viewed separately.
The study includes an investigation on how other companies have implemented and applied DFA. The investigation is delimited to analysing three manufacturing companies that successfully have implemented DFA, namely Ericsson, Scania and Company X.
1.5 Study’s Expected Contribution
The Expected contribution of the study is on an academic level and a managerial level.
Academic Level: On an academic level this study aims to contribute in the area of DFA. Several researchers have highlighted the need to work with DFAA in order automate the assembly system, as well as the benefits when implemented (eg. Boothroyd, Dewhurst and Knight, 2011; Eskilander 2001). However, little information could be found on how it should be implemented and the workflow of the methodology. This study aims to contribute with this knowledge.
Managerial Level: Managerial level corresponds to what the findings of the study entails for the companies (Blomkvist and Hallin, 2015). A lot of aspects must be considered when implementing a new methodology for product design in a company. From a managerial perspective, the study aims to contribute to the valuable information of how an early implementation of a DFAA-method should be addressed as well as its application.
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1.6 Disposition
The disposition of the thesis is illustrated in figure 1 below. This to enable the reader to easily develop an understanding of the structure of the thesis. Figure 1 gives an overview of the eight chapters with the related sub-sections.
Figure 1 illustration of the structure of the master thesis
4 2. Literature & Theory
In this chapter, the literature and theoretical studies connected to DFA will be presented. First, definitions of important terms and concepts will be given.
2.1 Definitions
The thesis aims to investigate an early implementation of DFAA and how it should be applied. The theory of DFA has been considerably investigated by Boothroyd (1992). Despite the literature being written over twenty years ago, it is still relevant and based on current research about DFA. According to Moultrie and Maier (2014) the field of DFA is relatively small and the absence of academic papers suggest that new information will be difficult to discover. Many principles used in engineering design textbooks were established in the 1960s and the 1970s.
The work of DFAA has been extensively investigated by Eskilander (2001) and is therefore referred to throughout the entire thesis. The DFAA method that was applied in this master thesis is based on Eskilander’s DFA2-method. To understand the literature, the definitions of the main concepts will be described, i.e. assembly, concurrent engineering, DFX, DFA and DFAA.
2.1.1 Assembly
Assembly is a part of the production system. According to Nof, Wilhelm and Warnecke (1997) the assembly process is defined as:
“The aggregation of all processes by which various parts and subassemblies are built together to form a complete, geometrically designed assembly or product (such as a machine or an electronic circuit) either by an individual, batch or a continuous process” (Nof, Wilhelm and Warnecke, 1997, 2).
According to Sanders (2009) the assembly process has an impact on the products lead-time, quality and cost and is therefore considered to be the most vital processes. The assembly process reports for 40% of the manufacturing cost. In addition to this, beyond 70% of the manufacturing costs is set in early conceptual design phases. Assembly should therefore be considered early in the design cycle (Sanders, 2009)
There are three methods of assembly: manual assembly, high-speed automatic assembly and robot assembly. The assembly methods can be applied individually or more commonly be used in a combination. Before selecting the appropriate assembly method, the design of the products needs to be analysed (Kalpakjian and Schmid, 2009).
5 2.1.2 Concurrent engineering
Concurrent engineering is defined as an approach of working in multi-disciplinary teams as well as working parallel. By doing so, every phase of the product life cycle is co in every stage of the product development (Eskilander 2001). This is to avoid the mistakes associated with the traditional sequential product development, where the different departments are maintained separately (Filippi and Cristofolini, 2010). The traditional serial development can be compared to the “over the wall” approach (see figure 2), where the design is thrown over an imaginary wall to the manufacturing department to handle the issues that occur in production (Boothroyd, Dewhurst and Knight, 2011).
Figure 2 Illustration from (Boothroyd, Dewhurst and Knight, 2011) displaying the "over the Wall" approach.
According to Eskilander (2001) there are two main advantages by working with concurrent engineering. Firstly, problems that would have been discovered later in the development chain, can be identified early. Secondly, if the work is done parallel the total lead-time can be shortened. In addition to this, by working in parallel, feedback from the manufacturing department can be included in the design of the product, which can result in an improved product. However, there is a need for tools to enable visualisation of the relationship between the parameters of design and manufacturing. According Li and Hwang (1992) DFA is a valuable tool for achieving concurrent engineering.
2.1.3 DFX
DFX is an acronym for the term “Design for X” and refers to the methods that are focused on specific aspects of the product life cycle (Filippi and Cristofolini, 2010). The X could be categorized into two interpretations, namely a phase of the life cycle of the product (assembly, manufacturing, or service) or a property (cost, environmental aspects or quality) (Eskilander, 2001). The different sub-divisions of DFX are illustrated in figure 3, where DFA and DFAA will be described further in the sections below.
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Figure 3 Illustration from (Eskilander, 2001) displaying the hierarchical structure of DFX.
2.1.4 DFA
Design for Assembly (DFA) was established in the 1980s and is as relevant today as when it was first recognised. DFA is a process for improving a product design for an easy and cost- effective assembly (Moultrie and Maier, 2014).
There are several benefits of working with DFA and Egan (1997) categorises the potential effects into short-term and long-term. The short-term effects of implementing DFA correspond to the number of reduced parts, reduced assembly time and reduced manufacturing and assembly costs. The long-term effects of implementing DFA correspond to improved quality and that conditions for concurrent engineering are facilitated.
According to Moultrie and Maier (2014) there are two ways DFA can be considered i.e. general DFA heuristics and systematic methods for analysing assemblies. General DFA heuristics correspond to the images which display “good assembly practices” (e.g. all assembly should be done from above) versus “poor assembly practices” (e.g. assembly is done from several directions). The heuristic images are easy to understand, though are difficult to use in a structured fashion, for example in a design review context. Systematic methods for analysing assemblies correspond to the methods that enable designers to identify and improve the design in a structured way (Moultrie and Maier, 2014)
2.1.5 DFAA
Design for Automatic Assembly (DFAA) is based on DFA (see figure 3 above), however only focuses on automatic assembly. Boothroyd and Dewhurst (2011) discuss robot assembly, which is included in automatic assembly. Automatic assembly is defined as any mechanical assembly process that has no human interaction. The issues are similar if the assembly process is flexible automated or hard automated (Eskilander, 2001).
2.1.6 DFA guidelines for automatic and robot assembly
There are several general design guidelines that can be applied by a designer when developing the design. The design guidelines are a set of design rules that aim to consolidate the manufacturing knowledge. Boothroyd Dewhurst and Knight (2011) present several guidelines
7 for manual assembly, machining, high-speed automatic assembly and robot assembly etc. However, in this section only the guidelines for automatic and robot assembly will be described.
The problem when automating the assembly process, is to automatically handle the part, rather than inserting operation. Therefore, when considering design for automation the design emphasises on ease for automatic feeding and orienting (Boothroyd, 1992). The design rules for high speed automatic assembly are categorised into rules for the product design and design rules for the parts. These are summarised by Boothroyd, Dewhurst and knight (2011) as follows:
Product design rules 1. Reduce the number of parts. 2. Establish a base, where the assembly is built. 3. Establish features on the base part that enable the part to have a stable position in the horizontal plane. 4. Establish a design where the product can be built up in layers. The parts should be assembled from above and positively located, i.e. no indication to move during the action of horizontal forces. 5. Design parts with chamfers or tapers. This will guide and position the parts correctly. 6. Avoid fastening operations (e.g. screw fastening), since they are both time consuming and expensive.
Design of a Part rules 1. When parts are placed in bulk, they can tangle with similar parts. Try to avoid holes or slots and projections. This can also be done by making the slots smaller than the projections. 2. Establish symmetry in parts so no orienting devices are needed. 3. When symmetry cannot be established the asymmetrical features should be exaggerated. This is to facilitate orienting.
The design guidelines for robot assembly are similar for those of high-speed automatic assembly and manual assembly. The design rules for robot assembly are summarized by Boothroyd, Dewhurst and Knight, (2011):
1. Minimize the part count. 2. To make the parts self-aligning, use features such as leads, chamfers, lips etc. This is of importance, to ensure consistent and fault-free in part insertions. 3. Parts that are not secured immediately after insertion should be self-locating. This is of importance since a single robot arm cannot hold down unsecured arms and special fixturing is needed. 4. All parts should be designed so they all can be used by the same robot gripper for insertion and for gripping. 5. Establish a design where the assembly is done directly from above in a in a layer fashion.
8 6. The need to manipulate a previously assembled part or reorienting partial assembly should be avoided. 7. Parts should be designed so they can be simply handled from a bulk. This is to avoid that the parts to nests or tangle when stored in bulk. Part that should be avoided include, flexible parts, abrasive parts (since they will wear the handling systems), sticky or magnetic parts etc. 8. When parts need to be presented by automatic feeders, make certain that they can be oriented using simple tooling. 9. When parts that needs to be presented by automatic feeders, make certain that they are presented in an orientation, which they can be gripped and inserted without manipulation. 10. Ensure stable resting if parts need to be presented in magazines or part trays, so they can be gripped and inserted without manipulation.
2.2 DFA methods
There are several methods that are used to support product design. The twelve commercially available DFA methods are listed in figure 4 (Eskilander 2001).
Figure 4 Table of the most common commercial DFA methods (Eskilander, 2001)
In this section, two DFA methods are going to be presented, namely the DFMA methodology created by Boothroyd and Dewhurst and the DFA2-methodology created by Eskilander. DFMA is investigated since it is one of the most widely recognized DFA methods (Stone, McAdams and Kayyalethekkel, 2004). The DFA2-method is investigated since it has a clear focus on automatic assembly (Eskilander 2001).
9 2.2.1 Boothroyd’s & Dewhurst’s DFMA Method
Boothroyd and Dewhurst are pioneers in the field of design for manufacture and assembly and created the methodology DFMA. The term “DFMA” is a combination of the terms DFM (Design For Manufacture) and DFA (Design For Assembly). The purpose of the methodology is to reduce the number of assembly operations by reducing the number of parts and to make the assembly operations easier to perform. There are four methods for DFA available from Boothroyd and Dewhurst Incorporated, namely methods for manual, robotic, automatic and printed circuit boards. However, the most commonly used DFA method is for manual assembly (Boothroyd, Dewhurst and Knight, 2011).
A central role of DFA-methodology is to reduce the part count, since the spate part reduction decreases the cost of assembly and the total cost of parts. According to Boothroyd, and Knight, (2011) to determine if the part needs integration, three question should be asked:
1. Does the part move in relation to already assembled parts, during assembly of the product? 2. Should it be of a different material or can it be isolated from parts already assembled? 3. Must the part be separate from already assembled parts, otherwise assembly or disassembly would be impossible?
If any of the three questions are answered with “yes”, the part/component is validated for its existence and needs assembling. If all the three questions are answered with “no” the part is a candidate for integration (Boothroyd, Dewhurst and Knight, 2011).
The manual DFA-analysis is based on estimated assembly times for handling, insertion and fastening of parts. To estimate the manual assembly times a classification and coding system is used, where factors affecting the handling time and insertion time are taken into consideration. Examples of part features affecting the handling time are the part symmetry, thickness, size, weight and if a part requires two hands for manipulation. Features that influence the time to insert and fasten a part is if it is designed to avoid jamming, its part geometry, if it has obstructed access and if there is restricted vision (Boothroyd, Dewhurst and Knight, 2011) A design that does not correspond to the ideal design is punished with a longer assembly time, as it takes longer to e.g. orient (Eskilander, 2001).
DFA-index
The DFA-index or assembly efficiency is used to measure the proposed design. Furthermore, it is used to compare different designs (Li and Hwang, 1992). There are two aspects that influence the assembly cost, i.e. the ease for handling, insertion and fastening of parts and the quantity of parts in the product. The DFA index is illustrated in formula 1 below:
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Formel 1: Assembly efficiency formula (Boothroyd and Dewhurst (2011)
Ema is defined as the assembly index or assembly efficiency. Nmin is corresponds to the minimum hypothetical number of parts. The sum theoretical minimum of parts corresponds to the ideal number of parts in a product, i.e. possible integration of parts according to the three questions stated in the text above. ta refers to f the basic assembly time for one part. Finally, tma refers to the sum of total estimated assembly time, i.e. the time it takes to assemble the product, when the part presents no assembly difficulties (Boothroyd, Dewhurst and Knight, 2011).
High speed assembly and robot assembly
As aforementioned, it is possible to analyse the products and component for ease for automatic assembly, i.e. high-speed assembly or robotic assembly. The difference between the two types of assemblies is that high-speed assembly requires less flexibility as well as a lower equipment cost (Eskilander, 2001).
The analysis for automatic assembly resembles the analysis for manual assembly except that the analysis estimates cost for orientation and handling instead of estimated assembly times. The result of the evaluation is an average cycle time (Boothroyd, Dewhurst and Knight, 2011).
Software solution DFMA Inc.
The methodology DFMA is both available as a handbook and as a software solution. The software solution utilizes a question-and-answer interface (dfma.com, n.d.). The software interface is illustrated in figure 5.
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Figure 5 Illustration of DFMA Software, DFA product Simplification (dfma.com, n.d.).
2.2.2 DFA2, Design For Automatic Assembly method
DFA2 is a method within the domain of DFAA. The DFA2 method can be applied in early developments of products, since it does not require a prototype. The main objective with the method is to achieve a design that is as non-complex as possible, which yields the simplest assembly process. However, the functional requirements still should be fulfilled (Eskilander, 2001)
Design rules
DFA2 consists of several structured design rules or guidelines. The purpose with the design rules is to provide the user with information to design the product in respect to automatic assembly. This enables the user to focus on one assembly problem at a time as well as ensure that no information is overlooked (Eskilander, 2001).
The design rules are divided into two sections, namely product level and part level. Product level has design rules or questions that corresponds to the entire product/modules. The Part level have design rules or questions that correspond to each part in the product/module (Eskilander 2001)
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Figure 6 Guidelines for product level and part level (Eskilander, 2001)
Criteria
The method also includes a qualitative evaluation criteria. The evaluation criteria are based on a levelled points scheme, where:
• 9 points are rewarded if it is the best solution from an automatic assembly perspective • 3 points are rewarded if it is an acceptable solution. However, the solution is not completely satisfactory from an automatic assembly perspective. • 1 point is rewarded if the solution is unwanted from an automatic assembly perspective.
The possible hazards of choosing a solution that is not perfect in respect to automatic assembly is visualized using the levelled point scheme, with the three levels 9,3 and 1 (Eskilander 2001).
At the end of the evaluation the points rewarded to the product/components are summarized. The total score for the evaluated product is divided by the maximum ideal score and multiplied by a factor of 100, which is illustrated in the formula 2. Hence, the DFA2-index tells the user how close the product is to an ideal solution (Eskilander 2001).
Formel 2 Calculation of the DFA2 index
13 In addition to this, the DFA2-method supports a cost analysis, which is based on an activity analysis (Eskilander 2001).
Software solution AviX DFX-Module
AviX is mainly a video analysis based software created by the company Solme. AviX enables analysis of the manual assembly processes, by combining video analysis with time and motion studies. Currently the software offers nine modules, AviX Mehod, AviX Balance, AviX Resource Balance, AviX FMEA, AviX Smed, AviX DFX, AviX Ergo, Execution Optimizer and Shop Floor viewer (Avix.eu, n.d.).
DFX is a collective name for the three methodologies, DFS (Design For Service), DFM (Design For Manufacture) and DFA (Design for Assembly), where the DFA method is based on Eskilander’s DFA2-method. AviX DFX offers standard templates, however also provides the possibility to supplement the system by offering the ability to customize the templates. This means that new aspects (also known as guidelines) could be created or updated as well as redundant aspects in the method could be removed.
The main advantages with utilizing a software is that it simplifies the use of the method (Eskilander, 2001). The documentation and the communication of the assembly guidelines is also simplified. The result of the DFA2 method is also made clearer, by the colorization of the score from the evaluation, which is illustrated in the snapshot from the software in figure 7.
Figure 7 Snapshot of the DFX module provided by AviX (AviX.eu, 2018)
14 The software provides visual aids, such as videos and images, which is illustrated in the snapshot in figure 8.
Figure 8 Illustration of the visual aids provided by AviX (AviX.eu, n.d.)
All information and comments during the DFA-analysis could be captured in AviX. This is of importance when issues with the design are recognized. According to Solme (2018) it is advisory to document the cause and what actions that need to be taken. In addition to this, the problem/action could be assigned a priority level from low, high and intermediate.
The result of the DFA-analysis is a DFX report, where all the evaluated parts and subassemblies are displayed (see figure 9). From this, each part and subassembly receives a DFA2-index, which is used to calculate the aggregated DFA2-index for the product/module. In addition to this, an assembly time is estimated for each component as well as an aggregated assembly time for the entire product/module. Finally, there is a possibility to calculate the purchase cost for the product/module.
Figure 9 Result of an DFA2-analyis on part level.
The evaluation can also be done on a product level, where the product/module receives a DFA2- index.
15 Application of DFA2
DFA2 could be used to evaluate an early design development or used to evaluate an already existing product/module. In the early design of a new product/module it is preferable that it is modularised using the MFD-method. The analysis should be initiated by the guidelines for the entire product/module. The next step is to evaluate each component, using the guidelines that correspond to the part level (Eskilander, 2001).
When using the method for an already existing product, the first step is to analyse the structure of the object, which determines the assembly sequence. The assembly sequence is initiated with the base object, on which all remaining parts are assembled. The object can be broken down into subassemblies, if the assembly occurs without disruptions. The object is analysed on a product level and then part level (Eskilander 2001).
2.3 Implementation of DFA
There is no “correct approach” of implementing DFA. However, DFA can be facilitated by using a demonstrator, until the DFA tools and techniques become a standard approach when introducing new products (Eskilander, 2001). The following section concludes the important aspects when implementing DFA into the organization.
2.3.1 Company mission, vision and objectives
The company needs a mission to distinguish itself from other companies on the market. The mission incudes the company’s future state- “the vision”. The vision is the intended objectives, that are supposed to serve as a guide for the internal decision making. A well-defined vision can motivate employees. The vison can be broken down into short and long term goals. The goals should be defined as SMART2 (Hallin and Karrbom Gustavsson, 2015).
According to Synnes and Welo (2015) to be able to make successful decisions concerning automation, they should be associated with the organizations long term goals. This since both over-automation and under-automation can have a negative effect of the company’s competitiveness (Synnes and Welo, 2015). Furthermore Frohm (2008) concludes that “The main reason that an automation project ends in failure is unrealistic or undefined objectives” (Frohm, p 65, 2008).
2.3.2 Implementation strategies
According to Bruke and Carlson (1987) the implementation of DFA should be done as following: 1. Accommodate a DFA overview to senior management 2. Select a DFA champion/coordinator
2 SMART (Specific, Measurable, Attainable, Relevant and Time-bounded)
16 3. Define objectives, for example reduce costs. 4. Select a pilot program 5. Select a test case 6. Establish the individual members and the structure of the team. 7. Establish coordination of the training. 8. Initiate the first workshop. 9. Maintain and keep having meetings as needed.
According to Dean and Susman (1989) there are four approaches that can be used for structuring an organisation for “manufactural design” namely:
1. Manufacturing sign-off The manufacturing sign-off refers to the veto power that is given to the manufacturing department over the design department. With other words, the product cannot be released until the manufacturing department gives their permission. The main advantages with this approach is that a product with a low reducibility is unlikely to reach production. The main disadvantage of this approach is that there is no base for creative interchange between the two functions.
2. The integrator The integrator corresponds to the individuals that work with the designers with the producibility problems and operates as liaisons to the manufacturing team. This means that the integrator’s job is to maintain the manufacturing and the design standpoints in balance. In other words, if an integrator supports manufacturing too heavily he/she will lose credibility with the designers and vice versa. A drawback with this approach is that it’s too difficult to find an individual to act as an integrator, since the education for manufacturing and design requires two degree programs. In addition to this, using an integrator can result in the so called “guru syndrome” i.e. if only the integrator works with producibility then no one else will. The organization will become very dependent on one or a few individuals working with ease for assembly. Finally, the approach does not facilitate concurrent engineering.
3. Cross-functional teams Cross-functional teams means that different departments work collaboratively throughout the product development process. At the minimum, this involves individuals from the manufacturing department and from the design department. The main advantage with this approach is that the different functions in the organisation can influence the design before release and that concurrent engineering is facilitated. The disadvantage with this approach is that designers feel prohibited, due to the cross functional team demand of the design becomes too unrealistic and the designer’s creativity become undermined. The approach requires that the individuals that are involved in these cross- functional teams receive broader knowledge within producibility, as there is no longer a single producibility expert.
17 4. The product-process design department The product-process design department corresponds to creating a single department that is responsible for both the product and the process. The greatest structural change is created through this approach, which also can cause the greatest resistance from the employees. However, the approach supports concurrent engineering and there is mutual education through a day-to-day contact. There are a series of variations to this approach namely: • A senior manager that controls both the product and the process, however each function have separate units. • A single department including product and process engineers, with a manager that is responsible for both the two functions. • Individuals that are responsible for both functions, i.e. product-process engineers, which are composed into one department.
According to Ahm and Fabricious (1990) it is important that the management is involved and understand the practises of a DFM/DFA project, i.e. that it requires more resources to be assigned in the beginning of the developing phase.
2.3.3 Implications of implementing DFA
The implementation of DFA is prone to be more successful, if there are extensive databases available and cross-functional communication skills already set in the organization. The databases with information of manufacturing and design can be “bought” from consultant firms. However, the organizational structures needed to facilitate cross functional communication skills cannot be “bought”. Boothroyd, Dewhurst and Knight (2011) state several falsely claimed reasons for not implementing the DFA. Four of them are described below:
Not enough time This reason corresponds to the designers experiencing that they do not have sufficient time to do their work, as they feel the need to decrease the time from design to the manufacture stage. DFA should be considered in all stages of the design process, however specifically in the early design stages. This is due to the large amount of design changes that occur in the conventional design process, when the drawings of the design are passed to the manufacturing department, whose job is trying to optimize the process and produce the final project. The later these design changes occur the costlier they become and they often lead to a delay in the product release. Thus, by implementing a DFA method, more time is spent earlier in the design phase, which is compensated as time savings can be reaped when prototyping takes place. This is illustrated in figure 10.
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Figure 10 Illustration of time savings achieved by implementing DFMA (Boothroyd, Dewhurst and Knight, 2011).
Not invented here Difficulties can be experienced when new methods or techniques are suggested to designers. Especially when the decision of implementing DFA comes from the top management, who has the wish to reap the success resulting from DFA. This can result in resistance from the designers.
Ugly baby syndrome Conducting a DFA-analysis often involves an outside group analysing a design, trying to find improvements to make the design more suited for assembly. However, this can create great resistance from the designer, as telling a designer their design needs improvement can be compared to telling a mother her baby is ugly.
We have been doing it for years “We have been doing it for years” relates to the fact that a company already uses a producibility procedure to make parts more suitable to manufacture. However, these are often done in the end of the design process where the vital decisions which affect the manufacturing costs already have been made.
2.4 Impact DFA has on the future of manufacturing
According to Onori (2002) product design can be seen as an integral step in assembly system development. To raise the potential of automation, DFA plays a central role. DFA decreases the obstacles such as assembly complexity and incompatibility and industrial robots will be easier to integrate. In this section, the impact DFA has of the future of manufacturing will be described.
2.4.1 Modularity in respect to DFA
Modularisation enables a step by step development of the manufacturing system. As illustrated in figure 11, different parts of the assembly system can be manual respectively automatic. According to Ericsson and Erixon (1999) products can be modularised and each module can be
19 allocated to a specific assembly system. This enables small factories within the factory to be built. Parts of the product assortment can therefore be automated (Ericsson and Erixon, 1999). As pointed out by Eskilander (2001), if module area two assembles a module that is applied in numerous products through the product assortment, a flexible assembly system might be economically feasible. This is because the cost is shared among many module variants (Eskilander, 2001). However, with an automatic assembly system in the area (factory) the products need to be suited for automatic assembly, i.e. suited for the assembly process.
Figure 11 Factories within the factory (Ericsson and Erixon, 1999)
According to Eskilander (2018) modularity facilitates the work of DFA and DFAA. Applying DFA on single products is not sufficient as it only leads to a specific module variant being optimal, whilst the other module variants within the product assortment being overlooked. This can lead to the risk of sub-optimization, if the product architecture has not been defined beforehand (Ericsson and Erixon, 1999).
Through modularization, the number of product variants can be controlled. The same modules and components can be applied in more than of product family. This enables the possibility to have different product families with the same base materials or operation sequences, which can be used when designing a new product or production system (Eskilander, 2001). With other words, modularisation contributes to a high configurability and lowers the part count. According to von Yxkull (2018) this makes the work of DFAA become more efficient and not as cumbersome.
A modular method that includes DFA is the Modular Function Deployment method (MFD). The method consists of five steps and is used to define modules i.e.:
1. Initiate with defining the customer requirements for the product, with the help of a QFD (Quality Function Deployment) tool. 2. Choose the technical functions based on the customer requirements. 3. Based on the technical functions identify possible modules with the help of a MIM (Modular Indication Matrix)
20 4. Evaluate the concepts 5. Improve the modules by applying DFA.
2.4.2 Evolvable assembly systems
To maintain a competitive assembly system there are two conditions that need to be met. Firstly, the assembly system needs to be able to respond quickly to the changing conditions. Secondly, the assembly activities need to be performed in an efficient way. The former, could be measured as the time it takes to reconfigure the system, to able to deal with a new product situation. The latter, could be measured as the function of the optimal assembly sequence. For an assembly system to remain ideal for the next production scenario, the system must be re-configured and re-planned. This is both time consuming and costly, as it requires the production to stop. Due to the frequent changes of customer needs, it is seldom successful to run the production to be ideal. With other words, there is a trade-off between production optimality and system responsiveness and it needs to be balance between process optimality and the ability to adapt to new requirements (Akillioglu, Neves and Onori, 2010).
Evolvable Assembly Systems (EAS) is a next generation assembly system that focuses on both agility and mass customization. EAS is based on reconfigurable modular concepts that allow continuous system evolution (Akillioglu, Neves and Onori, 2010).
21 3. Method
In this chapter, the methodology of the study will be discussed. This includes describing the research design & process, the primary sources, the secondary sources and the quality of the analysis. Finally, the ethics taken into consideration while conducting the thesis will be presented.
3.1 Research Design & process
The study was conducted at Company Y, with the purpose to investigate the conditions to implement DFAA into the organization. The master thesis was limited to 20 weeks and in the initial phase of the thesis, considerable amount of time was spent at Company Y (see Gantt- chart in appendix B). This has led to a good understanding of how Company Y currently works with making their product more suitable for automatic assembly. However, most empirics were gathered from the benchmarked companies Ericsson, Company X and Scania. The method is defined as a qualitative method with qualitative interviews and observations.
The thesis initiated with formulating a non-trivial research problem. Based on the problematization, a purpose and research questions could be formulated. The purpose of the thesis is classified as an exploratory research, since the aim of the study is to investigate patterns rather than to test a hypothesis (Collis and Hussey, 2014). In addition to this, the study has not previously been explored to any greater extent (Blomkvist and Hallin, 2015). An inductive approach was selected, where the problematization, purpose and research questions were continuously reviewed (Blomkvist and Hallin, 2015)
The research process was initiated with a pre-study to formulate the problem definition, followed by a literature review. After this the empirics of the study were gathered, which consisted of interviews, observations and an early implementation of DFA2 (workshops). In the analysis, the literature study and the empirical study were linked to be able to draw the conclusions. The research process is illustrated in figure 12.
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Figure 12 displays the study’s research process
3.2 Primary Sources
The primary sources used in this thesis are, interviews, observations, an early implementation of the DFA2-method in the form of workshops and written materials published by Company Y.
3.2.1 Pre-study
In the beginning of the study a research proposal was offered by the author to Company Y. Thereafter, an informal meeting was held to discuss the problem formulation and a supervisor was assigned. However, only a brief problem explanation was given and an extensive pre-study was conducted. Therefore, initial interviews were conducted both to explore the problem and formulate a current state-analysis. In addition to this a literature review was conducted to define the scope and focus of the thesis.
3.2.2 Interviews
The interviews that were conducted during the thesis were of a semi-structured fashion, meaning that the pre-determined questions were created in advance, see interview guide in appendix A. During the interviews the questions were asked in a vis-á-vis approach, to support flexibility (Blomkvist and Hallin, 2015).
The interviews were conducted to formulate the research questions and to establish current- state analysis, i.e. to address Company Y’s current conditions to implement DFA. Finally, the interviews were used to conduct a benchmarking. According to Rostek (2015) the purpose of benchmarking is to identify the firm’s superior standards of products, services or processes and to be able to compare the organization’s best practises. Three manufacturing companies were benchmarked in the thesis, namely Ericsson, Company X and Scania. All three companies have successfully implemented DFA into their organization and were therefore of interest. The reasons for the selection of the companies are further described in chapter 4. The informants of the companies were interviewed several times and the interviews were transcribed and sent via
23 email. This was done to avoid misinterpretations of what had been said and for the interviewee to approve the information, so that the confidentiality agreements were kept.
The interviews made at Company Y were conducted to formulate the purpose and the current state analysis. The interviewees were represented from different departments. This was done, to receive different perspectives on the issues that were investigated. This is of importance according to Elisenhardt & Grabner (2007) to avoid the findings being subjective.
The interviews at Company Y was conducted with one interviewee at a time. This was done to avoid the answers being affected by another interviewee (Collis & Hussey, 2014). The interviews were recorded with permission of the interviewee, so the information could be transcribed. In parallel to the recordings, notes were taken throughout the interviews. This was done to be able to follow up on what the informant said during the interview (Blomkvist and Hallin, 2015). All the interviews, meetings and other activities conducted in this thesis are presented in table 1 below.
Table 1 Record of all the interviews, meetings and other activities held during the thesis.
Interviews Title Date Place Description Duration 24 January Semi-structured Design engineer Company Y 50 min 2018 interview Automation 25 January Semi-structured Company Y 1h 10 min Consultant 2018 interview
Global 31 January Semi-structured Production Company Y 50 min 2018 interview Engineering Manager
31 January Semi-structured Project leader Company Y 50 min 2018 interview
Production technician 12 February Semi-structured Company Y 40 min manager 2018 interview
PhD-Stephan 2 February Semi-structured Teleconference 1 h Eskilander 2018 interview 18 April Modular Un-structured Alex von Yxkull 1 h 40 min 2018 Management interview Benchmarking
Producibility engineer 31 January Semi-structured Teleconference 1 h at Ericsson 2018 interview
24 Producibility engineer 15 March Semi-structured at Ericsson Teleconference 50 min 2018 interview
21 March Scania Semi-structured 2 h Global production 2018 Södertälje interview engineers at Scania Semi-structured 4 May 2018 Teleconference 45 min interview New Product 2 February Semi-structured Teleconference 1h 20 min Industrialisation 2018 interview engineer at Company 13 March Semi-structured Teleconference 45 min X 2018 interview Meetings & Other Activities
Initiation of 25 January R&D Company Y Master thesis 1 h 2018 meeting 25 January Company Y Explanation of 1 h Manager R&D 2018 Company Y’s Processes 23 April Company Y PD-process 30 min 2018 Solme DFA2 5 April 2018 Company Y DFA2 review 1 h presentation 9 March Automation R&D and production Company Y 3 h 2018 workshop R&D, production and 25 April Automation Company Y 3 h purchasing 2018 workshops Learning to Solme 2 February Teleconference operate AviX 45 min 2018 DFX module
3.2.3 Observations
The observations made during the thesis were made to be able to formulate the current-state analysis. Therefore, design reviews and automation workshops were attended where the author acted as an “participating observant”, i.e. interacting and asking questions to the person that was observed. The observation methodology was applied since the questions asked were of exploratory nature (Blomkvist and Hallin, 2015).
3.2.4 Early implementation of DFA2
Five 3,5 hours’ workshops were conducted at Company Y, with the purpose to evaluate how a structured method should be applied. The workshops also served as an early implementation of
25 the software based DFA2-method. The workshops were conducted with individuals from different functions in the organizations, i.e. the service department, the production department and the design department. The designs to be analysed were selected by the assigned supervisor at Company Y. The designs that were analysed included the current design of a mechanical component and a new developed design concept. The new developed design was based on the current design.
Before the initial workshop was conducted, the current assembly process of the mechanical component was analysed in production. The BOM-list was added manually into AviX and CAD-files of the subassembly were displayed. In addition to this, a short introduction to DFA was presented. This included explanation of what DFA is, the purpose of DFA, advantages of DFA and a review of the methodology DFA2, where a bicycle bell was examined.
At the workshops, both the current design of the mechanical component and a new developed design concept was evaluated using the DFA2-method. During the workshops, the author acted as a moderator and explained and interpreted the guidelines offered by the software AviX (DFX-module). Notes were taken during the workshop. After the initial workshop was concluded, a short survey was sent out via email, with questions corresponding to how the method was experienced.
The choice of the DFA2-method provided by AviX, was based on observations and interviews made in the pre-study at Company Y. The DFA2 method is a well-established method and over 18 companies participated in the development of the method (Eskilander 2011). The method provides Company Y with a structured way of making their products more suited for automatic assembly. The software AviX is already used in preparation at Company Y. This meant that the information gathered in preparation could be linked to together. All data can be collected at the same place, which avoids the risk of data becoming obsolete.
3.3 Secondary Sources
The secondary sources in this thesis were mainly based on a comprehensive literature study. The literature study was used in the pre-study to identify what other researchers have contributed with in the field of DFA. The literature study was made in accordance with Blomkvist and Hallin, (2015), as it was read broadly in the initial phase, to later be narrowed down after relevant search areas had been identified. The literature study was worked on continuously throughout the thesis and followed the framework recommended by Collis and Hussey (2014), which is illustrated in figure 13.
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Figure 13 Illustration of the flow chart of the literature search (Collin and Hussey, s. 82, 2014)
The literature mainly includes books, journals (both digital and paper), conference papers as well as student projects. The search engines utilised in this thesis was KTHB Primo through the KTH library and Google’s search engine for scientific articles, Google Scholar. The key words used to find the relevant literatures were, DFAA, DFA2, DFA, Design for automation, Product Design, DFX, Modularization.
In addition to this, several documents published by Company Y were provided. The document included information that was used for the current state analysis.
3.4 Quality of Analysis
The quality of the scientific work was closely linked to the reliability and validity of the analysis. Therefore, the two characteristics needed to be scrutinised to be able to ensure the quality of the study.
3.4.1 Reliability
The reliability of the thesis corresponds to the precision and accuracy of the measurement (Collins and Hussey, 2014) or as (Blomkvist and Hallin, 2015) concludes it, studying the right thing. Furthermore, reliability refers to the repeatability of the study, answering the question- if the study was to be repeated a second time, would it produce the same result?
The interviews conducted at Company Y were of a semi-structured nature to facilitate the reliability of the study, see appendix A. However, it is not possible to replicate the same answers since, discussions sometimes deviated from the original topic. However, several interviews and meetings conducted during the thesis can be defined as “unstructured interviews”, i.e. it was
27 not decided in advance what was going to be discussed (Blomkvist and Hallin, 2015). These types of interviews experienced lower reliability than the semi-structured interviews.
The observations conducted and workshops conducted at Company Y have been done in close collaboration with the employees. This improved the outcome of the thesis, however the reliability of the study became lower. This is since it was difficult to replicate the informal conversations. In addition to this, the learnings of the topic DFAA have increased among the participants since the initial workshop, which could affect the result of the workshops conducted at Company Y.
3.4.2 Validity
The validity of the research corresponds to the degree to which a test measures what the researcher intends it to measure and if the result relates to the phenomena under the study (Collins and Hussey, 2014) or measuring the right thing, to put it simply (Blomkvist and Hallin, 2015).
The study was mainly based on interviews and observations. Using semi-structured interviews increased the validity of study, since the interview’s guides ensured that the “right thing” was being studied.
Three companies were benchmarked, to gain different perspectives of how other companies work with DFA. All three companies have successfully implemented DFA, and were therefore of interest. Each interviewee was considered knowledgeable, since they obtained managerial roles within the field of DFA. The interviewees are therefore argued to be valid.
The literature and theory used achieve validity according to Blomkvist and Hallin, (2015), i.e. was presented in the theory and then used in the analysis. This was done to correspond to the purpose and research questions. During the literature research the author has had a critical view of the information gathered. Most of the literature used was published for more than 15 years ago, however is still referred to in present literature and is therefore considered to be valid.
3.5 Ethical considerations
The ethical considerations taken during the study were based on what is written in the Swedish Research Council’s paper. The paper describes four principles requirements of ethnics that need to be met, i.e. the information requirement, the consent requirement, the confidentiality requirement and the good use requirement (Blomkvist and Hallin, 2015).
The first requirement (information requirement) requires that the people that are involved in the study are informed of the purpose of the study. All the interviewees and people being observed in the thesis have been informed beforehand of the purpose of the study via email. Each
28 interviewee accepted to be interviewed, which entails the second requirement (the consent requirement).
All information given by the companies studied have been treated with confidentiality, and have not been shared, which agrees to the third requirement (the confidentiality requirement). Finally, the material that has been collected is only used for the purpose that the author has stated when gathering the material, which relates to the fourth requirement (good use requirement).
29 4. Benchmarking
In this chapter, Ericsson’s, Scania’s and Company X’s way of working with DFA is going to be described. This includes reasons for working with DFA, choice of method and departments working with DFA.
Three manufacturing companies have been chosen for the Benchmark-analysis namely, Ericsson, Company X and Scania. The benchmark was conducted by interviewing industry experts in the field of DFA. The purpose of the benchmarking was to identify best practices and investigate how the firms have implemented and applied DFA.
The choice of the firms to benchmark was based on three main reasons. Firstly, the companies are in the manufacturing business, are of approximately the same size and have similar processes. Secondly, the companies have successfully implemented DFA into their organization and can be viewed as leaders in the area. In addition to this, Ericsson and Company X have implemented the DFA2-metholody provided by AviX, a DFA-method that has been studied in this thesis. Finally, all three companies have experienced similar problems as Company Y is now facing regarding the implementation of DFA.
4.1 Ericsson
Ericsson is a Swedish telecommunication and networking company. The company is one of the largest manufacturers of equipment for telecommunication. Ericsson offers a portfolio of network services, digital services, managed services and Emerging Business, which is driven by 5G and IoT platforms. The company has in the time of writing 100735 employees (Ericsson.com, 2018).
The information in this section is mainly based on several interviews with Anders Ulin (2018). Ulin (2018) is currently working with making base stations more suitable for assembly at Ericsson - a network of base stations enabling mobile phones and other mobile devices to function, through transmitting radio waves (Ericsson.com, 2018).
4.1.1 Reasons for working with DFA
Ulin (2018) states six reasons for working with DFA, namely:
• To identify and judge potential design improvements • To enable a structured way of working with design reviews • To increase cooperation between design and production • Inform design about production strategies for the products
30 • Receive feedback of previous experience from running production • Identify assembly problems early in design
In addition to this, DFA as a tool enables an objective way to confront R&D regarding weakness with the design, without the designer feeling criticized.
4.1.2 Choice of DFA method
Ericsson is currently working with the software AviX and utilizes the DFX-module provided by the company Solme. The reason for this is that Ericsson has been working with the software for preparation in production and the DFX-module was licenced due to practical reasons. The DFX-module has been customized to suit Ericsson, where several guidelines/aspects have been removed, updated and created. Before Ericsson implemented the AviX-DFX module, they used Boothroyd’s and Dewhurst’s DFMA Inc for manual assembly.
Advantages with using AviX DFX-module
According to Ulin (2018) the advantages with utilizing AviX’s DFX module is that the same tool is used for preparation in production as in the DFA evaluation sessions. Aforementioned, AviX enables visualisation of the production system in form a video clip. These video clips can be displayed during the DFA-analysis, which increases the understanding of how the products/components currently are assembled. This reduces the need for explaining the current assembly process and the reasons why products need to be designed to simplify assembly.
In addition to this, the tool can be customized to the company with questions/guidelines that suit their production and their automation requirements. This in comparison to Boothroyd and Dewhurst DFMA inc, which is more standardised and developed more towards the automobile industry. Finally, as aforementioned, AviX provides an assembly time, which can be transferred into cost of assembly.
Disadvantages with AviX DFX-module
According to Ulin (2018) the main disadvantage with AviX DFX is that the DFA-index is subjective. Depending on how the members in DFA-team argue for their own specific standpoint, the output can vary. Furthermore, the index can be manipulated during DFA- analysis to establish a better relationship with the design department. The DFA-index will thereby score higher than it should if the team was principled.
4.1.3 Departments working with DFA
According to Ulin (2018) the result of the DFA-analysis is reflected on both how the team is formed as well as the spirit of the team. At Ericsson, the DFA-analysis is done in cross- functional teams with mechanical design, production (which includes both industrial engineering and assembly personnel or people with expertise of assembly) and production
31 quality. In addition to this, people from logistics, supplier quality, project management and test development may be included in the analysis.
4.1.4 Workflow- DFA analysis
Ericsson’s DFA-analysis consists of five steps, namely:
• Step 1: Put the structure into the database - Type in or import from PRIM
• Step 2: Put all parameters into the structure - Minimum part, shape, symmetry, insertion, handling - Record ideas!
• Step 3: A first evaluation is available - Assembly times, DFA-index, tables and charts
• Step 4: Time for improvement - Can anything be changed with the parts that have the longest operation times?
• Step 5 Reporting and follow up - Decide on when to have the follow up meeting
Step one corresponds to the pre-work that should be done before the DFA-analysis, to avoid the time-consuming activity of putting data into AviX during the DFA analysis meeting. The data about the product could either be typed in manually or imported from PRIM. PRIM is the central Ericsson product catalogue, where all products that are released with related documents are registered (Crnkovic, Asklund and Dahlqvist, 2003).
Step two corresponds to the activity of performing the evaluation based on the guidelines found in the software, e.g. shape or insertion. Step three corresponds to the result of evaluation, where aggregated DFA2-index and aggregated assembly time is received. Step four is according to Ulin (2018) the most important step. At step four the result of the evaluation is examined and ideas of improvements to lower the longest operation time are discussed by the cross functional DFA team.
At step five, an action list (AP-list) is created, which is illustrated in figure 14. The action list is the outcome of the DFA-analysis and consists of several actions (e.g. issues with the design or possible design solutions) that needs to be further investigated. The actions are assigned to a member of the group together with an open date (when the issue was found) and closing date (when the issue is signed). The action list is used and updated through the entire project. Ericsson grades each action according to three priority levels, namely minor, intermediate or
32 major. Major corresponds to problems that are going to create issues in production. Finally, next the follow-up meeting is decided to revise the action list.
Figure 14 snapshot of action list (Ulin, 2018)
4.1.5 DFA in the development process
Ericsson’s development process, also known as the F-model, consists of seven F-decisions, namely F0, F1, F2, F3, FA, F4 and FG. The decisions are taken in a sequential order according to the model.
According to Ulin (2018), the probability of a successful result is higher when the work of DFA is applied in an early phase of the design. In the early phase, the company avoids the expensive and time-consuming task of making late design changes. The first DFA-analysis should happen before the conceptual design is finished. Table 1 illustrates the different stages in the design process, where DS stands for design status. Table 2 Ericsson’s design process
Design process DS Design object is defined and product number is registered DS1 Start of design work DS1/1 The conceptual design is ready and all docs to physical design are prepared. DS2 Basic design work is completed preliminary document are available DS2/7 Connection between product structure is frozen. DS3 Product function is verified and approved, design is released DS4 All documents (product information) have been reviewed, approved, registered and released and are available for order.
The initial DFA-analysis (i.e. the DFA2-evaluation in Avix) is introduced in the DS1/1 phase, i.e. at the start of the design work (see table 2). Before the DFA-analysis is started it receives
33 input from the DFX-baseline (see figure 15). The DFX baseline contains critical aspects for products within the same product family. The purpose of the DFX baseline is to ensure that new products within a product family do not diverge. Since production areas cannot be dedicated for single products, re-use and modularization of standard processes steps are needed.
Figure 15 DFA in Ericsson’s design process
Once the initial DFA analysis has been performed according to the guidelines in AviX, a DFA- report is created in Excel. The report consists of images and CAD-files of the design. However, this step has been taken away at Ericsson as it is viewed as redundant. Instead the AP-list is created based on the DFA analysis.
The DFA analysis (also known as DFA-review) is then updated into the DS2 phase, where the design work is completed. At this stage, the design is re-evaluated together with the AP-list, in which the action list is updated, where old issues are closed and new issues are opened. The AP list ends up in a DFX-measurement, where the major, intermediate and minor actions are measured. This is further described in the section below.
The number of times the DFA analysis is updated depends on the number of prototypes produced. This means that if two prototypes are created, two DFA reviews need to be performed. This is illustrated in figure 16, where P1 and P2 corresponds to prototype one respectively prototype two. A DFA review needs to be performed before the “creation of drawing for P1”, as the designer needs time to create the drawing and time to order the right material. If the DFA-analysis is done too close to the creation of the prototype, changes of the design become difficult. “Prototype 1 follow up” is the process described earlier, i.e. update of the AP-list. Same process is repeated for the second prototype.
34
Figure 16 DFA in the design process
The final step of the DFA work is to transcribe the AP-list, which is done between the phases DS3 and DS4 (see table 2). This means that all the redundant information in the AP-list is removed. The transcribed (clean) AP-list provides a history of all the issues that were experienced in the project. This is to avoid repeating old mistakes and issues with the product, regarding ease for assembly. Furthermore, based on the AP-list, new guidelines are continuously updated or created in AviX. Since, if the same assembly-related problems keep occurring in next product development project, it is possible that there is a guideline/question missing in AviX, that corresponds to that problem. Ulin (2018) compared this way of working with the practice of Lean.
Aforementioned, Ericsson grades issues/actions in the AP-list according to three priority levels, namely minor, intermediate or major, which are assigned a score of 1, 3 and 5 respectively. The DFA action list is visualized as a graph, which is illustrated in figure 17. This enables the manager to receive an overview of how the project is proceeding. The manager can also control that the design/product is continuously improved by only allowing e.g. 15 majors at a specific stage in the process.
35
Figure 17 Illustration of the AP-list measurement
4.1.6 Implementation
At Ericsson, the most important aspect for implementing DFAA was the acceptance from the management and to have a clear purpose of the methodology.
4.1.7 Decisions model regarding DFA
Ericsson does not have a clear structure of the decision model regarding making their products more suitable for assembly. According to Ulin (2018) the decision taking varies depending on the people involved in the project.
The designer has the responsibility of the design of the product. However, production can inform the control group if they find the design to be insufficient in ease for assembly. The control group then have the responsibility to inform the designer.
4.1.8 DFA initiator
According to Ulin (2018) the main driver of DFA should come from the production department since the constructor/designer already has extensive requirements to take into consideration, e.g. demand to provide cost effective solutions from purchasing, demand to be robust from product owner/customer etc. and the work of DFA might not be prioritized.
Ericsson has employees that are dedicated only to work with DFA and their title is “producibility-engineer”. This person is responsible for all work related to DFA.
36 4.2 Company X
Company X is a medical device company that designs, manufactures and supplies hearing implants.
The information in this section is based on several interviews with Interviewee X (2018). Interviewee X works as an NPI (New Product Industrialisation) engineer at Company X. Interviewee X is also responsible for all DFA-work at Company X, i.e. to make the hearing aids more suitable for automatic assembly.
4.2.1 Reasons for working with DFA
Company X initiated their DFA-work five years ago. The main reason for working with DFA was to increase the quality and to increase its production yield.
After implementing DFA (on the next generation of products) Company X could decrease their time to market with 33%, increased the yield in production with 10-15% and decreased the customer complaints and quality issues considerably.
4.2.2 DFA Method
Company X is currently working with the software AviX provided by Solme and utilizes the DFX-module. Company X also uses AviX for resources balance to create an efficient flow optimization. Company X used to work with Boothroyd and Dewhurst DFMA, however found it too detailed to be handled efficiently.
Company X uses DFX-module for automatic assembly, with the reason “if the product is suited for automatic assembly then it will be easier to assemble manually”. The company has customized the method by removing aspects such as automatic gripping, orientation, centre of gravity, shape and length, joining and assembly motions.
4.2.3 Departments working with DFA
At Company X the DFA-team, that performs the DFA-analysis, consists of production technicians and people from the Design and Development (D&D) department. In addition to this, the purchasing department should be involved more frequently. This is to receive the expertise regarding which manufacturing methods that are available today by the supplier. Furthermore, a representative from the purchasing department is needed to answer the aspect/guideline “Level of Defects” in AviX.
According to Interviewee X (2018) it is essential not to base the DFA-evaluation by anecdotal experiences in production, as the methodology can become subjective. Principal facts and research is of importance. This is since production has the tendency to be too kind in their
37 judgement of the design.
4.2.4 Workflow of DFA analysis
The workflow of the DFA2 analysis at Company X consists of the following steps:
• Step 1 - a BOM is created manually and imported into AviX. A meeting is conducted to go through the BOM and create a manufacturing BOM/MBOM. The components are set into a theoretical assembly order.
• Step 2 - the first DFA-evaluation is conducted. Each component is evaluated according to the questions provided by AviX. Notes/actions are taken at the meeting and a responsible person is assigned to a guideline/aspect when needed. The evaluation takes approximately six hours, in which 20-25 components are evaluated.
• Step 3 - the result of the evaluation is available and the components are ranked according to the lowest DFA-index. Potential design improvements are discussed. The notes/actions that are taken during the meeting are transcribed and e-mailed to the entire team or to specific individuals that participated in the meeting.
• Step 4 - a follow-up meeting is conducted to review the new design proposals and actions. New changes are proposed on the revised components as well as new actions. The follow-up meeting is executed when considerable design changes have been made.
Step one, corresponds to the preparations that need to be done before the DFA2-analysis takes place. A meeting is therefore conducted to go through the MBOM and set the components into a theoretical assembly order.
Step two relates to the DFA2-analysis where each component is evaluated according to the DFA2-aspects. All aspects in AviX, that are rewarded with 1 point, should always be commented. In addition to this, a responsible person is assigned to a specific DFA2-aspect, when needed, with the purpose of investigating it further.
After the evaluation has been completed (step three) the components are prioritised, according to the lowest DFA2-index. Once the components with the lowest DFA2-index have been identified, design proposals can be discussed. The notes/actions that are taken during the meeting is then e-mailed either to the entire team that participated or to a specific group, that is responsible to investigate possible solutions for a specific component further.
The actions are then revised and worked through by the designers until considerable changes have been made to the design of the product or module. Step four then corresponds to the follow-up meeting where the new design proposals are evaluated. New actions and changes on the revised components are discussed.
38 4.2.5 Implementation
The first thing to consider when implementing DFA is to attain a person of great knowledge of DFA. This individual should be the driver of the DFA work and should be able to address how people perceive the methodology, as it might be viewed as time consuming. However, the amount of time spent in the initial stage of design can reap savings in time in the later stages in the design.
At Company X, the most important aspect when implementing DFA was the acceptance from the management. However, there is a difference between accepting DFA and to be actively participating in the work. It was not until the management actively was participating as the result was requested and improvements could be made.
In addition to this, it is essential that the methodology is not misused e.g. to demonstrate how successful a product is. For example, Company X works with geometrical small components. This is reflected in the DFA2-aspect “tolerances” as a weakness for a considerable number of components. It is therefore frequently requested by the managers to change the aspect to reflect the size of the components so the product or module will receive a higher DFA2-index. However, this is not recommended by Interviewee X (2018). The work with DFA could be compared to the work of Lean and to actualize the result quickly and therefore take shortcuts will not result in an efficient Lean system. The work of DFA should be applied in a similar way.
4.2.6 DFA in the product development process
Company X’s development process is divided into ten tollgates, which are illustrated in figure 18. DFA has variables in gate two to gate five, i.e. from choice of concept until the design is set.
The initial DFA2-evaluation is done on a product level using the DFX-module in AviX, in gate two. The purpose of the initial DFA2- evaluation is to provide input to the selection of concepts. The concepts are created by the D&D department in collaboration with an external design firm. After a concept has been selected, an extensive DFA-analysis is done on a part level using the DFX-module in AviX (which is done before gate three). At gate four, the DFA-work should be revised with new design proposals and actions. At gate five the design is set. A final report is presented, and if there are any residual actions, these are presented as well.
At each of these gates a specific DFA-index is set and reported at the tollgate meetings. However, the obligation to meet the DFA-index varies, depending on if it is a “should” or “shall” requirement. A “shall” requirement means that the DFA-index must be met to pass the gate. This requirement is set in gate five, with an aggregated DFA-index at 70%. A should- requirement means that the gate can be passed, despite the fact that the DFA-index has not been met. However, the reasons why the index was not reached must be reported. These “should”-
39 requirements are set at gate two to gate four. For example, there is a “should” requirement of 60% in a DFA-index at gate three.
However, according to Interviewee X (2018), discussions can be held regarding if it is successful to only look at the aggregated DFA2-index for the whole assembly. The assembly time and the aggregated DFA2-index needs to be considered in respect to each other. In addition to this, the average index of each component needs to be studied, i.e. what is the lowest DFA2- index of a component that can be accepted.
At gate ten, there is a stage called “lesson learned”, which means that before a new project is initiated, the previous project is examined. This could include manufacturability and the previous aspect of DFA is taken in consideration and analysed.
Figure 18 Illustration of the product development process at Company X
According to Interviewee X (2018) it is important that the FMEA is done in parallel to the DFA-analysis, as the FMEA will create design improvements.
4.2.7 Decision model regarding DFA
The DFA-index (result of the DFA2-analysis) is presented to the sponsor group by the project manager at the tollgate meeting. The sponsor group then decides if the project will pass the gate. In other words, it is the sponsor group who decides if the product is sufficiently designed for assembly.
4.2.8 DFA initiator
At Company X, Interviewee X works as the DFA initiator. According to Interviewee X, it does not matter where the organisation’s DFA is initially positioned (e.g. at the production department or design department), since it does not matter to the end result. The main factor in order to succeed with DFA is to understand and systematize the work.
40 4.3 Scania
Scania is a Swedish automobile company with 45 000 employees that manufactures automotive products. Scania’s product portfolio includes heavy trucks, buses, engines and services (Scania Sverige, 2018).
The information in this section is based on internal documents provided by Scania, a study visit at Scania’s engine department (DEPB) in Södertälje and an interview with Christina Trång and Daniel Ekholm. Both Trång and Ekholm (2018) work at the global engine department at Scania.
4.3.1 Reasons for working with DFA
According to Tång, there are several reasons that Scania works with DFA. Firstly, DFA contributes to a simplified assembly, where assembly of a part can only occur in one specific way and there is no need for adjustments in the following processes. This leads to increased quality, less stop time and decreased cycle time. Secondly, DFA facilitates integration of parts and minimizes the number of variants. This leads to simplified logistics, less choices for the operator and reduced deviations. Finally, as quality increases the ergonomics become better for the operators.
4.3.2 Choice of method
Scania Engine Assembly function utilizes DFA in their daily work to support the principles of Scania Production System (SPS) for engine assembly. Scania is currently using a DFA- checklist with principles that correspond to the engine assembly. The purpose of the checklist is to make the products/modules more suited for the production. The checklist consists of 47 questions, which are digitally available. The questions are divided into four categories namely, product general, product specific, assembly process and after assembly (i.e. testing, painting and transportation). A snapshot of the DFA-checklist is illustrated in figure 19, which displays the questions for the product specifics (Scania, monteringschecklista, 2018).
Figure 19 illustration of a snapshot of the DFA checklist at Scania (Holmer 2018)
41 Each question in the checklist can be answered according to six options, which are awarded with different points:
Ø 4 points are rewarded to the option “Yes, the solution is better than previous”. Ø 3 points are rewarded to the option “Yes, the solution is similar to previous”. Ø 2 points are rewarded to the option “Yes, but the solution is worse than previous”. Ø 1 point is rewarded to the option “No, but the article can be introduced in production”. Ø 0 points is rewarded to the option “No, (re-design is needed)”. Ø No point is rewarded to the option “N/A”
A DFA-index is then calculated by dividing the total amount that the analysed part/component received by the maximum possible amount (Scania, monteringschecklista, 2018).
The DFA-checklist is linked to Scania’s internal Wikipedia system also called “the knowledge bank” (see figure 20) which is used as an inspiration for design solutions. The knowledge bank consists of design solutions for different components as well as illustrations of those solutions (Ekholm, 2018).
Figure 20 Illustration of Scania’s internal Wiki (Klingnell, 2014).
According to Trång (2018), the DFA-checklist plays a central role in how Scania Engine Assembly works with product development. One benefit of utilizing the checklist is that the learning curve becomes steeper, i.e. if a new person is introduced to a product development project it becomes easier to understand what has been done and become updated on the project. This is since possible since the open/closed issues that resulted from the DFA evaluations are stored in each project folder (i.e. entire the history of the work is available).
In addition to the DFA-checklist, Scania utilizes another checklist for the assembly process called the assembly-checklist. The assembly checklist is based on the DFA-checklist; however, it is more general and it is used at every test assembly in production (Trang, 2018).
Scania also has SES-documents (Scania Ergonomic standards) which consist of an extensive set of instructions to make the components more ergonomic (Scania, the use of SES design STD 4323, 2017)
42 4.3.3 Workflow- DFA analysis
Scania’s engine production does not conduct meetings which are only dedicated to the work of DFA or the DFA-checklist. However, DFA is a part of the meetings referring the overall design of the product, e.g. the layout meetings. Layout meetings are conducted by a cross functional team with individuals from the production department, design department and aftermarket department. At the meetings, 3D-models of the new design are presented and analysed by the team. The purpose of these meetings is to develop the design within a certain timeline before ordering the physical parts (Ekholm, 2018).
Scania also uses the software Delmia for digital test assembly. The software is used to analyse the product in the right conditions in production for a specific assembly order. In addition to this, Scania Engine Production holds physical test assembly meetings where the prototypes are tested and analysed in the development area at the engine production.
3.3.4 Implementation
To ease the implementation of DFA, there needs to be a dedicated resource who works with DFA full time (Ekholm, 2018). In addition, there also needs to be support from the management and a clear purpose of what the organization wants to achieve with DFA. This is since DFA could be used in many ways and if the purpose/aim is not clearly stated, the implementation will become difficult since the scope of the project will become too big (Trång, 2018).
4.3.5 DFA in the development process
Scania’s product development process (PD-process) consists of three sub-processes which are illustrated as three arrows of different colours; yellow, green and red (see figure 21). The yellow arrow corresponds the pre-development phase, which consists of three different areas namely, research, advanced engineering and concept development. The purpose of concept development is to create a concept that will meet the future requirements. Several solutions are then presented and the technical risks are analysed (Scania, the use of SES design STD 4323, 2017). According to Ekholm (2018), the global product engineer can contribute with input during the pre- development phase for the product, to ensure that the product is prepared for the process.
The green arrow relates to the phase product development. As illustrated in figure 21, after the target has been set and planning has been concluded, the new product should be developed according to DFA. (Scania, the use of SES design STD 4323, 2017). According to Trång (2018), a project goes through three generations before the serial production initiates. The three function generations are divided into configuration (Phase one), development (phase two) and verification (phase three).
The use of the DFA-checklist and the other activities related to DFA is initiated in the green arrow and are then iterated three times, i.e. the number of generation functions (Trång, 2018)
43 Finally, the red arrow phase is executed after the product has been introduced to the market.
Figure 21 Illustration of Scania’s product development process
4.3.6 Decision model regarding DFA
Scania uses an “escalating model” for the decisions regarding the work of DFA. This means that if the design is not proved to be sufficiently suited for assembly, the initial response for a production technician would be to talk to the responsible designer. However, if the designer is not willing to change the design, the case is escalated to a manager. Thereafter, a production technician then needs to present to the manager why the design did not reach its milestone and why it was not accepted. The manager is then responsible for accepting the request from the product technician to change the design so it becomes more suited for assembly (Ekholm, 2018).
4.3.7 DFA initiator
At Scania, the main driver of DFA is production. According to Trång (2018), it should be the production department who initiates the work with DFA, as the design department already has a considerable number of requirements to consider. However, Ekholm (2018) stresses the importance that DFA should permeate the entire organisation.
44 5. Current state analysis
In this chapter, the current state analysis of Company Y will be presented.
The current state analysis is based on several interviews with the employees of Company Y as well as observations and documents that have been provided from the Company Y’s intranet. The purpose with the current state analysis is to analyse the conditions to implement DFAA.
5.1 Company description
Company Y is a unit within a multi-international company, that manufacturers, develops and markets industrial automation equipment.
According to the Production technician manager, (2018) the products at Company Y are mainly assembled manually and 3-4% is assembled automatically. Currently Company Y is trying to increase the proportion of the automated assembly by introducing their own automation equipment. However, the current products and parts are not suited for automatic assembly.
5.2 Reasons for working with DFA
The reasons for working with DFA were fragmented among the interviewees. There was no common aim for why DFA needs to be implemented into the organization. According to the design engineer, the main reason for working with DFA is that the management has requested a way of working with DFA and has set an automation requirement for the new products. The global production engineer states the reason for working with DFA is to secure the safety of operators, increase quality and to decrease the cycle time in production. In addition to this, another reason is to be able to assemble their own products using their own automation equipment.
According to the Automation Consultant (2018), the main motivation to implement DFA is to be able to be competitive, as Company Y cannot compete with China and their low labor costs. The Production technician manager (2018) expressed that the motivation for implementing DFA is to handle the extensive number of engineering change orders (ECO) and to do it “right the first time”, as the ECO’s are both expensive and time consuming.
5.3 current way of working with ease for assembly
Currently, Company Y does not use a structured method to make their products more suitable for automatic assembly. To verify the design in respect to automation, Company Y conducts
45 frequent meetings in cross-functional teams where judgements of experienced engineers are shared.
5.3.1 Design Reviews
A design review is an activity within the product development process and is conducted in cross-functional teams, with individuals from service, design, maintenance, supply chain etc. There are two levels of design reviews; design review and technical design review. The purpose of the design review is to control the design status relative to the requirements i.e. functionality, reliability, producibility, service friendliness, quality, robustness, technical specifications and environmental aspects (Company Y intranet, 2018).
There are three phases where design reviews should be conducted, i.e. concept design, prototype design and the final review. The concept design review is a meeting where drafts of the design and CAD-models are presented by the designers. The design is then analysed by the participants. Thereafter, a conceptual solution is decided on and the prototype review is conducted. The prototype review refers to the solutions that will be applied to the prototype. The final review corresponds to the final prototype being presented to production, which is a result of the verifications from calculation, simulations and assessments from prototype testing (Company Y intranet, 2018).
The technical design is focusing more extensively on the design and the techniques. A central role in the technical design review is the cost and quality of the design. The decisions and the activities that the design review resulted in are documented in the end of the meeting (Company Y intranet, 2018).
5.3.2 Automation workshops
The automation workshops are a new concept at Company Y. The purpose of the workshops is to evaluate a part of the robot, such as a mechanical component in respect to the possibility to automate. The workshops are done in collaboration with designers and production technicians and are initiated by the team going to production and analysing how the mechanical component is assembled presently.
Models of the mechanical component are presented as CAD files, in the current assembly order. The participants then discuss current problems and issues and an estimated automation level is set for each component.
The potential drawback of this method is that it depends on the experience of the individuals and their capacity (Eskilander, 2001). Due to the unstructured procedure, it is difficult to avoid the discussion becoming time-consuming and biased. Since the automation level is estimated, the components might not be evaluated from the same criteria. This could also result in important assembly issues being missed.
46 5.3.3 AviX - DFX
Currently, the production department uses the software AviX for preparation in production. The licence of AviX’s DFX-module consisting of the DFA2-method was bought several years ago by the company. However, the licence was cancelled, due to lack of demand and usage.
5.3.4 The DFAA Project
According to Stephan Eskilander (2018) Company Y was one of the participating companies in the DFAA-project, that contributed to the dissertation “Design for automatic assembly- a method for product design: DFA2”. However, no recollection of this work could be found during this thesis study at Company Y. In addition to this, consultants working at Company Y have had lectures and workshops to educate employees about DFA.
5.3.5 Modularisation
Company Y is in the process of implementing a modular design, in which standardized interfaces are used. According to Eskilander (2018) it is preferable if the product is designed via modularisation when implementing a DFA method.
5.4 DFA in the Product development process
To be able to distinguish where DFA should have its variables in Company Y’s product development process, each gate needs to be analysed in respect to producibility. This is shown in the section below:
5.4.1 Gate model
Company Y’s product development process is based on Company Y’s Gate Model, see figure 23. The gate model is defined as a business decision model and is used as a conceptual roadmap for projects. There are seven goals with utilizing the model, namely it creates a business focus through a market and customer orientation, provides a basis for decision making, forms a common language for projects, generates transparency of the status of the projects, establishes cross functional teams, generates a continuously involvement of the decision makers and it creates control over the investments (Company Y, intranet, 2018)
Figure 22 Company Y’s product development process (intranet, 2018).
The Company Y Gate Model consists of 8 strict gates. Decisions are made at each gate about continuing investing or terminating the project (Company Y intranet, 2018). The gates are
47 described as follows:
• G0, corresponds to the initiation of the project. The main purpose with Gate 0 is that the project direction is ensured by the concerned parties. The meeting is conducted with the help of a checklist and the main project/product idea is presented (Company Y intranet, 2018). Manufacturing is ready to give an input concerning manufacturability and estimations of the production cost. • G1, target business relates to the approved results of the market preliminary study and the initiation of the project planning. Decision are taken regarding the product’s general properties. The purpose of the gate is to ensure that the right product is developed. At this stage, the manufacturing department should have sufficient knowledge of the offering and the impact it has on manufacturing (Company Y, intranet, 2018). • G2, target release relates to the approved results of the project’s preliminary study and the initiation of the project execution. There is an agreement of the manufacturability of the product and there are adequate resources to initiate the planned activities (Company Y intranet, 2018) The design concept has been chosen. However, if there are several parallel design concepts created, there is a possibility to postpone the concept selection. • G3 relates to the product being confirmed for release. The manufacturability and the cost of production is confirmed. The preparations for manufacturing is ready (Company Y intranet, 2018). The design is “locked” with the ambition that no design changes should be made. • G4 relates to the product being ready to be released. A prototype is created and the production cost is estimated (Company Y intranet, 2018). The product is released to production to test the production process. • G5 corresponds to the approval of the delivery and market introduction and preparations i.e. the initiation of the general sales and production of the product. The company is ready to release, manufacture and initiate sales (Company Y intranet, 2018). • G6 corresponds to the project being closed. At this stage, all R&D deliverables are completed. The product is totally operational. Lessons learned have been captured. • G7 relates to the business retrospective, which means that the production quality and costs have been evaluated and specific improvements have been implemented (Company Y intranet, 2018).
There are four roles that are associated with the gate model, namely the gate owner, the project manager, the gate assessor and the functional manager (Company Y intranet, 2018).
5.4.2 The checklist
Company Y utilizes a checklist, which is used as a preparation for the gate meetings. The checklist consists of several questions that need to be fulfilled. Each function has filled the checklist before the gate meeting. There are several questions in the checklist that correspond to manufacturability, e.g. “has the improvement for manufacturability been explored?” (Company Y intranet, 2018).
48
5.5 Decision making
Company Y does not currently have a clear decision model regarding DFA. The concepts are presented at weekly design reviews and automation workshops, in which the purchase department, production department and the calculation department have the possibility to give their input regarding the design. The designer takes every input into consideration and makes the final decision regarding the concept. The checklist can be seen as a tool used to ensure that the product can be manufactured.
5.6 Challenges to Implementing DFA
According to Automation Consultant (2018), Company Y is a large company and it may be difficult to change the working culture regarding DFAA. This is since Company Y has been building automation equipment for manual production for many years.
According to Global Production Engineering Manager (2018), it could potentially be difficult allocating sufficient resources for the DFA-evaluations. There are presently many different projects operating with strict time schedules. This is also concluded by production technician manager (2018) who state that it could be difficult to allocate more time for the product development projects and that the designers already are under pressure to lower the time from design to the manufacture stage.
The management has set an automation level of 90% for the new production being introduced. However, there is no clear procedure on how this should be met.
49 6. Results & Analysis
In this chapter, the results of the thesis will be presented. Firstly, the choice of method will be presented, which includes the results of the workshop, advantages respectively disadvantages with the method and a recommendation of the workflow conducting the DFA2-evaluation. Secondly, recommendations of how Company Y should work with DFAA will be presented. Thirdly, a recommendation of where in Company Y’s product development process that DFAA should have variables will be described. Finally, a decision model regarding DFAA and an implementation plan will be described.
6.1 Application of the DFA2-method
As early mentioned in the current-state analysis, Company Y is lacking a structured way for conducting their automation workshops. Therefore, a DFAA method was chosen and investigated, namely the DFA2-method created by Eskilander (2001) and provided by AviX DFX-module. The DFA2-method provides Company Y with a standardized way of working with making their products more suited for automatic assembly, addressing one assembly problem at the time.
6.1.1 Workshop- early implementation
Several workshops were conducted, also known as an early implementation phase, at Company Y. At the workshop, the current design of the subassembly of a mechanical component was evaluated. In addition to this, a new developed concept of the subassembly of the mechanical component was examined. The workshop was conducted in collaboration with people from the service department, R&D and production. The following steps were conducted before, during and after the workshop:
• Preparation • Evaluation of the current design • Evaluation of the new design concept • Proposing design changes of the new design
Preparation Before the evaluation, an appropriate product/module was selected to be analysed. A subassembly of a mechanical component was selected, which consists of 14 unique parts, illustrated in table 3.
50 Table 3 List of the parts in the current design of the subassembly of the mechanical component
Quantity Component name 1 Casting 1 Motor 2 Protection Screw 1 Stop Screw 1 O-ring 4 Washer 4 Hex Socket screw 1 Gasket 1 O-ring (rectangular) 1 Connection box 4 Torx screw 1 Gasket 1 Motor Cover 5 Screw
The assembly order of the subassembly was analysed in production and each assembly operation was listed in table 4. The assembly order is of importance, as the ability to answer the guidelines/questions in the DFA2-method is depended on the order in which the components are assembled. After this, each part of the subassembly was added manually into AviX. This procedure was time consuming and it is recommended that the articles are imported from Excel.
51 Table 4 List of the assembly order of the current design.
Evaluation of current design The subassembly was analysed on a part level according to the guidelines found in AviX. The results of the evaluation are illustrated in figure 25. Each part received an average DFA2-index and an assembly time. The subassembly received an aggregated DFA2-index of 56% and an aggregated assembly time of 425 seconds.
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Figure 23 Evaluation of current design of the mechanical component
By analysing the DFA2-index, the part with lowest index was identified. This included the casting, o-ring and motor subassembly. To improve the DFA2-index it is vital to re-design these parts. In addition to this, the assembly time indicated that the 5 pcs of torx pan head screws was the most time-consuming assembly operation.
Evaluation of the new design concept A new design concept of the sub assembly was also evaluated. The new design concept was created before the introduction of the DFA2-methodology as one of the new designs to facilitate a modular design and ease for automatic assembly. The new design is based on the current product/module. The new design consists of 9 unique parts, which are listed and illustrated in table 5. The major difference of the two concepts is that the connection box has been integrated into the motor subassembly, where gasket, o-ring, connection box and four torx pan head screws have been eliminated. In addition to this, the screw and the washer for securing the motor subassembly have been integrated into one component.
Table 5 List of the parts in the new design of the subassembly of the mechanical component.
Quantity Component name 1 New Casting 1 O-ring 1 Motor 2 Transparent plug 1 Stop Screw 4 Screw & Washer 1 New Gasket 1 New Motor Cover 4 Screw
The results of the evaluation of the new design concept are illustrated in figure 26. Despite the integration of several parts, the new design concept received a DFA2-index of 56%. This means that it received the same DFA2-index as the current design, i.e. no improvement from an automatic assembly point of view. However, the index could have been affected by the fact that the connection box, which had a high DFA2-index of 75%, was integrated.
The aggregated assembly time of the new design was 266 seconds and was 159 seconds faster
53 than the current design. This result indicated the importance of analysing the assembly index in relation to the assembly time.
Figure 24 Results of the new design concept
The results of the evaluation of both designs indicate that the DFA2-method is needed at Company Y to help the designer not to miss vital design features to make the products more suitable for automatic assembly. For example, the component gasket (part of the motor cover subassembly) received a lower DFA2-index than the current design. The motor subassembly also received a lower DFA2-index, this is due to the reachability guideline was given lower index, because of the new “deeper” design of the casting.
6.1.2 Advantages with the DFA2-method
According to a survey that was conducted among the participants after the workshop, there were several benefits of utilizing the DFA2-method, i.e.:
• User friendly The method was easy to learn and understand, despite some questions that were perceived as vague. The functions and applications in the DFX module were perceived as easy to learn.
• Provided a structured way of working The method provided a structured way of evaluating the subassembly, where one design issue could be dealt with at a time.
• Supported re-design The method had aspects/guidelines that supported re-design of the components, i.e. pointed at where the design improvements could be applied.
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• Supported cross-functionality The method supported cross-functionality since individuals from different departments were needed to answer the guidelines/questions, e.g. level of defects.
• Provided accountability The method provided accountability, since it is possible to delegate responsibility of the issues/actions for further investigation after the evaluation.
• Software solution Utilizing a software makes it easier to store the information and administrate, than using an Excel-spread-sheet or a checklist.
Finally, the method provided measurable effects, i.e. both aggregated DFA2-index and an aggregated assembly time. In addition to this, it provided a DFA2-index and an assembly time for each component.
6.1.3 Drawbacks with the DFA2-method
There were several drawbacks of the DFA2-method according to the participants in the workshops, which are listed below.
Ambiguous questions The questions/guidelines in the method were vague. For example, the guideline automatic gripper, level of defects was during the workshop interpreted differently by different participants. It is therefore recommended that Company Y clarifies each guideline, so no misinterpretations are made, otherwise the index will become biased.
Missing guidelines/questions There were several questions that would be beneficial to include in the method. This was also realised when analysing the current assembly of the mechanical component in production. The vision system of the robot in production had issues register components that had a shiny material or were dirty. This lead to the operator needing to use an extra component with a different material to register the position of the component. An example of a guideline that could be included to avoid the assembly problem is presented in figure 27.
Figure 25 Illustration of the criteria “When vision is needed”
55 Missing graphics In AviX, the BOM-list that illustrates all the components is not visible at all times in the evaluation, which increases the risk that the user evaluating could analyse the wrong component in the BOM-list.
Does not support CAD The software does not support CAD, which makes it difficult to analyse the component more precisely.
6.1.4 Recommended Workflow
Based on the workshops conducted at Company Y and the benchmarking, a recommendation of the workflow of DFA2-evaluations could be created. Ericsson and Company X had similar workflows regarding the DFA2-analysis. Therefore, a comparable workflow of the DFA2- analysis is recommended:
• Step 1: Preparation - Import BOM-list into AviX. Set components into a theoretical assembly order.
• Step 2: Evaluation - Evaluate each component according to the guidelines. Record actions and delegate responsibility if needed.
• Step 3: Analyse results of evaluation - Rank components to either assembly time or assembly index.
• Step 4: Make improvements - Follow action list . • Step 5: New Evaluation - When considerable design changes have been made - revise the design, record new actions.
• Step 6: Follow-up meeting • Maintain
Before the evaluation, it is recommended that Company Y assigns a person to act as a moderator. This individual will decrease the discussion to a minimum and act as an expert of the method, to prevent misinterpretations of the questions/guidelines.
Step one relates to the preparation of the evaluation, which was included in both Ericsson’s and Company X’s workflow. The components are imported (via excel) or added manually into AviX, in the correct assembly order. If there is no available assembly order, a theoretical
56 assembly order is used. If CAD files are available, these should be presented as well (Ulin, 2018).
Step two corresponds to the first evaluation. Each component is evaluated according to the guidelines/aspects provided by the method. It is recommended that the extended version of the method is used, to avoid assembly issues being missed (Solme, 2018). Actions are noted in AviX for each component that is rewarded with one point in AviX. A responsible person is also assigned to investigate the action further (if needed). It is also recommended that the guidelines rewarded with 3 points are commented. However, guidelines rewarded with 9 points should not be processed. As mentioned earlier, the DFX-module includes the possibility to grade each problem found in the evaluation according to low, medium and high (also known as minor, intermediate and major). This is done by Ericsson and helps the designer to deal with the most urgent problem. It is therefore also recommended to be utilized by company Y.
It is recommended to have limited discussions during the evaluation (Interviewee X, 2018). This was recognised during the workshops as the evaluation became too time-consuming.
Step three corresponds to the phase when the evaluation has been completed and the results are available. Each component is then ranked according to either DFA2-index or assembly time (Interviewee X, 2018). The moderator then transcribes the actions and e-mails the corresponding participants.
Step four relates to the work performed according to the action list based on the DFA2- evaluation. It is recommended that the designers communicate/meet the people that have been assigned to investigate specific aspects.
Step five relates to a new DFA2-meeting, when sufficient design changes have been made. In this step, a new revised evaluation is made based on the previous evaluation. Old actions are now closed and new ones are recorded and delegated.
Step six corresponds to the number of follow-up meetings that are conducted to make the product/module sufficiently designed for automatic assembly.
6.2 Departments working with DFAA
According to researchers in the field of DFA, the work of DFA should be done in cross- functional teams to support concurrent engineering. This is to prevent the phenomenon “over the wall” (Filippi and Cristofolini, 2010). All three benchmarking companies include production engineers and design engineers in their DFA-work. According to Eskilander (2001), it is recommended to also include engineers from the purchasing department and quality department. According to Interviewee X (2018), by involving the purchasing department, the DFA2-team will receive knowledge of which manufacturing methods are currently available for possible “make or buy decisions”.
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According to Boothroyd and Dewhurst (2011), by introducing DFA, the quality of the components is increased and the number of assembly defects is decreased. It is therefore important to receive feedback from the quality department if there are still occurring assembly defects in production, as it can be an indication that there is a guideline missing.
Therefore, it is recommended that the department that should be participating in the DFA2- work are: • Production (technicians, assembly personnel) department • Design department • Quality department • Purchasing department
A recommendation from Solme (2018) is that only one individual from each department should be present during the meeting. This is to facilitate cross-functional teams, without the team becoming too large, since too large groups will make it difficult to make quick decisions. Furthermore, it is important that each department should be allowed an equal voice as the other departments representative at the meetings, which can become difficult if individuals from one department is over representative (Solme, 2018).
The initiator of the DFA work/meetings should, according to Ulin (2018), come from the production department. This was also concluded by the interview from Scania. This is since the design department already has extensive requirements to take into consideration and that the main advantages of the work of DFA will be utilized by the production department. Eskilander (2018) states that it is important that there are individuals that have the work of DFA within their work title. This is to ease the implementation of DFA. According to Eskilander (2018), the implementation will be most successful if the design department runs and owns the work of DFA, however expresses that it can also be successful if the production has the responsibility of DFA. Based on these arguments, it is recommended that the production department has the responsibility of the work of DFAA at Company Y.
6.3 DFAA in the development process
According to researchers, DFA should be applied as early in the design process as possible (Boothroyd, Dewhurst and Knight, 2011). Based on the benchmarking and the current state analysis, a recommendation of where in the product development process DFAA should have variables, could be presented. This is illustrated in figure 28.
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Figure 26 DFAA in Company Y’s product development process
During the early phases of the product development process it is recommended that Company Y states the key performance indicators (KPIs) regarding the aim of DFAA. Preferably in the initiation phase of the project, i.e. in gate 0. The importance of well-stated goals is expressed by Frohm (2008) as “The main reason that an automation project ends in failure is unrealistic or undefined objectives” (Frohm, p 65, 2008). The aim/result of DFA2-method can be expressed in various ways, which is described further in section 6.4.
Company X utilizes the DFA2-method on a product level to facilitate concept selection. To choose the design concept that is most suited for automatic assembly, it is therefore recommended that Company Y utilizes the DFA2-method before gate two, where the concept is chosen.
Both Ericsson and Company X, utilize the DFA2-method on a part level. This can be done when the overall concept has been chosen, i.e. after gate two until the design is “locked” in gate three. Each component is analysed according to the DFA2-method. At Company X, the design can only be accepted if it has reached a specific DFA2-index, which is set to 70%. This minimizes the risk that components that are not suited for automatic assembly is passed to production. It is therefore recommended that Company Y chooses a measurable result, based on the DFA2-method at gate three (illustrates in red in figure 28). This could be either a DFA2- index, assembly time or a grading scheme.
6.4 Decision model regarding DFAA
Currently, there is no decision model that emphasises on making the products more suitable for automation at Company Y. The Global Production Engineering Manager (2018) at Company Y stressed the fact that they do not have a specific individual that has the responsibility of ensuring that the products are sufficiently designed for automatic assembly. Instead, Company Y is basing their decision making regarding DFAA on experienced engineers and estimates a DFAA-index on each component. One possible drawback of this is that it is difficult to draw accurate decisions based on estimated values.
A decision-model will facilitate the decision to determine if the product/module is sufficiently designed to be automated. This is to avoid the risk of either under-automating or over- automating, which according to Synnes and Welo (2015) could decrease the competitiveness.
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According to Eskilander (2001), the DFA2-method could be used to provide valuable information for decisions regarding product development. The DFA2-method provides measurable values for automatic assembly, namely the DFA2-index, the grading scheme (i.e. actions are graded according to minor, intermediate and major) and assembly time.
According to Eskilander (2018) and Solme (2018), there is no “golden rule” to which DFA2- index that should be sufficient for the product/module in respect to a successful automation. According to Eskilander (2018), the allowed index varies depending on the company and what type of failure rate that the company allows. Solme (2018) states that to increase the DFA2- index from 50% to 55% yields a higher effect in respect to the number of decreased faulty products, compared to working on increasing a DFA2-index from 80% to 90%. This is illustrated in the regression analysis below (figure 29). Company X currently works with a DFA2 index of 70%, however used to work at a level of 40-45% when DFA2 was first implemented.
Figure 27 Regression analysis (Solme, n.d)
In addition to this, the assembly could be measured according to a grading scheme, i.e. actions taken from the DFA2-evaluation which are graded according to minor, intermediate and major and then only allowing e.g. 15 majors at a specific stage in the process (Ulin, 2018). Finally, the aggregated assembly time can be used as an evaluation of the design in the beginning of the project.
Eskilander (2018) concludes that the DFA2-index should be analysed in association to the assembly time. This is due to the scenario that if a component that is integrated had received a high DFA2-index, the overall DFA2-index of the design will be lowered. However, the decrease in the assembly time will indicate that the design has improved.
60 The two former measurements emphasise more on making the product suited for automatic assembly. The latter is a key indicator which is more utilised to calculating the cost. The assembly time or the assembly cost needs to be accurate enough to be helpful and since no evaluation can include all parameters on an assembly operation, the assembly time or cost may be unreliable (Eskilander, 2001). Based on these measurable values, a recommended decision model has been made, which is illustrated in figure 30.
Figure 28 Recommendation of a decision model regarding DFAA According to Ericsson and Erixon (1999), modularization facilitates the work of DFA, and minimizes the risk of sub-optimization. Company Y is currently in the initial phases of modularising their product assortment. Therefore, the recommended decision model regarding DFAA is based on having a modular product architecture.
According to von Yxkull (2018), to avoid the product variants being sub-optimized, a module owner is required. The module owner has the responsibility over all module variants across the product families. The module owner is responsible over quality, cost, functionality and manufacturability (including DFA) etc. (von Yxkull, 2018). The module owner presents the design to the DFA2-team. The DFA2-team corresponds to the cross-functional team that analyses the design according to the guidelines in the DFA2-method, where the actions are used as a directive to the module owner.
The concluding result of the DFA2-method is then presented by the project manager to the automation council (e.g. as a part in the tollgate checklist). The automation council relates to the team that has the responsibility to create an automatic assembly process. Finally, the Business unit management has the responsibility to take the decision if the automation requirements are met.
6.5 Implementation plan
Bruke and Carlson (1987) stated several steps to ease the implementation of DFA. Based on this, workshops held at Company Y, the current state analysis and the benchmarking, an implementation plan can be recommended:
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1. Provide a DFA overview to senior management 2. Define objectives and a vision with DFA 3. Choose a DFA champion/coordinator 4. Choose a pilot project (according to Eskilander (2001) preferably the new modular concept). 5. Establish the individual members and the structure of the team. 6. Coordinate the training. 7. Initiate a workshop. 8. Maintain.
All three benchmarked companies stressed that the most important factor to implementing DFA successfully was the involvement of the management. Moreover, that the management actively participated in the work of DFA and asked for results. According to Ahm and Fabricius (1990), the management also needs a fundamental understanding of the work of DFA and that it is resource-intensive in the initial phases of the product development, so adequate resources could be allocated. Based on the interviews with employees at Company Y, this could be difficult, since there are many projects with strict time schedules. The designer is currently pressured to lower time of the design to manufacture stage.
Eskilander (2018) expresses that it is important that the organisation states a clear reason for why they want to work with DFA. With other words, what the firm wants to achieve with the work of DFA. This was also stressed by the two companies Ericsson and Scania. At Company Y, the reason, aim and purpose for working with DFA, were fragmented among the interviewees. The importance in striving towards a common goal is that all employees feel involved and engaged to achieving the specific goal. This is to increase the motivation of DFA. In addition to this, Company Y should have a common vision with DFA that needs to be accepted by the entire organisation and the goal should be in accordance with SMART.
Many of those who were interviewed, had a knowledge of the term DFA, however was not accustomed to a structured method. At the workshops held at Company Y, the discussions were time consuming and the questions/guidelines were often misinterpreted. It is therefore important to choose a DFA champion or coordinator to control these issues.
62 7. Discussion
This chapter will be used to draw the conclusions, this by synthesizing the results and connecting them to the literature. The four sub-research questions will be discussed.
When analysing the result of the workshop it becomes clear that Company Y is in need of a structured DFAA method. As shown in the current state analysis, the company lacked a structured method, which according to researchers could lead to problems related to automatic assembly being missed. This was also verified in the workshop, since the new design of the mechanical component, had received the same DFA2-index as the current design of the mechanical component. However, the result of the DFA2-analysis could be affected by the guidelines being misinterpreted and treated differently at the different workshops occasions.
The recommendation of how a structured DFAA method should be applied is based on investigations of several workshops and a benchmarking with three manufacturing companies. The benchmarking gave insights/recommendations of how a structured method should be applied at the respective company. At the workshops, these recommendations gave the possibility to verify the procedures and find the best practices for Company Y.
Company Y is currently trying to make their existing products more suitable for automatic assembly. The product that was analysed at the workshop was the current design of a mechanical component. However, as researchers have pointed out and stated by the companies Ericsson and Company X, the DFA2-method should be applied on new developed designs to yield the best results. One could therefore ask if it will be beneficial to apply the method on the current products, trying to make them more suited for automatic assembly.
The recommendation of where in the development process Company Y’s DFAA should be implemented is mainly based on the benchmarking. However, despite all three manufacturing companies being similar to Company Y– every company has their own procedures and therefore, their best practices might not be of best practice at Company Y. The study gave pointers of an early adaption of DFAA. The more the product change according to the work of DFA2, the more it will affect the entire supply chain of the company, e.g. the work of subcontractor. This also means that more functions and departments might need to be involved at the DFAA-evaluations.
The result of what decision model most suited for Company Y, could not be verified in the study. The recommendations were solely based on the literature study and interviews. However, the current state analysis indicated that there is a need for a decision model, since most of the decisions are made on personal experience.
63 8. Conclusions
In this chapter, the conclusion of the thesis will be presented, where the research questions will be answered. In addition to this, the limitations, implications and future work will be discussed.
7.1 Concluding the research questions
The purpose of this master thesis was to investigate how Company Y should implement DFAA and how they could make the products and components more suitable for automatic assembly and increase the application of automation in production. Based on the purpose, a main research question was formulated:
v How should Company Y implement DFAA, to increase the possibility to automate the assembly process?
To answer the main research question, four sub-questions were formulated. The answers to these questions are presented below:
Ø How a could structured DFAA method be applied?
A recommendation of how the DFA2-method should be applied was created. This included all the steps that should be done before, during and after a DFA2-analyis:
• Step 1: Preparation - Import BOM-list into AviX. Set components into a theoretical assembly order. • Step 2: Evaluation - Evaluate each component according to the guidelines. Record actions and delegate responsibility if needed. • Step 3: Analyse result of evaluation - Rank components to either assembly time or assembly index. • Step 4: Make improvements - Follow action list • Step 5: New Evaluation - When considerable design changes have been made. - Revise the design, record new actions • Step 6: Follow-up meetings
64 Ø Which departments should be involved and what competence is need?
In the early implementation of DFA2, it is recommended that the production (technicians, assembly personnel) department, design department, quality department and the purchasing department should be participating in DFA2-evaluations. In addition to this, it is preferable that only one individual from one department is representative at the meeting, in order to facilitate quick-decision making.
However, once DFA becomes rooted in the company, more functions in the company’s supply chain will become affected. This means that more functions and departments might need to be included in the work of DFAA.
It is recommended that the responsibility of the implementation (main driver) of DFAA should be from individuals representing the production department. This is since the design department already has extensive requirements to take into consideration and that the main advantages of the work of DFA will be utilized by the production department.
Ø Where in the development process should the early adaption of DFAA be implemented?
The implementation of DFAA should be done as early as possible in the development process. Initially, KPIs should be set before the initiation of the project. Thereafter, the evaluation is done on a product level for input for the concept selection, which is done before gate two. When the design concept has been chosen, the DFA2-method is done on a part-level, which is done until the specific measurable result is met. This could be a DFA2-index, assembly time or according to a grading scheme. This should be met before the design is “locked”, i.e. in gate 3.
Ø How should the decision model look like?
There are three measurable values that Company Y could utilize to base their decisions on, namely, DFA2-index, grading scheme (actions graded according to minor, intermediate and major) and assembly time. Based on the measurable values, a recommendation of a decision model could be made, which is illustrated in figure 31 below.
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Figure 29 Recommendation of a decision model regarding DFAA It is evident that the organizational and new way of working due to DFA or DFAA will lead to a different product flora. It will affect the number of parts and the affect the opportunities to create new variants. Furthermore, all methods are not without consequences and production will be affected both upstream and downstream. The work of DFA/DFAA will not yield the anticipated result if not the entire chain of activities is considered. The work of DFA/DFAA and concurrent engineering should be viewed as an organizational working strategy (Onori, 2002).
According to Maffei, Neves and Onori (2013), the reason for organizations ignoring the opportunity to invest in new product technology is the business models that are used presently has not improved since the 1990s. With other words, to succeed with the work of DFAA, to adopt automation, company Y needs to accommodate their business model.
7.2 Limitations
This thesis investigated how DFAA should be implemented in the development process. The literature used in this study was extensive, however little of what was found considered the negative properties of working with DFA, which could indicate that the research is somewhat biased. In addition to this, implementing DFAA affects the entire value chain and it requires the organization to make an extensive investment. However, this aspect was not included in the study.
Several DFA methods include a cost analysis for comparison of designs (e.g. DFMA and DFA2). However, due to limitations of the scope of the analysis this was not included in the master thesis.
7.3 Implications
The theoretical implications and the managerial implications have been identified through the conclusions. These are presented in the section below.
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7.3.1 Theoretical implications
The study has contributed with knowledge regarding how to implement DFAA. This has not been extensively investigated by researchers and the thesis aimed to fulfil this gap. The main theoretical implications found during the thesis is presented below.
v There are several DFA methods commercial available to use (Eskilander, 2001) In this thesis two methods were investigated, DFMA and the DFA2-method, however only the latter method was tested in practice. The research regarding how to use methods to evaluate products/modules have been extensively researched. However, the workflow of the methods has not been considerably investigated. Therefore, a recommendation of a workflow of the DFA2-method have been created.
v According to Boothroyd, Dewhurst and Knight (2011) a claimed implication of implementing DFA is that it is not enough time for designers to apply the method. This was also realised during the early implementation of the DFA2-method and the DFA2- method was experienced as time consuming. However, to reap the benefits of the later stages when the prototype is created the need to allocate resources and time in the earlier stages of design is needed.
v Having a clear purpose with DFA to simplify implementation have been highlighted by Bruke and Carlson (1987). Frohm (2008) also states that the main reason that automating projects fail is that the objectives were not realistic. It is therefore recommended to have a clear purpose and reachable objectives regarding DFAA.
7.3.2 Managerial implications
The managerial implications found in the thesis are given in the section below.
v Eskilander (2001) expresses that DFAA should be applied in the early design stages. However, he does not investigate extensively how to apply the method in the different stages of the product development process. The thesis aimed to give a recommendation for companies of where in the product development the DFAA should have variables and how it should be applied in the different stages.
v As earlier mentioned, DFAA comes with several benefits, however to implement a new way of working with product design requires patience, since the method is not implemented at once. Therefore, a recommendation of which departments that need to be involved in the initiation of DFAA-work have been made. However, since DFAA will impact the entire organisation, it is recommended that a culture of DFAA is developed within the entire organization.
67 v In order to successfully implement DFAA, a clear decision model is required. This is to avoid the risk of either over-automating or under-automating. This became evident in the study and it is recommended that organizations create a decision-model to control that the products are sufficiently designed for automation.
7.4 Future work
In this study, it became evident that Company Y needs a structured way of working with DFAA. To successfully implement DFA, there need to be dedicated resources to maintain the work. DFAA should be seen through a holistic point of view as it will affect the entire organization. Therefore, it is of importance for future research that Company Y involves the entire supply chain in the work of DFAA. This is to introduce a feedback-loop to continuously improve the work of DFAA. This will also lead to the DFA2-method being improved, as the issues found in assembly can correlate to a guideline missing.
Company Y is in the initial phases of introducing modularity, and based on the concluding remarks of the thesis, it would be interesting to investigate where in the configuration of platforms and modules DFAA should have its variables. In addition to this, Company Y should initiate their work with DFAA, by prioritising their modules, i.e. which one that are stable over time and has a high volume. With other words, apply the method on their most important modules.
During the thesis, an early implementation of the DFA2-method was conducted. However, some drawbacks of the methodology were found. It is therefore recommended that the methodology is improved, e.g. guidelines are clarified, so no misinterpretations are made. In addition to this, the cost analysis related to the design should be investigated.
Finally, based on the concluding remarks stated in the thesis, it’s important that Company Y develops a clear purpose and aim with DFAA. In addition to this select the appropriate measurable values based on the DFA2-method, to provide a basis for the decision-making.
Lastly, the DFA2-method includes a cost analysis. It is therefore recommended for future research to investigate how this could be used to compare designs.
68 References
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Stone, R., McAdams, D. and Kayyalethekkel, V. (2004). A product architecture-based conceptual DFA technique. Design Studies, 25(3), pp.301–325.
69 Synnes, E. and Welo, T. (2015). Design for Automated Assembly of Large and Complex Products: Experiences from a Marine Company Operating in Norway. Procedia Computer Science, 44, pp.254-265.
Books
Bolmsjö, G. (2006). Industriell robotteknik. 3:e ed.
Boothroyd, G., Dewhurst, P. and Knight, W. (20011). Product Design for Manufacture and Assembly Second Edition Revised and Expanded. 3rd ed. Switzerland: Marcel Dekker AG, pp.1-20
Collis, J. & Hussey, R. (2014). Business research: a practical guide for undergraduate and postgraduate students. New York: Palgrave Macmillan Higher Education.
Crnkovic, I., Asklund, U. and Dahlqvist, A. (2003). Implementing and integrating product data management and software configuration management. Boston: Artech House, p.214.
Filippi, S. and Cristofolini, I, (2009). The design guidelines collaborative framework. London:springer, pp.5-10
Groover, M. P., 2001. Automation, Production Systems, and Computer-Integrated Manufacturing, 2nd ed., Prentice Hall, Inc, Pearson Education. ISBN 978-0132393218
Kalpakjian, S. and Schmid, S. (2009). Manufacturing Engineering and Technology. 6th ed. New York: Pearson, p.1083.
Nof, S., Wilhelm, W. and Warnecke, H. (1997). Industrial assembly. London [etc.]: Chapman & Hall.
Rostek, K. (2015). BENCHMARKING COLLABORATIVE NETWORKS - A Key to SME Competitiveness. [S.l.]: SPRINGER INTERNATIONAL PU, pp.33–34.
Thesis
Egan, M., “Design For Assembly” In The Product Development Process- A Design Theory Perspective”, Thesis for the degree of Licentiate of Engineering, Chalmers.
Eskilander, S. (2016). Design For Automatic Assembly- A Method For Product Design: DFA2. Ph.D. Royal Institute of Technology.
Hallin, A. and Karrbom Gustavsson, T. (2015). Project-ledning. 2nd ed. Stockholm: Liber, pp.53-178.
70 Klingnell, D. (2014). Utveckling av arbetsmetod för DFA. Master of Science Thesis Royal Institure of Technology.
Frohm, J. (2008). Levels of Automation in Production Systems. Chalmers University of Technology, Sweden. ISBN 978-91-7385-055-1
Internet sources Avix.eu. (n.d.). AviX DFX – Design for Assembly made easy. [online] Available at: https://www.avix.eu/en/our-products/avix-dfx/ [Accessed 25 Jan. 2018]
Dean, J. and Susman, G. (1989). Organizing for Manufacturable Design. [online] Harvard Business Review. Available at: https://hbr.org/1989/01/organizing-for-manufacturable-design [Accessed 9 Apr. 2018].
Dfma.com. (n.d.). DFMA® Software DFA Product Simplification. [online] Available at: http://www.dfma.com/pdf/dfadescription.pdf [Accessed 25 Jan. 2018].
Ericsson.com. (2018). About Ericsson- Corporate Information. [online] Available at: https://www.ericsson.com/en/about-us [Accessed 27 Feb. 2018].
Ericsson.com. (2018). Base stations and networks. [online] Available at: https://www.ericsson.com/en/about-us/sustainability-and-corporate- responsibility/responsible-business/radio-waves-and-health/base-stations-and-networks [Accessed 1 Mar. 2018].
IFR International Federation of Robotics. (2017). IFR forecast: 1.7 million new robots to transform the world´s factories by 2020. [online] Available at: https://ifr.org/ifr-press- releases/news/ifr-forecast-1.7-million-new-robots-to-transform-the-worlds-factories-by-20 [Accessed 29 Mar. 2018].
Manenti, P. (2014). THE FUTURE OF MANUFACTURING MAXIMUM FLEXIBILITY AT COMPETITIVE PRICES. SMC World, pp.6-21
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71 Appendix A: Interview Guide – Company Y
Interview Guide- DFAA
Purpose: Employees of Company Y are interviewed with the purpose to identify the researchable problem. Furthermore, to receive information regarding the product development process at Company Y and the different employee’s involvement in the process.
The master thesis is done as a final project to receive a mater in Production Engineering and Management at KTH, Royal Institute of Technology. The University requires investigating a phenomenon for the academia. The report will not publish sensitive information and the confidentiality agreements will be kept.
Introduction:
• Is it okay for you if this interview is recorded?
• Could you please present yourself briefly?
• What is your title and what are your job assignments?
• How long have you had this position?
• What department do you belong to?
Product development and manufacturing
• Which responsibilities do you have in the PD process?
• Looking at the product development in relation to manufacturing in general what would you like to improve?
• What changes have you seen in the way of working with product development in relation with manufacturing?
• Is there currently a method or a way of working to make the product more suitable for automatic assembly?
o Test prototype or product? o Virtual automation testing? o Meetings?
72 DFA/DFAA in general
• Are you familiar with DFA? Or DFAA?
• Why is it so difficult to automate the assembly of robots?
• What would you say is the motivation of implementing DFAA?
• What would you say is the benefits utilizing a method such as DFAA?
• In your view, what are the difficulties in implementing DFAA?
• Where in the development process should you work with DFAA?
• How cross functional do you experience work to be regarding making products more suited for automatic assembly?
• Which departments should be involved to make products more suitable for automation? o What competence is needed?
• Who decides when the product is sufficiently designed/suited in respect to assembly?
o How do you ensure that the changes of the concept/prototype do not impair the ability to assemble the product automatically?
o What expertise does should the decision-making person/team require?
Interview guide Benchmarking
The interview guide for the benchmarking interviews had similar questions to the questions asked at Company Y. Therefore, only the added questions will be presented in the section below.
DFA Method:
• Does DFA play a part in your work? If so, how do you work with DFA?
• Why have you chosen the method/system you have?
• Do you utilize the same method throughout the entire product development process? o If so, why? o If not, why? And how does it change?
• How frequently do you use the method?
73
Implementation of DFA:
• What are the first things an organization need to consider when implementing DFA?
• What are the first things an organization need to consider when implementing DFA?
• What effects have you seen after implementing DFA?
• What are the benefits with DFA?
• What are the drawbacks with DFA?
74 Appendix B: Gantt-chart
75 TRITA ITM-EX 2018:543
www.kth.se