Manufacturing Processes, Part 4

Study Unit Manufacturing Processes, Part 4

By Thomas Gregory Manufacturers must organize and manage resources to maximize the profitability of their operation. Global competition has caused significant changes in the way business is con- ducted and managed, especially in two areas: manufacturing

standards and product quality. Increased emphasis on Preview Preview product quality means that almost every manufacturer must now rely on a quality assurance (QA) program and embrace defined quality standards. Controlling the manufacturing process requires extensive use of technical communication and management tools, many of which are directly implemented by technicians. In fact, manufacturing technicians can significantly influence their company’s ability to prof- itably produce high-value goods.

When you complete this study unit, you’ll be able to • Understand and describe the basic functions of management and the principles on which work is organized in a manufacturing business • Understand and describe various types of production control systems • Describe the basic concepts behind modern production systems • Explain how modern QA systems affect the manufacturing processes and product and process quality • Understand how modern network-based communications technologies will affect the manufacturing process now and in the future

iii Contents Contents

AN INTRODUCTION TO MANUFACTURING ORGANIZATIONS 1 Scientific Management 3 Early Work Organization 3 Factors of Production 11

MANUFACTURING FORMATS 14 Types of Manufacturing Production 14 Equipment Layout 19

AUTOMATION AND MECHANIZATION 29 Evaluating Automation 30 Automation Strategies 34 Industrial Robots 35

MANUFACTURING MANAGEMENT SYSTEMS 46 Just-in-Time (JIT) Manufacturing 47 Lean Manufacturing 49 Quality Management and Quality Assurance Systems 51 eManufacturing 60 The Future of Manufacturing 64

SELF-CHECK ANSWERS 67

EXAMINATION 69

v Manufacturing Processes, Part 4

AN INTRODUCTION TO MANUFACTURING ORGANIZATIONS

In your previous studies you’ve learned about many important aspects of manufacturing materials and processes, and factors that determine efficient and effective production practices. For any given product, a wide variety of material choices and manufacturing methods are available, but in a practical manufacturing environment, these choices sometimes come with constraints that are beyond the engineer’s or technician’s control. A manufacturing company must organize and manage its resources in a way that maximizes the value of those resources and the profit from production. The most efficient organization of a manufacturing business depends on many factors, including business location, type of product, production volume, availability of skilled labor, government regulations, and market competition. In recent years, especially since access to the Internet became widespread after 1994, communications and data management techniques have become more sophisticated, resulting in globalization of industries. Globalization has resulted in greater marketing opportunities for U.S. companies and, perhaps more importantly, for other businesses located in less developed countries around the world, such as India, China, and Southeast Asia. Along with an expanded market, U.S. and European companies are also experiencing greater competition in businesses where manual labor or lower-level technical help is significantly less expensive abroad.

1 You’ve probably noticed the number of products now using metric dimensions, and seen product directions printed in multiple languages. American manufacturers are adopting international measurement standards to gain more access to international markets. QA programs are spreading, too. We’ve had QA programs in specific industries in this country for many years, such as the nuclear power industry. Today, many companies are adopting internationally recognized QA systems such as ISO 9000. As a manufacturing technician, you need to be aware of industry trends that will affect both your job and your company’s ability to produce high-value goods. You’ll undoubtedly work under a QA system that regulates manufacturing processes, and you may be called on to use more extensive technical communication and management tools. In this unit we’ll discuss some of the more important concepts that relate to managing production systems. Operations research is the general term used for the study of management of manufacturing processes, with the general goal of maximizing the effective use of business resources. As we go to our jobs on a regular—probably daily—basis, we tend to overlook some of the larger aspects of what we do, why we do it, and who tells us how to do it. We have skills we bring to a job, and our employer expects us to use those skills to the best of our ability to further the company’s goals. Many jobs have written job descriptions, which are detailed descriptions of all the responsibilities and skill requirements a particular position demands. These documents are usually written with the cooperation of the management, the direct supervisors of the employee, and the human resources department, which oversees the legal aspects of hiring and firing personnel. Our work is organized for us, and we seldom give any additional thought as to how we got to where we are. However, by studying developments in work organization and the evolution of modern manufacturing organizations, we can learn how all of the pieces fit together to make a competitive and profitable organization in an increasingly global economy.

2 Manufacturing Processes, Part 4 Scientific Management

The term scientific management was first applied to early researchers’ attempts to examine the tasks done by workers in early factories, and to use the analysis of the results to improve the organization of work. Frederick W. Taylor (1856–1915) was one of the early pioneers in this area, and his rigorous observations and astute analyses were recognized as having important consequences for the organization and management of factories of his day. Eventually, his and others’ work evolved into the recognized discipline of industrial engineering, which is an important engineering category today. In the next section we’ll discuss how the organization of work evolved from early manufacturing models to today’s modern factory, and how managers have attempted to improve the productivity of various work arrangements.

Early Work Organization

The work of people has been organized in many ways since before written history, perhaps even beginning with the separation of people into “hunters,” “gatherers,” or “farmers.” Early communities were governed by a chief or other leader who made the decisions on expected work “assignments” and the division of goods produced, captured, or otherwise acquired by the group. In a sense, this was the first management structure developed by humans: an autocracy (rule of one) based on physical power. As societies became more complex, people’s work became more specialized, and more members in a group were con- cerned with a particular product or developing certain skills. Think about the people who were the first farmers, potters, weavers, or sword makers. For small groups, individuals could probably do all of the tasks necessary to manufacture their products. However, as the number of people in a group, community, or state grew, a demand for increased quantities of products resulted in a further separation of duties and skills. In medieval times, the concept of apprenticeship arose, where younger members of a group or family learned the skills of the master by first doing menial tasks, and later more complex and important tasks as their skills increased.

Manufacturing Processes, Part 4 3 Apprentices were the beginners in a trade, journeymen were intermediate-level skilled workers, and masters were the experts. We still apply these categories to many trades now in existence. Work in these organizations was directed by the master, and many masters of a trade in a given region were loosely governed by a guild, an organization of craftsmen engaged in similar occupations who communicated informally about issues related to their businesses (Figure 1).

FIGURE 1—In medieval times, apprentices pro- gressed from trainees to Trade Guild journeyman level and eventually joined the Master Master Master loose confederation of Mason Wright Carpenter masters within a guild.

Journeyman Journeyman Journeyman Mason Wright Carpenter

Apprentice Apprentice Apprentice Mason Wright Carpenter

Organization of work on a larger scale was probably first done with the development of class structures in society. Increasing division of labor in larger societies was caused by the development of a government in which the principal ruler didn’t have direct authority over individuals, but instead entrusted supervision and authority to appointed managers or bureaucrats. Distinct economic classes soon developed that determined who did what, and under whose direction. Children born into an economic class were likely to stay there, and families were often confined to specific occupations, passed down from father to son for generations. If you think about our personal naming conventions, you can see remnants of this practice in surnames such as Potter, Smith, Weaver, or Cook.

4 Manufacturing Processes, Part 4 The Romans wrote some of the first management texts about the division of labor on their estates. Their surviving texts specify the desired number of supervisors, farmhands, animal tenders, and slaves required for estates of various sizes. For landowners who owned several estates, a bailiff, or steward, supervised the various farms as well as the allocation of resources such as slaves. Different farms often specialized in different crops, resulting in more complexity. In the construction of large buildings and civil works projects, workers were organized in gangs that specialized in different tasks. All were under the direction of overseers, and they in turn were under the supervision of the master builder, who was a person of high prestige and importance in early societies. The Romans’ superb roads, bridges, and aqueducts are evidence of their skill in managing resources and labor.

The Industrial Revolution

The growth of larger towns, cities, and states caused additional demands for manufactured products. This was primarily because of four factors: the growth of wealth from trade and exploration; the larger markets represented by the population growth and its concentration in towns and cities; the introduction of new products by creative craftsmen in competition with each other; and the development of new technologies. These four elements eventually led to the development of the factory system for producing manufactured goods. As you may recall, factories were locations where labor and resources were brought together to allow more efficient manufacture of goods. Establishment of factories was based on the acquisition of land, labor, and capital by businessmen seeking to make money through capitalistic economic practices. Early factories were concentrated in the textile industries. In England, changes in banking practices made accumulation of wealth and its availability as capital more attractive to those willing to risk investment in large-scale manufacturing operations. The success of early factories was due to the division of labor into specialty areas, where individual laborers performed only one or two specific tasks, sometimes aided by mechanization. The new technology of steam-powered equipment and

Manufacturing Processes, Part 4 5 improved machine tools greatly increased the productivity of individual workers gathered in a factory environment, but even when new technology wasn’t used, manufacturing and assembly operations were greatly improved by labor specialization and assembly-line techniques. Factories were physically laid out so that the work flow was logical and workers didn’t have to move to different areas. Where multiple products were made, either the workers dealt with minor product variations or else additional lines were added.

Mass-Production Methods

You’ll recall that many of technology’s advances were driven by the urge to achieve military superiority, and that many of the techniques for producing high-quality goods rapidly were developed for strategic reasons. In fact, armies were usually the greatest consumers of many types of manufactured goods. However, as commercial economic markets became available with growing populations and rising middle classes, factory methods were used to make products intended for everyday use by consumers, a classification of the portion of a population that had disposable income—money over and above minimal living expenses—that allowed them to buy labor-saving devices or spend for recreational purposes. Mass-production techniques were greatly assisted by the development of relatively sophisticated machine tools and the standardization of interchangeable parts. Standard dimensions for fasteners and other common parts improved the quality and reliability of products, and advances in extraction and metallurgy techniques improved both the products and the machines that made them. Assembly-line techniques have often been credited to automaker Henry Ford, but in fact they were used earlier in meat-packing factories in Cincinnati and Chicago. By adopting similar methods, in particular the practice of moving the work to the worker, Ford was able to reduce the number of man- hours needed to make an automobile to under 11/2 hours. This reduces manufacturing costs and increased market potential by lowering prices to consumers. His competitors were forced to do the same in short order, and mass

6 Manufacturing Processes, Part 4 production and assembly-line techniques were soon common- place in manufacturing businesses throughout the country. These manufacturing concerns all had several factors in common: manufacturing tasks were finely divided, and most operations required low skill; a larger supervisory structure was required as the factories grew in size; and more engineers, accountants, and human resources people were required to manage the large number of workers. With more specialized people needed to run more complex organizations, factories were internally organized to group personnel with similar functions into departments supervised by managers. The specialization of functions extended to other departments such as accounting, marketing and sales, as well as engineering. Figure 2 shows the management structure of a typical manufacturing business. Note the specialization of each department and the way each group reports to the chief executive officer (CEO). Also note that the plant manager—the senior person that production personnel would report to—is not the person in charge of the business, but is instead one of several executive managers. In fact, in some businesses the CEO, the chief financial officer, and other senior managers may not even be physically located at the factory site. Workers on the production lines would report to a department supervisor (perhaps a shift supervisor if the factory runs 24-hour days), and the department supervisors would in turn report to the production supervisor (Figure 3).

Manufacturing Processes, Part 4 7 Chief Executive Officer (CEO)

Sales and Plant Manager Chief Financial Research and Marketing Manager Officer (CFO) Development

Production Sales Force Accounting Development Supervisor Engineers

Materials Customer CAD Manager Service Human Designers Resource Manager

Test Production Engineering Engineering Managers Quality Lab Assurance Manager

Information Technology

Facilities Manager

Manufacturing Engineering Services

FIGURE 2—The management functions of a factory are divided into specialized areas. The people on the executive management team report directly to the CEO.

8 Manufacturing Processes, Part 4 ProductionProduction Supervisor

OtherOther Departments Departments OtherOther Departments Departments

Department ShiftShift DepartmentDepartment Shift Shift Department Shift Shift Supervisor (2nd(2nd Shift) Shift) SupervisorSupervisor (1st(1st Shift) SupervisorSupervisor (3rd (3rd Shift) Shift)

Worker Worker Worker

FIGURE 3—Within the production areas, individual workers report to a supervisor, who in turn, reports to a production supervisor. Technical problems are first reported to the supervisor, who determines the proper approach to find a solution, perhaps involving people from other departments as necessary.

While Ford and others’ assembly-line techniques were huge successes compared to prior practices, their success focused more attention on the efficiency of the individual worker. The push to be even more efficient and competitive gave rise to a new field of study, industrial engineering, sometimes called operations research. A scientific approach to analysis of manufacturing tasks had already been done by

Manufacturing Processes, Part 4 9 Frederick Taylor, who recommended eliminating unnecessary motions on the part of the workers, and dividing labor into specialties. Taylor spent a lot of time measuring worker performance, analyzing tasks for essential components, and eliminating unnecessary steps, thus earning his general techniques the name of scientific management. In 1909, researchers Frank and Lillian Gilbreth also studied the specific, detailed motions that workers made to assemble products, giving rise to the method of motion studies in industrial engineering. Motion studies measure the amount of time workers actually spend on the task, as opposed to setup, or gathering material and tools. Industrial engineering later came to include virtually all aspects of manufacturing, including plant layout, control of materials, division of tasks, and even product design. Industrial engineers are often involved in design for assembly, or DFA, when new products are conceived and brought to a manufacturing environment (Table 1).

Table 1 DESIGNING MANUFACTURED PRODUCTS FOR EASE OF ASSEMBLY • Identify critical part characteristics such as surface finish, tolerances, and strength. • Identify manufacturing factors to achieve critical part characteristics.

• Determine process capability to achieve critical part characteristics.

• Avoid tight tolerances.

• Minimize the number of machined surfaces.

• Design for easy inspection.

• Use standard manufacturing processes where possible.

• Minimize the number of reorientations during manufacture.

• Use generous radii and fillets on parts. • Combine or eliminate individual part features to minimize the number of parts per assembly. • Design parts for easy jigging or fixturing.

10 Manufacturing Processes, Part 4 Factors of Production

As more people are involved in the production of a product and manufacturing tasks are divided into specialized subtasks performed by low-skill workers, some type of management hierarchy must be in place to ensure they all meet their responsibilities for efficient production. In most manufacturing operations there’s a position called production manager whose responsibility is to monitor and supervise critical production factors. These factors, shown in Figure 4, are the “five M’s.” You’ve already encountered four of them: men (including women), machines, materials, and methods. A fifth factor, money, is added to these familiar factors of production.

Machines Materials Methods (Processes)

Products

Customer Manufacturing Outputs Requirements System Inputs

Waste

Men Capital (People)

FIGURE 4—Manufacturing uses the factors of production organized by managers to produce finished goods from raw materials in processes that add value to the product at each step of the progression.

Men. The production manager (PM) manages the people involved in the manufacturing process. He or she ensures workers maintain an acceptable work ethic, work well with other people, and have or acquire the necessary skills. The PM is often responsible for writing job descriptions and monitoring satisfactory performance of workers, and arranging training when necessary.

Manufacturing Processes, Part 4 11 Machines. The PM selects the correct machines for each step, and ensures the machine is properly set up and well maintained. The PM generates and implements maintenance schedules to make sure machines are in good working condition. Materials. The PM arranges the flow of raw materials and work-in-progress (WIP) to the proper machines at the right times. Information about the flow of materials and product is maintained by the PM and reported to the appropriate senior management. Methods. The PM is responsible for selecting appropriate manufacturing processes and technology and for arranging the effective use of the machines with proper scheduling. Money. The PM’s concern with money is mostly related to inventories, which can represent a significant portion of a company’s assets. Inventory control involves monitoring finished goods, work-in-progress, raw materials, component parts, packaging materials, supplies, and even capital equipment used for production. In general, the production manager must ensure a smooth flow of materials and work so that the company’s production goals are met at the highest quality level possible. The PM monitors the progress of production against a plan, making sure that the processes are optimized or making improvements where possible. As a manufacturing technician, the most important thing for you to remember about the factors of production is that all of the recent manufacturing techniques developed aim to control these factors in a way meant to minimize costs and increase quality and production rates. When you hear about manufacturing methods such as kanban, just-in-time, or lean manufacturing (each of which is discussed in this study unit) you need to ask yourself how this method works with each of the five factors. You may find that in the end, there are few differences in the way each of the methods works compared to others.

12 Manufacturing Processes, Part 4 Self-Check 1

At the end of each section of Manufacturing Processes, Part 4, you’ll be asked to pause and check your understanding of what you’ve just read by completing a “Self-Check” exercise. Answering these questions will help you review what you’ve studied so far. Please complete Self-Check 1 now.

1. The formal list of the responsibilities and qualifications for a manufacturing job is called a ______.

2. Study of manufacturing processes eventually evolved into a formal discipline called ______.

3. Before large-scale manufacturing production in factories, people just learning a trade or skill were known as ______, and were taught by recognized experts in the trade.

4. A location where labor and resources were brought together for more efficient manufacture of goods is called a ______.

5. The appearance of consumers with ______led to increased use of factories to produce goods for popular consumption.

6. The development of ______for dimensions and measurement units greatly aided the evolution of mass production techniques.

7. Taylor’s observation and analysis of worker tasks, and his recommendations for improvements, came to be known as ______.

8. A ______is the person in a factory whose responsibility it is to monitor and supervise critical production factors.

Check your answers with those on page 67.

Manufacturing Processes, Part 4 13 MANUFACTURING FORMATS

As more advanced manufacturing facilities developed during and after the Industrial Revolution, different physical layouts as well as work organization models appeared. Each type of layout and organization has advantages and disadvantages, and astute production managers and business owners are quick to adopt elements that suit their particular industry and products. Also, different product types and production volumes often dictate within fairly tight constraints how the products are made. A manufacturing shop that specializes in prototypes will look very different from a high-volume bicycle shop, for example. While the system of classification described here is tidy, you’ll find that there’s much overlap in actual practice.

Types of Manufacturing Production

Manufacturing production types can be broadly classified into four different categories that depend for the most part on the production volumes and types of products: job shop, batch manufacturing, mass production, and continuous production. Production planning and control is quite different for each type, but all have benefited from the efforts of such industrial engineering pioneers as Taylor and the Gilbreths. Figure 5 shows a rough breakdown of production types based on production quantities.

Job Shop Production

Job shop production can occur in very small and very large manufacturing businesses, as the products of this type of production format range from simple, one-of-a-kind items like replacement parts for antiques, to things as complex as components used in the construction of a ship or a bridge. These products are often made to order on a custom, or at least an infrequent, basis. Small job shops often supply parts to larger job shops, and maintain adequate production volumes only by establishing a reputation among these larger entities for supplying high-quality parts in a timely fashion.

14 Manufacturing Processes, Part 4 Increasing Increasing Quantity Variety Continuous Production

Process Manufacturing

Mass Production

Batch Production

Discrete-Part Production

Job-Shop Production

1 10 2500 100,000

Production Volume

FIGURE 5—Although these classifications overlap considerably, different manufacturing formats lend themselves to different types of production volumes. In general, high production volumes are often achieved by sacrificing flexibility.

Some job shops acquire a reputation for working with specialty materials, such as refractory metals like tungsten and molybdenum, or hazardous materials such as beryllium. Working with these specialized materials requires special techniques and equipment. In general, successful job shops require a wide range of machines and equipment to deal with unanticipated production demands. Because they need to be flexible, job shops normally carry high levels of raw material inventory and supplies. They also require highly skilled personnel who can adapt to nonrepetitive manufacturing tasks and projects. For example, sales and engineering personnel tend to be adaptable and cross-trained in several disciplines, especially for smaller job shops, which seldom have the resources to hire specialized engineers or technicians. Many

Manufacturing Processes, Part 4 15 projects are prototypes or feasibility trials and may never have been done before, which adds to the experience and expertise needed by job shop staff.

Batch Production

Batch production is the manufacture of similar products, such as bicycles, electric motors, or computers, to meet a continuing market demand. These types of products aren’t usually made on an as-needed basis, but they’re produced in quantities based on projected demands and stored until they’re delivered to the end user. Storage and packing are therefore important considerations in planning and control of batch manufacturing operations. Batch sizes can vary from small to large, and the work-in-progress is always large. Batch production usually uses general-purpose machine tools, and production planning must be as efficient as possible to minimize the number of machine setups and movements of material to different workstations. An advantage of batch production is the ability to monitor time and dates of manufacture of critical components. Tracking batches and lots by date and serial numbers allows manufacturers to recall and repair products that fail in service. Car manufacturers have long been able to recall certain vehicles for repair or replacement of critical components such as gas tanks or alternators, and toy manufacturers have done the same for toys that break in ways dangerous to small children.

Mass Production

Mass production is the manufacture of very large numbers of identical components or assemblies that are needed on a continuous basis, such as cars, appliances, or even machinery. Complex products such as cars may have multiple mass-production sites producing component parts in parallel, and moving them to an assembly location to make the finished product. Raw materials are fed into these systems at preplanned rates to ensure continuous production, while minimizing work-in-progress as much as possible.

16 Manufacturing Processes, Part 4 Failure of any part of a mass-production system can have severe consequences, so maintaining some inventory is necessary. Tasks in a mass-production facility are divided into simple, easy-to-do operations, assisted by sophisticated machines and tools. This has the advantage of requiring only low- to medium-skilled help, and promoting high levels of product consistency and uniformity: the machines are responsible for maintaining the product quality, not their operators. The disadvantage of this labor division is that it’s very difficult to change machines and equipment should the system need to be modified, and highly skilled labor is needed to maintain, troubleshoot, and program the machines. Production planning must be nearly perfect because it’s extremely difficult to change the system, although the use of modern computer- controlled machine tools helps somewhat. Productivity increases for mass-production facilities in the future are likely to come from more use of programmable machines that can do multiple tasks without human intervention.

Continuous Production

Continuous production is the manufacture of products that are made using an ongoing process such as distillation or chemical processing. It’s mostly found in chemical and food- processing industries, although the production of wire could be classified as a mostly continuous process. The production of gasoline is a continuous process, using heat to evaporate crude oil fed to the evaporator, and then collecting gases and liquids that result from this evaporation. Figure 6 shows the general relationship between expected product quantities and flexibility in design for the formats we’ve discussed. Table 2 summarizes and compares some of the critical characteristics of different manufacturing formats.

Manufacturing Processes, Part 4 17 Dedicated

Process Manufacturing

Mass Production

Batch Production

Job-Shop Production

Custom Designs Standard Designs Flexible

1 10 2500 100,000

Production Volume

FIGURE 6—Increasing production quantities usually requires efficient dedicated equipment to achieve high throughputs (or cycle times), and isn’t suited to variations or options. Smaller quantities can be customized at many points during the manufacturing process.

18 Manufacturing Processes, Part 4 Table 2 MANUFACTURING FORMAT COMPARISONS Terms of CONTINUOUS JOB SHOP ASSEMBLY LINE Comparison PROCESS Typical Products: Furniture/Engineering Automobile/Electronics Beer/Cement

Capital investment Low Medium High

Overheads Low Medium High Direct workforce: Skilled Low Semiskilled Skills Direct workforce: High Medium Low Numbers Materials to labor 60:40 70:30 90:10 ratio Nature of order Make-to-order Make-to-stock Make-to-stock

Forecast stock Forecast stock Scheduling Backward replenishment replenishment

Product variety High Medium Low

Product changes Frequent Routine Occasional

Components/Finished Raw materials / Inventory location Work in progress goods Finished goods What do people buy Competence Quality product Consistent products from us? Quality (functionality/ Qualifiers Quality (reliability) Quality (conformance) competence) Winners Lead time Price / Brand Price

Low priorities Cost Lead time Flexibility

Major waste areas Inventory/Scrap Downtime / Rework Downtime / Yields Equipment Layout

Identifying the correct layout of manufacturing facilities often requires considering some specific aspects of the products and processes that are in use or are being evaluated. In an existing operation, the location of new equipment is unfortu- nately often determined by what free space is available rather than considerations of where it will be the most efficient. In general, a formal process of analysis and decision making

Manufacturing Processes, Part 4 19 should be done to determine the most appropriate factory and equipment layout. A recommended process would be as follows: Step 1. Identify objectives: What should the new or changed layout accomplish? How can you quantify or measure those objectives? How will new technology or techniques improve capabilities, products, or efficiencies? Step 2. Identify product families: Product families are products that are basically the same and are manufactured by similar processes and equipment. Product families usually share much of the same equipment. Step 3. Map the processes: A process flow chart should be generated for each product or product family. Process flow charts are diagrams showing each work center, the sequence of operations, material flow, and information reporting requirements. Step 4. Process improvements: New equipment and technology should be implemented in a way that takes advantage of new features and capabilities. This is an iterative process, occurring on a regular basis. Managers must constantly analyze the how and why of existing processes as new technologies become available and others become less efficient. Simply automating an existing process may not take full advantage of new technologies, and may actually be counter- productive for the most effective manufacturing processes. Step 5. Improve housecleaning: Eliminate clutter and unneed- ed items; organize and identify materials and equipment; clean work areas and install signage; train employees in housecleaning procedures. This so-called 5S method stands for Sort, Set in Order, Shine, Standardize, and Sustain, a workplace checklist for daily improvement. Step 6. Reduce setup times: Define the steps for each process and machine; identify the steps that must be done while the machine is stopped and those that can be done when it’s running; duplicate tooling and fixtures where possible to eliminate waiting; try to eliminate or reduce unnecessary steps.

20 Manufacturing Processes, Part 4 Step 7. Analyze constraints: Identify internal and external process constraints: material limitations, inadequate processes, worker skills and knowledge, and available space. Step 8. Process simulation: Sophisticated computer software can simulate manufacturing processes and evaluate alternatives. Step 9. Analyze relationships: Make a diagram that lists the work centers in the manufacturing process, and create a matrix that identifies those areas that need to be close together. List the work areas on the horizontal and vertical axes. At the intersections of the rows and columns, rank the importance of having the areas physically located close together. Some reasons why areas may need to be close: shared supervision, shared personnel or equipment, ease of maintenance or service, communications requirements, and safety requirements. Step 10. Develop the layout: Diagram the positioning of work centers, offices, storage areas, rest areas, and any other important functional areas. Try to optimize the important relationships established above. An organized approach to work area layout will lead to increased efficiencies, and may result in combining the types of layouts discussed in the next section. The physical arrangement of the capital equipment and machine tools necessary to manufacture a line of products can greatly influence the efficiency of the manufacturing process and the fundamental cost of production. Industrial engineers will study many variations of machine placement for current and projected production quantities before a plant design is finalized. Once an arrangement has been implemented it’s very difficult to change without expensive modifications. Over the years, four basic equipment layouts have used regularly used: • Functional layout

• Cellular, or group, layout

• Flow line layout

• Build-in-place

Manufacturing Processes, Part 4 21 Functional Layout

This type of equipment arrangement is probably the oldest as well as one of the most common, especially for job shop and batch production. Figure 7 shows a typical layout of machine tools arranged by type, and an example of work flow for a batch of parts. An advantage of this type of arrangement is that supervision of each area can be specialized; that is, the supervisor in charge of the milling machines can be an expert in milling processes, milling machine setup, and perhaps even programming of CNC (computer numerical control) mills.

Turning Drilling Grinding Department Department Department

Indicates Components’ Batch of Indicates Actual Path Components Work Location

Milling Department

Inspection Department

FIGURE 7—A functional layout with similar machines located in the same area is efficient for smaller job shops and batch production methods. For larger quantities, material and personnel travel time limit efficiency in this type of layout.

Functional layout is very flexible and is therefore suited for prototyping and one-offs, job production, or small batch production. Throughput time (sometimes called cycle time), the time it takes from start to finish of a manufacturing operation, can be quite high because of the amount of handling required to move parts from machine to machine. Setup time can be substantial because of the different requirements of each batch of parts. For batch production, there’s usually a large amount of work-in-progress, making inventory costs high.

22 Manufacturing Processes, Part 4 Cellular Layout

As the capabilities and sophistication of CNC machines has increased, cellular layouts have become more popular. Figure 8 shows an example of a simple manufacturing shop with a cellular layout containing several machining cells. The key feature of a cellular layout is that all of the machines necessary to make a specific component, or family of components, are located in one area, so material handling is much simpler. Depending on the degree of automation within the cell, material handling can be done with industrial robots, minimizing the need for human labor within the operation.

Grinder Mill Planer Lathe Mill Drill Lathes Grinder Drills Lathe Saw Cell C Honing Machine Mill Cell D

Cell A

Assembly Department Coordinate Measuring CNC Machining Center Parts-Cleaning Machine

Cell B

Inspection Department

FIGURE 8—Cellular layouts tend to improve quality as well as production volumes due to the close proximity of the machines, the operators, and the cell supervisors. Material travel time between manufacturing steps is significantly reduced.

Manufacturing Processes, Part 4 23 Cellular layouts require high product volumes to justify their costs, and automated handling and assembly can be very inflexible if they must be adapted to meet product variations. However, with more sophisticated communication and control, machines can be made to work with a range of variations or options, allowing some customization within high-volume manufacturing operations. Figure 9 shows a sophisticated robot of the type that’s now being used to load and unload machining centers.

FIGURE 9—Robots work faster and more consistently than human operators.

For businesses where these layouts are efficient, there are many advantages to a cellular layout: • Cellular layouts promote team spirit, and members of a group are more likely to pull together to make their particular operations successful.

24 Manufacturing Processes, Part 4 • Members of the group are usually capable of performing all the required functions within the cell, which allows for job rotation, minimizes boredom, and ensures contin- ued production even if one of the members is absent.

• Supervision of cells is tighter and administrative paperwork is minimized. The supervisor can make sure that all parts produced are at the quality level desired.

• Work-in-progress and inventories are greatly reduced because of the cell specialization and work flow.

A major disadvantage to cellular layout, other than its cost, is that each cell is set up to produce one particular part or assembly, and while programming and sophisticated automation can increase the number of variables the machines can deal with, significant product changes would require redesigning and reequipping the cell. Also, flexibility between cells often isn’t good, and maximum machine utilization isn’t guaranteed, since the usage of a machine in each cell is determined only by the tasks assigned to it in that cell. A lathe in one cell may be used only a few hours a day, while a similar lathe in another cell is in constant use.

Flow Line Layout

Flow line layout is most similar to the mass-production lines found in automobile factories like the ones Henry Ford built. When a product has a continuous demand, as is the case for trucks and automobiles, flow line layout offers the highest production rates of any factory process. A specially designed arrangement of equipment and machines, called a transfer line, can perform a set of grouped tasks, with the output product sent as a finished good or transferred to another flow line to incorporate into a more complex product. Figure 10 shows an example of a transfer line that can be set up in two configurations. A flow line can be completely linear, or it can be made U-shaped, reducing the amount of floor area required. In a U-shape, one operator can perform multiple tasks on different sides of the U.

Manufacturing Processes, Part 4 25 Raw Material Input

Drilling Final Sawing Turning Boring Milling and Grinding Finishing Inspection Tapping

Component Output

Linear Layout

Raw Material Sawing Turning Boring Milling Input

Component Final Drilling Inspection Finishing Grinding andand Output TappingTapping

U-Shaped Layout

FIGURE 10—Flow line layouts use transfer lines to move materials between manufacturing operations. Alternatively shaped layouts can be used to save space and labor time.

A disadvantage of flow lines is that if one operation breaks down, the whole line stops; flow lines therefore often have areas of buffer stock placed at likely locations to keep the line operat- ing should something go wrong at one of the stations. This obviously increases the work-in-progress inventory and associated costs. Flow lines aren’t usually used where a lot of consumer choice is required, since a flow line layout can’t easily deal with product variations. A flow line is expensive to set up, so it wouldn’t be used for products whose life cycle is short. Cars, for example, have a full model year of production and changes to next year’s model are often minimal. On the other hand, cell phones, clothes, and toys change continuously, with styles changing frequently due to customer preferences.

26 Manufacturing Processes, Part 4 As we’ve said, some flexibility can be built into flow lines with the use of programmable (and reprogrammable) robotic devices that can be adapted to product ariations. This decreases the time to reconfigure the line to produce another product.

Build-in-Place

Some manufactured products are so complex or so big that it isn’t feasible to move the product through a line, and the labor and materials are brought to a single site. This is the case for products such as ships, bridges, or spacecraft. Houses are another type of product built on site; however, manufactured housing is done in factories set up with flow lines as discussed previously.

Manufacturing Processes, Part 4 27 Self-Check 2

Complete the following statements.

1. The main factor that determines the manufacturing format is ______.

2. The most likely manufacturing format for producing product prototypes would be ______.

3. Comparing the people employed in job shops and mass production lines, those in ______manufacturing are more likely to have multiple skills, making them versatile.

4. Moderate production volumes produced in ______manufacturing facilities usually require general-purpose machine tools.

5. Tasks in a ______facility are divided into simple, easy-to-do operations, assisted by sophisticated machines and tools.

6. Gasoline and chemicals are made using ______manufacturing formats.

7. The manufacturing format that has the largest capital investment costs is ______

8. Production labor in ______manufacturing formats is likely to have the highest skills.

9. A checklist tool for workplace housecleaning is known as the ______tool, and is used to improve the appearance and function of the work areas.

10. Placing machine tools with similar functions in the same location in the factory is called a ______layout.

11. ______is the total time it takes to manufacture a product in a factory.

12. Grouping all of the machines necessary to make a single assembly or part is called ______layout.

13. ______layout can be linear or U-shaped to save shop floor space.

14. Construction of the space shuttle Atlantis was probably done with a ______manufacturing format.

Check your answers with those on page 67.

28 Manufacturing Processes, Part 4 AUTOMATION AND MECHANIZATION

You may find it hard to believe, but the number of manufacturing jobs has been decreasing steadily since the latter part of the twentieth century, even though the number and variety of products has increased. That’s because fewer workers are producing more goods of higher quality than ever before. The major reason for this increase in productivity has been the increased use of mechanization and automation. As automated processes became more common, manufacturing wages have increased and the number of hours worked per standard workweek has decreased from 60 to 40. Many people think mechanization and automation are the same, but they aren’t. Mechanization is the replacement of a human action by a mechanism. Automation also means replacing human action by a machine, but with the added ability to control the action remotely. The word “automation” was first used in the automobile industry in the late 1940s to describe the increased use of automatic devices with controls in the car assembly lines. Automated machines are usually controlled by a closed-loop system, where the process is measured and compared with the desired value, and adjustments made to the system based on the difference. Figure 11 shows a simplified diagram of a closed-loop control system. You can further classify automation by noting whether the machine is designed with fixed functions or whether it’s programmable. Fixed-automation machines are designed for specific purposes, often with mechanical devices such as cams, levers, or gears. Making fixed-automation equipment perform other tasks requires extensive and expensive modifications. By contrast, programmable automation can change its function and required tasks by changing the computer program that controls the equipment. Sensors provide feedback to a computer about the position, velocity, acceleration, and applied forces of the actuators that move machine tool cutters, welding heads, or robotic arms. Some “smart” actuators have embedded sensors that constantly send information about machine activities back to a controller. Sometimes there’s even a “supervisory” computer that monitors and

Manufacturing Processes, Part 4 29 Control Signal Error Signal

Input + Process (Desired · Controller Output (Actuators, Machines) Condition) _ (Actual Condition)

Summing Amplifier

Sensing Elements

Feedback Signal

Measures Positon, Velocity, Temperatures, Pressure, Part Count, etc.

FIGURE 11—A closed feedback loop enables automated machines to be precisely controlled by humans or by programmed computers. Sensing elements measure the condition of the output and feed it back to a summing amplifier that compares the actual output with what’s desired. An error signal is fed to an amplifier, which generates a control signal used to manipulate the actuators, machines, or other process machines.

controls many other computers in a production line. Use of programmable automation such as the PLC controller shown in Figure 12 can enhance the flexibility of a manufacturing system by allowing machines to deal with desired variations on every piece that moves through the production line.

Evaluating Automation

Automated equipment can benefit many types of manufacturing formats, but whether it will be profitable depends on a number of factors: • Assembly costs

• Production rates and quantities

• Availability of skilled and unskilled labor

• Life cycle of the product

• Cost of automated equipment and the extent of automation desired

30 Manufacturing Processes, Part 4 FIGURE 12—Programmable logic controls (PLCs) can control machines as well as supervise other computers, allowing easy changes in sequences, robot or machine motions, or the timing of different processes.

The many advantages of automation include labor cost savings, increased production rates, better product quality through consistency, and safe operation in hazardous or toxic environments. Disadvantages of automated systems include their cost, but also less flexibility in many cases, and more susceptibility to interruption or damage from faulty parts. Parts fed into automated equipment must be of consistent quality and in the correct “presentation” to avoid line breakdowns from defects that a human operator could easily remove or fix. Surveys indicate that the greatest cause of automated-machine stoppage is faulty or out-of-spec parts fed to the machine.

Manufacturing Processes, Part 4 31 Effective use of labor resources is a key factor in manufacturing profitability. Eliminating expensive, skilled labor performing routine tasks is one of the ways automation has the potential of improving the efficiency of production operations. Here’s a general analysis of the cost effectiveness of an automated system compared to a manual one. This analysis takes into account the cost per unit for each: • Automated unit cost = (cost of part transfer systems + cost of feeding and placement devices + machine costs) Ϭ production quantity

• Manual unit cost = [(number of operators ϫ average wage ϫ time to make production quantity) + (cost of equipment for manual manufacture)] Ϭ production quantity

Comparing these values will yield insight as to whether or not automated systems can successfully improve profitability. This economic analysis is very rough, and many details and circumstances need to be added to the above general categories. Other circumstances may also affect decisions, such as the availability of skilled labor for equipment operation and technical support. Figure 13 shows the relative costs between machined parts for various types of machine tools compared to the production quantities needed.

Special-Purpose Automated Processes Manual Machine Tools

CNC Machine Tools General-Purpose Automated Processes Relative Machining Cost per Piece Flexible Manufacturing Systems 10 100 1000 10,000 100,000 1,000,000

Production Quantities

FIGURE 13—The production quantities required will have a significant effect on the cost of automation as well as the range of practical manufacturing formats.

32 Manufacturing Processes, Part 4 Automation will have a major impact on an existing workforce if it displaces many employees, resulting in unpredictable and hard-to-measure human-resource costs. Workers would be more socially isolated as well as being required to assume new and perhaps more mundane responsibilities. But labor costs may decrease significantly, production rates may greatly increase, and workers with greater technical skills must be hired to maintain, adjust, troubleshoot, program, and upgrade automatic equipment such as robotic welders (Figure 14).

FIGURE 14—Robot controls and programming require skilled technical people who understand both the process and the automation controls used to perform the work.

Manufacturing Processes, Part 4 33 In general, it’s not always the best policy to automate everything in a manufacturing operation. Automation should be used only when it makes economic sense. Automated systems lend themselves well to very large production rates while maintaining high and consistent product quality. As we’ve mentioned before, automated systems can work in toxic or dangerous environments where people shouldn’t. Parts produced by automated systems are high quality, and changes in a process can occur only with changes in the programming or adjustments of the machine controls. The lead times of every automated process can be precisely known, and the overall time to complete a product will be greatly decreased. These give the business the ability to “make-to-order” rather than maintain large inventories in anticipation of future orders. All of these effects are accompanied by a greatly increased capacity to monitor production functions using tracking information provided by the machines and the computers that control them. A final advantage of automated equipment is that some products such as turbine blades and electronic wafers are so complex that only precisely controlled machines are capable of making them.

Automation Strategies

Implementing automated factories is a capital-intensive task requiring large amounts of money and human resources, and the cost of the automation must be covered by the increased production and profit over a reasonable payback period. In considering where and how automated machinery could be used, the following questions could serve as a guideline: • Could multiple operations be performed on the same part by the same workstation? Could multiple operations be performed simultaneously, such as drilling multiple holes?

• Could several workstations be combined functionally into a work cell with the use of automatic handling equipment, allowing a continuous flow of production?

• Would a specially designed, fixed-purpose machine built to perform one or more operations with great efficiency be economically viable?

34 Manufacturing Processes, Part 4 • Could the machine or the workstation be made flexible, i.e., able to perform different but similar tasks to account for options or variations in manufacturing processes? Could the machine be reprogrammed quickly to handle different product lines with little setup or layout change?

• Would robotic handling devices reduce material-handling time, material movements, or setup times?

• Will the use of computer controls increase data collection capabilities and therefore decrease management response time to changing situations?

• Can common databases be developed in CAD and design software that can be used by all factory departments, such as planning, purchasing, production control, engineering, and sales?

Industrial Robots

In high-volume production environments, the use of robots for material handling and placement is often necessary because of the extremely repetitive motions required or the low cycle times needed for the equipment. In other applications, the robot is actually doing the work or holding the work tool, such as a welding or paint-sprayer head. Several different types of industrial robots are prevalent in manufacturing businesses. These include the continuous- path and the pick-and-place types. In general, robots are classified by the number of axes of available motion. Z Figure 15 shows the possible axes of movement, which are the three linear axes of Y length, width, and depth (X, Y, and Z); and rotation about these three axes, making a total of six possible movements. A robot’s range of motion is limited to one or more of A these six directions, with few robots capable B C X of moving in all six of them. The more movements possible, the more complex and costly the robot. Figure 16 shows a robot for a welder capable of several rotational FIGURE 15—Possible Axes of Motion

Manufacturing Processes, Part 4 35 FIGURE 16—This welding robot can perform complicated motions to produce rapid, consistent welds.

motions that can combine to give translation in the X, Y, or Z axes, even though there’s no direct movement of the machine in these axes. Pick-and-place robots have motions limited to movement between one fixed point and another, or a start and finish point. They can precisely “pick” a part or assembly at one location and “place” it at another; their motion isn’t controllable in between. Pick-and-place robots usually have only two to four axes of motion, and are usually driven by hydraulic or pneumatic cylinders. Because of their simplicity, pick-and-place robots are usually the least expensive type. Figure 17 shows an

36 Manufacturing Processes, Part 4 CNC Milling Machine Pick-and-Place Robot

Conveyor Line Milled Parts

Parts Ready for Milling

FIGURE 17—Pick-and-place robots load and unload machine tools quickly and accurately. This one has two axes of motion, one linear and one rotational. example of a pick-and-place robot used to take parts from a moving conveyor line and move them to a work-station for a machining operation. Continuous-path robots often can move in multiple axes. Their heads move in precise three-dimensional paths, as might be needed for painting or welding. They have position and velocity control (second-order feedback loops) and are often controlled by electrical actuators, which can be more easily controlled by computers. Some types of continuous-path robot can be programmed for motion by “teaching” it the path: a human operator will move the head through the desired motion, and the resulting path is digitized and stored in the computer memory. Mathematically, the computer will take a series of coordinate points and construct a path of motion that’s placed in memory. The speed of the head during each portion of the path can also be varied depending on requirements. Figure 18 shows a six-axis robot that can be

Manufacturing Processes, Part 4 37 FIGURE 18—This robot can be used for many Waist Rotation types of applications because of the great Shoulder Rotation flexibility in its possible motion. The working head isn’t shown, but it could be a gripper, welding head, or paint gun. Elbow Rotation

Wrist Rotation

Wrist Bend Gripper Mounts Here

Rotation

used to load and unload a machining center. Figures 19 and 20 show different head styles used for specific tasks, such as welding, painting, or securing parts to another location. Figure 21 shows other common forms of industrial robots.

38 Manufacturing Processes, Part 4 FIGURE 19—This robot head is a gripper with multiple “fingers” that allow it to securely hold parts as they’re transferred to a machining center.

Manufacturing Processes, Part 4 39 FIGURE 20—This robot has a welding head for automated TIG (tungsten inert gas) welds.

Pick-and-Place Rotary Robot Universal Robot

Part Trays

FIGURE 21—Robots can be made in many different sizes and configurations to do specific Workchanger Robot tasks. Unlike humans, robots aren’t confined to Gantry Robot just one shape.

40 Manufacturing Processes, Part 4 Although not usually thought of as simple robots, material- handling systems often perform similar motions. Many work- transfer stations prepare parts or assemblies to be handled by robots prior to the manufacturing operation, as shown in Figure 22. For example, a hopper may contain a quantity of small parts that are oriented and fed by a parts feeder to a rotary indexed transfer table. The robot will pick these parts off and place them onto the table for the next operation. Transfer stations can also have many different configurations, and they’re particularly useful for assembly operations where human operators may take the parts off the line for assembly into the product. Figure 23 shows three common types of transfer stations: rotary, rectangular (or U-shaped), and linear.

FIGURE 22—These robots are an important part of this transfer station, removing parts from trays to transfer them to a machining-center robot for a milling operation.

Manufacturing Processes, Part 4 41 FIGURE 23—Often not as Parts Feeder sophisticated as robots, transfer stations perform many of the same functions, and they’re Workhead particularly useful for Parts Carriers moving small parts or assemblies.

Indexing Table

Rotary Transfer (A)

Parts Feeders

Completed Assembly Workhead

Empty Work Carrier Parts Carriers

Base Placed in Position

U-Shaped Transfer (B)

Parts Feeders

Workheads

Part Carrier

Partial Assembly Moves to Next Station

Buffer Stock

In-Line Transfer (C)

42 Manufacturing Processes, Part 4 There are five main considerations in choosing a robot for an automation application: • Size—Not just the physical size and footprint of the robot itself, but also the maximum weight it can lift at the most extended position. Some modern robots can lift and manipulate more than 1200 pounds. Figure 24 shows a robot capable of lifting moderate to heavy loads.

• Reach—The maximum distance that mechanism can extend and the overall envelope of the possible paths the working head can traverse.

FIGURE 24—This robot has a long reach that allows it to move large distances. Counterweighting allows it to lift and manipulate heavy loads.

Manufacturing Processes, Part 4 43 • Speed—The maximum velocity with which the working head can move as well as maximum acceleration rates. This relates closely to the size of the robot, in that the greater the mass at the moving head, the greater the force that must be applied to start the head moving or to change its direction quickly. Modern robots can have more than 20 feet per minute of precisely controlled head speed for applications such as painting, gluing, or welding.

• Number of axes of movement—This will depend on the type of robot and the complexity of the tasks it must perform.

• Power source—Some robots require electric, pneumatic, or hydraulic power, or combinations of these. Power sources available in the factory may limit the selection of types or vendors.

In selecting robotic systems, the auxiliary equipment and tools must be considered in the final cost analysis. These could include pallets, conveyor lines, hand tools, pallet equipment, and software options. Calculation of the final costs can be compared to the possible savings achieved over the equivalent nonautomated processes used to produce the same production volumes.

44 Manufacturing Processes, Part 4 Self-Check 3

Complete the following statements.

1. One of the biggest factors in reducing the workweek in the early part of the twentieth century was the use of ______.

2. A control system that senses the output of a system and uses it to adjust the input is called a ______feedback system.

3. A type of automation usually done with gears, cams, or levers is called ______automation.

4. ______can enhance the flexibility of a manufacturing system by allowing machines to deal with desired variations on every piece that moves through the production line.

5. Automated production systems lend themselves to ______production rates and ______environments where people can’t work.

6. The decision to buy automated equipment is determined in large part by the ______period for capital invested in the equipment.

7. Robots can move in ______possible axes of movement.

8. Movement of parts from a conveyor line to a machining center and then replacing them on the conveyer is usually done by a ______robot.

Check your answers with those on page 68.

Manufacturing Processes, Part 4 45 MANUFACTURING MANAGEMENT SYSTEMS

You’ve learned that jobs in manufacturing are decreasing even though manufacturing productivity has increased. The main reason for this has been the pressure from more and more competitive industries and the use of advanced technologies to improve the entire product development cycle, from conception to delivery to the customer. Remember, manufacturing is the process of taking raw materials and adding value through inputs of other resources such as labor, capital equipment, and land, and then making a product available to the customer. Customers’ desires drive the market, and manufacturing responds to the product demand shown by their willingness to pay a given price for a product. Manufacturers must respond to the market and compete with other businesses that offer the same or similar products. To maximize efficiency, and therefore profits, manufacturing managers and theorists have looked at every phase of the product cycle to seek competitive advantages. Among the many buzzwords related to manufacturing systems, the central theme is the control of the manufacturing environment to maximize efficiency, lower costs, and increase profits. Two management systems that you’ll hear about are “just-in-time” and “lean manufacturing.” Just-in-time systems began several decades ago in the mid-1970s; lean manufacturing evolved in the 1990s as a response to the intense pressure for profitability in a more global economy. It’s important for you to recognize and understand these management systems because you’ll probably be working in an environment using one or more of these techniques. Proper implementation of these systems involves all employees, so you’ll be called on to contribute to improving efficiency to the best of your ability. You’ll also undoubtedly be involved in some type of quality assurance system that controls and manages processes and procedures that affect the quality of the parts and products.

46 Manufacturing Processes, Part 4 Just-in-Time (JIT) Manufacturing

The concept of just-in-time (JIT) manufacturing was developed by Taiichi Ohno, a Toyota production manager. He stressed the delivery of the proper amount of parts or materials, just in time for their use, and only as they’re needed. The JIT process resulted in major cost savings because it eliminated excess work-in-progress inventory, which can be enormous in large manufacturing businesses. Ohno went from assembly shop supervisor to vice president of the Toyota Motor Corporation in 1975 and helped it become the one of the largest auto manufacturers in the world, challenging (and in many markets surpassing) General Motors and Ford. Implementing JIT suddenly made cash available due to inventory reductions; factory response time improved significantly; and many products could be built to order, ensuring they would be sold rather than remaining in inventory. The successful application of JIT involves constant control of quality at every operation, since faulty parts leave production lines stalled from lack of parts. JIT also requires close attention to supplier quality issues and constant communication with vendors and customers to ensure precise coordination of requirements and deliveries. Today, the term supply-chain management refers to the effort to control the flow of materials all the way from the customer’s order to the raw material supplier. Modern communication methods using the Internet have made great strides possible. You’ll hear the term eManufacturing to describe the use of the Internet and computers to control manufacturing operations. In the ideal situation, a manufacturing firm can fill orders directly from customer information, and place orders for the raw materials or component parts based on supplier inventories that are communicated directly via the Internet. Firms like United Parcel Service (UPS) have built supply-chain management services to help small manufacturing businesses that don’t have the resources or expertise to develop good systems on their own.

Manufacturing Processes, Part 4 47 Another term closely associated with the JIT system is kanban. The Japanese word kanban means “card” and refers to the way the amount of work-in-progress (WIP) is controlled in a factory. Cards or tickets are attached to parts, batches, or pallets to monitor their location in the manufacturing process. When the supply of a part is depleted at a work center, its card is returned to the source to be refilled, but only when new parts are needed. The number of cards pres- ent control the total work-in-progress inventory, preventing excess parts from being produced by any work area. You may hear kanban described as a production control system, but its origin and implementation is very close to JIT. Figure 25 shows a segment of a manufacturing process that’s controlled by kanban. The goal of this system is to “pull” as few parts as possible with the kanban card, which will reduce the work-in-progress inventory level, and minimize the buffer stock needed.

Kanban Card Signal

(Needed Quantity)

Producing Process Consuming Process Completed Product

Buffer Stock

Maximum number of parts in buffer stock is determined by natural variations in the process.

FIGURE 25—Kanban Control for Just-in-Time Manufacturing

48 Manufacturing Processes, Part 4 Lean Manufacturing

Lean manufacturing, which grew out of the automotive industry, has been called a new model for manufacturing, and is based on the principle of eliminating any operation that doesn’t add value to the product. It can be applied to all aspects of purchase, design, development, and manufacture of any product. As a management philosophy, it focuses on reducing seven types of wastes: overproduction, waiting time, transportation, overprocessing, inventory, motion, and scrap. Manufacturing systems are typically either “push” or “pull” systems. In traditional “push” systems, customer orders trig- ger the inputs to a production line to begin to manufacture parts. But problems arise if an earlier operation is faster than a later one, excess inventory will pile up in front of the down- stream machine. Inventory is a form of waste—it takes up space, can be damaged or devalued, and uses up working capital. The ideal place for inventory is at the end of the production process, waiting to fill customer orders. But even that inventory should be only what’s necessary to cover confirmed orders. Implementing a “pull” production system that works from demand of products and parts from early parts of the production areas is a key feature of lean manufacturing. In a lean system, a customer order places a demand on the shipping department to ship orders, which places a demand on the warehouse to package and ship products, which places a demand on the assembly areas to finish assemble the product, which places demands on the flow lines or cellular areas to complete subcomponents, and so forth. The customer order causes demand ripples to flow through the factory from the output side to the input sides. People who work extensively with lean manufacturing concepts recognize that many costs become relatively fixed when a product is designed. This is because engineers tend to specify familiar, safe materials and processes rather than inexpensive, efficient ones. This tendency to use established and well-known materials and methods reduces the likelihood of project failure, but at the expense of innovation and

Manufacturing Processes, Part 4 49 lower costs. One way to avoid designed-in costs is to use concurrent engineering, a technique that puts product development in the hands of a development team, as opposed to a single design group. A concurrent engineering team will con- sist of members from the design, manufacturing, sales and marketing, purchasing, material control, and even shipping departments. As shown in Figure 26, serial product development activities are avoided and instead occur in parallel, with the next steps beginning before the last ones are completely finished. Successful organizations develop and review check- lists to review product designs to ensure that hidden costs don’t get built into a new product design.

Traditional Product Development

Design

Manufacturing Methodologies Setup Serial Activities Production

Time Parallel Activities Design

Manufacturing Shorter Methodologies Time-to-Market Setup

Production

Concurrent Engineering Product Development

FIGURE 26—Concurrent engineering enables many people to have inputs at all phases of product development, assuring that costs aren’t “designed in” and become unchangeable at later steps in the manufacturing process.

50 Manufacturing Processes, Part 4 Some key lean manufacturing principles that are implemented in real factory applications are as follows: • Perfect first-time quality—A concerted attempt to achieve zero defects in parts and assemblies, and to find and solve problems with existing processes early.

• Minimize waste—Eliminate all activities and materials that don’t add value, and increase the use of resources such as capital, people, and land.

• Continuous improvement—Reduce costs, improve quality, increase productivity and information sharing.

• Pull material flow—Products are “pulled” through a factory system from the customer end, not “pushed” from the production side of operations.

• Flexibility—Produce different mixes or a greater diversity of products quickly, without sacrificing efficiency at lower volumes of production.

• Supply-chain management—Develop and maintain long-term relationships with known, quality suppliers through risk sharing, cost sharing, and information sharing arrangements.

• Lean manufacturing processes—Whether they occur in design, manufacturing, or distribution—are all about get- ting the right things, to the right place, at the right time, in the right quantity while minimizing waste, being flexible, and responding quickly to changing conditions.

Quality Management and Quality Assurance Systems

In the end, manufacturing must always respond to market conditions and customer demands. In the increasingly global markets of the late twentieth and early twenty-first centuries and the competitive pricing of consumer and industrial products, product quality is critical. Customers look closely at product pricing and will choose value over simple price in many instances, evaluating both what the product costs and its apparent overall quality. Two products of comparable

Manufacturing Processes, Part 4 51 quality are chosen by price structure (or brand preference), but where quality clearly differs, price becomes less of a factor in a purchase decision. You’ll hear many different terms that refer to quality issues, and you need to know what they mean. Here are official definitions of quality system, quality control, and quality assurance published by ANSI/ASQC Q90-1987, Quality Management and Quality Assurance Standards: • Quality system—The organizational structure, responsibilities, procedures, processes, and resources for implementing quality management

• Quality assurance—All the planned and systematic actions necessary to provide adequate confidence that a product or service will satisfy given quality requirements

• Quality control—The operational techniques and activities that are used to fulfill requirements for quality

Note that these definitions don’t try to define what quality is, only the methods used to achieve a quality defined by customer requirements. However, over the last several decades the meaning of the word “customer” has been expanded to include internal customers as well as buyers of the end product. For example, the internal customer of a particular machining cell could be the plating department. Quality management systems will also address how the machining cell can address and solve quality problems in the “products” it supplies to the next user of its output. In an organizational definition of quality, all departments that interact with others are both “suppliers” and “customers” until the product actually reaches the consumer. Manufacturers have developed sophisticated quality assurance (QA) systems to control the manufacturing processes, so that the highest-quality products are made consistently. Achieving high quality in all phases of the manufacturing methods has several advantages for businesses: • Products are more competitive with competing models of similar features because of customer perceptions of value.

• Product deliveries are faster.

52 Manufacturing Processes, Part 4 • Scrap and rework costs are lower, with less raw material waste and non-value-added labor.

• Work-in-progress inventories can be lower, reducing inventory costs.

With such important factors determined by the success of the QA system, business leaders tend to put great emphasis on developing effective QA methods. A good quality assurance system plays a key role in the organization and day-to-day operations of the factory. Its functions include • Documenting quality processes and procedures—In every department from design to shipping, work must be performed in accordance with proven procedures that produce mistake-free work. The procedures are documented and changes are approved after review by appropriate departments. The QA system is documented in a formal QA plan, approved by company management, and followed by all departments.

• Translating quality specifications—Customer requirements are interpreted and implemented in every process. Special requirements are controlled by approved procedures for maintaining component identification through the manufacturing process. Procedures are specified and documentation is maintained by the factory to assure that the correct procedures were used.

• Maintaining instrument standards—All measurement equipment, such as meters, gauges, tooling, and instrumentation, is maintained in proper and traceable calibration condition. Documentation for calibration and repairs is maintained for all equipment that measures product performance in any way.

• Process capability studies—Manufacturing machines, equipment, and processes are analyzed to determine the highest level of performance possible with a given combination of machines, materials, and workers.

Manufacturing Processes, Part 4 53 • Data collection—Manufacturing performance data is collected for quality control analysis with tools such as statistical process control (SPC). Records are maintained documenting process performance for auditing, warranty, or liability purposes.

• Failure mode and effect analysis (FMEA)—FMEA can anticipate the likelihood of events and consequences for product failures, and procedures can be implemented that lessen the consequences of those failures that do occur.

• Disposition of nonconforming material—Products or parts that are out of specification are isolated by controlled procedures to prevent their being used in or mixed with good products. The source of the defects are isolated and solved to prevent future failures or scrap.

• Manufacturing processes verified—Critical processes such as welding or assembly procedures are “qualified” to ensure they’re suitable for the design. The use of qualified procedures is documented for all manufactured products.

Given the importance of the quality management systems for producing quality products at competitive cost, quality management personnel have moved to ever-higher positions in businesses, often becoming vice-presidents. These managers are responsible for the total quality management within the organization. Some of the more important characteristics of total quality management systems include a strategic plan; education and training for every employee; the use of quality measurements and statistical methods to measure performance and process control; objective customer satisfaction measures; and bench- marking all business processes and products to compare them with goals, or against known leaders in the business. Figure 27 shows a diagram of the basic framework of a total quality management plan and many of the major components.

54 Manufacturing Processes, Part 4 FIGURE 27—Most quality management systems address all of the major functions of a business, Total whether a manufacturing or Quality service-type business. Plans Management should emphasize measured Quality performance, accurate data, and feedback to Management correct system flaws.

Quality Assurance

Quality Control

Inspection Metrology

ISO 9000—An International Standard

Many manufacturing firms have their own QA plans that are written just for their business; others follow standards developed and maintained by organizations such as the American Society of Mechanical Engineers (ASME), or the International Organization for Standardization (ISO), with its well-known ISO 9000 series of QA standards. Having a good QA system is of great value to a modern manufacturing business. Participation in recognized QA systems such as the ISO 9000 is voluntary, but in some cases—when work is performed for government agencies or with government funds, for example—product or performance specifications for implementation of a recognized QA system practically has the power of law. The International Organization for Standardization was founded in 1946 in Geneva, Switzerland, to establish worldwide common standards for manufacturing, communications, and trade. More than 90 countries currently participate; the American National Standards Institute (ANSI) is the body that represents the United States. The organization’s 180-odd subcommittees draft standards with the help of technical advisory groups, and have issued more than 8,000 standards in most areas with the exception of electrical and electronic engineering.

Manufacturing Processes, Part 4 55 One reason that the ISO 9000 quality standards have become so important is that in the late 1980s, the European countries developed a common market, where any country could buy and sell products with the others while maintaining consistent quality and performance. Common standards reduced inspections and acceptance test costs when products were sold in other European countries. With the adoption of these standards, U.S. products sold in the European community had to conform to the same standards or risk significant economic penalties. Since then, many major American companies have adopted the ISO standards to develop or maintain European markets, and also because the standards are viable frameworks for developing superior QA systems. The ISO 9000 series is like other such systems in many ways. It requires a documented QA manual that addresses all aspects of the business: contract review, design verification, purchasing methods, material control, the use of certified or approved procedures, written work instructions, control of nonconforming items, and internal and external quality audits. An ISO 9000 plan involves all levels of personnel, from the president or CEO down to the machine operators (Figure 28). There’s a big difference between adopting the standards and becoming certified to the standard. Any company can adopt the standards to implement a QA system. However, certifica- tion involves asking an outside accrediting body to examine in detail the company, its operations, and its plan, in order to formally recognize its compliance with the standard. There are hundreds of independent accrediting agencies in the European community. In the United States, the only accrediting body was the Registrar Accreditation Board, until it was taken over by ANSI in 2005.

Six Sigma

Another QA system you’ll hear about is called Six Sigma, a quality management program that focuses on improvements to a company’s performance by identifying and eliminating defects in its processes. The name “six sigma” comes from the use of statistics and the normal distribution curve that describes the way variation occurs in random processes.

56 Manufacturing Processes, Part 4 Total Quality Management Requirements

Documented Management Management Quality System Responsibility Elements Training Quality Audits

Design Core Process Review Customer Contract Purchasing and Elements Order Review Control

Handling Control Shipped Storage of Non- Process Product Packaging Conforming Delivery Product Control

Warranty and Service

Inspection and Testing Statistical Techniques Foundation Elements Quality Records Document and Data Control

Corrective Action Control of Inspection and Prevention and Test Equipment

Product Identification Inspection and Test and Tracebility

FIGURE 28—ISO 9000 quality assurance plans involve every area of a business and all levels of personnel. The plan is based on extensive and accurate record keeping, and measured product data.

Manufacturing Processes, Part 4 57 When you graph measurements taken from any process, truly random—not caused by any external factors—variations (measurements that differ from the average) will cluster around an average value and in a predictable pattern. From a group of previous process measurements, it’s possible to calculate a value, called Sigma, which shows how much any new measurement is likely to differ from the process average. In six sigma, a defect is defined as any measurement that differs from the process average by six times sigma. Statistically, this value is unlikely, meaning that defects will only occur at a rate of about 3.4 defects per million measurements, which represents a very-high-quality process. The use of the term six sigma has moved away from the mathematical definition and has been applied to any product or process that satisfies customer requirements and minimizes production costs to achieve a maximum value to the business. Six Sigma was pioneered by Motorola Corporation in the mid- 1980s and has been adopted by other major manufacturers such as General Electric, Ford, Microsoft, Caterpillar, and Raytheon. Initially applied only to manufacturing, Six Sigma systems are now spreading to other types of businesses as a way of implementing total quality management systems. Six Sigma systems use several methodologies to achieve low-defect processes and products, as well as to develop new customer-focused products. The chart below summarizes these tools.

58 Manufacturing Processes, Part 4 Table 3 SIX SIGMA METHODOLOGIES

Existing Processes and Products New Processes and Products

DMAIC DMADV

Define – Measure – Analyze – Improve – Control Define – Measure – Analyze – Design – Verify

Define who are the customers, what are the Define goals of the design activity; what is requirements, what are their expectations; being designed and why; goals that are consis- project boundaries and the beginning and end tent with customer demands and business of the process; the processes to be improved strategies. by mapping flow and relationships. Measure the performance of the basic processes involved; develop a basic data Measure baseline abilities of current processes collection plan; measure data from multiple for future comparisons; define critical measure- sources to determine types and rates of ment needs; translate customer requirements defects; compare results to customer into project goals. requirements.

Analyze the data collected to determine possi- Analyze proposed processes for potential ble causes; gaps between performance and trouble spots and possible resolutions. goals; possible sources of variations

Improve the process by developing solutions Design the process and product to meet cus- using technology, training. tomer needs with an effective use of resources.

Control implementing of improvements, Verify the design performance and ability to document the changes; institutionalization of meet customer requirements and business the improvements by training, staffing changes goals. or additions or changes of equipment.

Tools Used for Six Sigma Projects:

• Customer surveys • Regression analysis

• Process flowcharts • ANOVA (analysis of variance)

• Stakeholder analysis • Brainstorming

• Histograms and Pareto charts • Failure modes and effects analysis (FEMA)

• Statistical process control (SPC) • Cause and effect diagrams (Fishbone charts)

As you’ll recognize, many Six Sigma processes and tools overlap other types of quality assurance and quality control techniques, and this has been one of the criticisms of Six Sigma plans. However, the useful focus of these techniques into a manufacturing management philosophy has well- documented successes in the companies mentioned above, and its applicability to a wide variety of business organizations makes it especially attractive as a framework for improvement.

Manufacturing Processes, Part 4 59 eManufacturing

No discussion of manufacturing management systems would be complete without mentioning eManufacturing, the term applied to the development and use of new communications technologies in manufacturing processes. The driving force behind eManufacturing was the arrival of the Internet around 1994 and the worldwide adoption of the communication standards that allow computers and other devices to communicate with each other, sometimes referred to as Transmission Control Protocol/Internet Protocol (TCP/IP). If you think about how the Internet has affected your life already, you can imagine how it’ll affect manufacturing firms in the future. Implementation of modern communications and computer technologies will allow better control of the basic manufacturing functions, with benefits such as reduced inventories, better manufacturing throughput, better delivery performance, reduced paperwork, and improved quality. Major manufacturing firms have demonstrated that moving to eManufacturing concepts can vastly improve their competitiveness. Some of the technologies and products that are now com- monplace and have greatly impacted our lives are • E-mail—We can instantly communicate over the entire globe to exchange information. E-mail can be used to send written instructions, pictures, software, music, electronic drawings, and documents.

• Wireless technologies—Cell phones and wireless devices such as the Blackberry allow voice and e-mail communications in real time, unconstrained by location. A cell phone lets callers reach you almost anywhere in the world at any time. Cell phone cameras let you send personal or business-related photos. Business computers are being networked in wireless environments, avoiding the use of expensive cables and the need to be physically connected to the network.

60 Manufacturing Processes, Part 4 • Computers—Modern computers are becoming smaller and more powerful, and better designed for the way we work: wireless hand-held devices function as organizers, note takers, and e-mail hubs; laptop computers are smaller and more powerful, and can be used with pencil- like styluses as if you were writing on a paper tablet; and powerful software exists for such business applications as simulation, engineering analysis, and 3D modeling and drawing.

• Data storage—In the mid-1980s, computers used hard drives that had storage capabilities on the order of 20–30 megabytes. Today’s hard drives hold several hundred gigabytes and more, or 10,000 times the former capacity! New storage devices such as “thumb drives” and memory cards are used in media that have no moving parts. Availability of high-density memory and computer chips will make many products “smarter” and more cost effective in the future.

The impact of these technologies will have a significant influence on manufacturing, both inside the factory and outside. Within the manufacturing environment itself: • Critical decisions can be made instantly by key personnel at the appropriate level, wherever their location, with access to e-mail, cell phones, and pagers.

• Shop floor data collection is instantaneous, accurate, and available to everyone who needs it to make management decisions.

• Modern building automation systems program and manage temperature, ventilation, lighting, fire control and alarms, and security from remote locations. Building automation systems have the potential to reduce energy consumption within buildings to achieve thousands of dollars in utility cost reductions annually.

Manufacturing Processes, Part 4 61 • Manufacturing services that can be digitized and sent to lower-cost organizations are outsourced to save money. These could include design services, CAD drawing, manufacturing prototyping, accounting and payroll, and advertising and marketing services.

• Inventory control and work-in-progress can be accurately tracked using RFID (radio frequency identification) chips embedded in or attached to products or materials. These tiny chips contain coded product information and even allow tracking of lost materials. Retail chains and libraries make extensive use of these chips for product ID and location.

How the business interacts with people and businesses outside the firm will be greatly affected by the ability to communicate rapidly and accurately. For example: • Supply-chain management will be handled entirely by communications technologies and software. Customers can place orders directly over the Internet, and orders can automatically be generated to sub-vendors so that trusted suppliers know when raw materials need to be furnished. Invoicing can be done electronically, shipping instructions can be placed, and accounting transactions can be recorded without intervention from on-site personnel.

• Electronic file transfers can allow vendors to manufacture parts, assemblies, and prototypes without intermediate steps. Electronic files can be sent over the Internet to approved vendors, who then send the files directly to manufacturing cells. Software can translate drawings into CNC program files to allow machines to make parts directly from electronically formatted drawings.

• Quotations for materials can be received electronically or online, with vendors bidding on items directly from spreadsheets e-mailed or posted online.

62 Manufacturing Processes, Part 4 • Manufacturing firms have access to vendors’ inventories and forecasts, to make accurate delivery predictions for wholesale or retail markets.

• Equipment suppliers can diagnose faulty machines remotely, while machines communicate with other machines for fault diagnosis, online corrections and repairs, and upgrading software.

• Voice-Over-Internet Protocol (VoIP) is making audio communications as reliable as local telephone calls for real-time communications with anyone in the world who has access to a computer with a physical, wireless, or satellite Internet connection.

These technologies will dramatically affect the way we live and do business. Manufacturing businesses will continue to integrate new technologies in a way that make them more competitive and let them reach new markets. Companies that don’t switch to this new way of doing businesses will face shrinking markets and higher costs. Figure 29 shows the structure of a typical eManufacturing organization. Individual manufacturing sites use information technology to improve the usual functions of maintenance, quality, and systems control with the use of accurate real-time data. Senior managers, who may not be located at the same facility, often have access to the same data to allow timely decisions about resources that affect customers and suppliers. Order management and planning and scheduling functions are even more tightly integrated to assure improved JIT manufacturing capability. While there are definite concerns about the implementation of Internet-based communication, such as the cost of communication infrastructure and security, most businesses see them as the price of remaining competitive. As these technologies are incorporated, manufacturing employees will continue to require different workforce skills. Manual or semiskilled machine operators must possess significant and diversified technical and problem-solving skills. Each skilled employee will continue to be an important component of the modern manufacturing facility, doing more with ever more sophisticated processes and machines.

Manufacturing Processes, Part 4 63 Supply Chain Suppliers Customers

Planning Senior Level Order and Planning and Management Management Scheduling Administration Level

Manufacturing Production Systems Manufacturing Sites

Maintenance Control Systems Quality

FIGURE 29—Typical Structure of an eManufacturing Organization

The Future of Manufacturing

What changes will occur in manufacturing in the future? Many of the changes occurring now will continue and accelerate in the near future, as the quality of the new technologies improves. We’ll see major growth in manufacturing capabilities of other countries around the world such as India, China, Southeast Asia, and even Africa. As the economies in these countries become more productive with higher quality, more manufacturing services and functions will be outsourced to these areas with less expensive labor costs. The products

64 Manufacturing Processes, Part 4 we buy as consumers, such as automobiles, power tools, appliances, or cosmetics, won’t change greatly, but where they’re manufactured and at what price will surely be different. What also will change are the products that are available. For example, research in nanotechnologies will undoubtedly produce new products for consumption in the future. Researchers at Intel, a major semiconductor chip manufacturer, say that major changes in chip technologies are necessary to significantly improve performance: we must be manufacturing at the molecular level during the next decade if we expect to maintain the current rate of technological advances. Successful manufacturing of products on the nanotechnol- ogy scale will require advances in many disciplines such as chemistry, physics, mechanical engineering, materials science, molecular biology, and computer science. As we learn to work at the nano scale, we can expect new products to appear. Exciting possibilities of new medicines, miniature machines to find and eliminate cancer cells, and miniature computers seem within reach when technological capabilities are projected forward to the future. Scientists say that to have useful technologies, we’ll have to build machines that build even smaller machines, and that useful large devices and products will require massive parallelism—many machines working on the same project at the same time. It’s possible to build very large objects using very small tools by having them work together in unison towards a common goal: a tree is a perfect example of molecular assembly on this scale! As you continue with your studies, remember that what you learn today has a half-life, in much the same way as radioac- tive materials have a half-life. As technologies and techniques progress, half of what you know will be obsolete in just a few years. It makes sense to prepare yourself for a continually changing future by making a habit of learning new things any way you can, from formal coursework such as these units to studying trade magazines and technical journals. One thing is for certain: not only isn’t your education over, it may be just beginning!

Manufacturing Processes, Part 4 65 Self-Check 4

Complete the following statements.

1. One of the main advantages of JIT manufacturing systems is reduction in ______.

2. ______refers to the effort to control the flow of materials all the way from the customer’s order to the raw material supplier.

3. The method of using cards or tickets attached to parts, batches, or pallets to control their location in the manufacturing process is known as ______control.

4. A key principle of lean manufacturing is the use of ______production systems instead of push systems.

5. An advantage of concurrent engineering is a reduced ______for new products.

6. ______within an organization is the philosophy and guiding principles that seek to continuously improve every aspect of a business.

7. ISO 9000 first originated in ______as an acceptable QA system.

8. eManufacturing resulted from the introduction of the ______around 1994, allowing rapid worldwide communications.

Check your answers with those on page 68.

66 Manufacturing Processes, Part 4 Self-Check 1

1. job description Answers

2. industrial engineering Answers 3. apprentices 4. factory 5. disposable income 6. standards 7. scientific management 8. production manager

Self-Check 2

1. production volumes 2. job shop format 3. job shop 4. batch 5. mass-production 6. continuous 7. continuous 8. job shop 9. 5S method 10. functional 11. Cycle time or Throughput time 12. cellular 13. Flow line 14. build-in-place

67 Self-Check 3

1. automation 2. closed-loop 3. fixed 4. Programmable automation 5. high, toxic or hazardous 6. payback 7. six 8. pick-and-place

Self-Check 4

1. work-in-place (WIP) inventory or costs 2. Supply-chain management 3. kanban 4. pull (demand) 5. time to market 6. Total quality management 7. Europe 8. Internet

68 Self-Check Answers Manufacturing Processes, Part 4 Examination Examination

EXAMINATION NUMBER 18607800

Whichever method you use in submitting your exam answers to the school, you must use the number above

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When you feel confident that you have mastered the material in this study unit, go to http://www.takeexamsonline.com and submit your answers online. If you don’t have access to the Internet, you can phone in or mail in your exam. Submit your answers for this examination as soon as you complete it. Do not wait until another examination is ready.

Questions 1–20: Select the one best answer to each question.

1. Work transfer stations A. often use simple robots for handling small parts. B. can’t be used when people remove the parts for some portion of the assembly operation. C. utilize only the most sophisticated six-axes-of-motion robots. D. are found only in build-in-place type manufacturing facilities.

2. Just-in-time manufacturing was developed in Japan A. for the transistor radio manufacturing facilities. B. to compete with job-shop manufacturing methods. C. to avoid shipping problems with raw material suppliers. D. to minimize WIP inventory costs and improve automobile quality.

69 3. As the operator in charge of the CNC milling machine in a manufacturing cell, you decide to make 100–200 parts more than are called for by your production manager to avoid future delays. Your decision results in A. a typical benefit of job-shop style manufacturing. B. an increase in WIP inventory. C. decreased product quality. D. decreased manufacturing times and no delays.

4. Cellular layouts are effective in certain high-volume applications because A. product quality isn’t dependent on worker skill. B. equipment use through all adjacent cells is easily optimized. C. material handling is simpler because of the proximity of related machines. D. cells usually don’t require close supervision.

5. You’re working in a finish-painting operation that’s undergoing a shift to lean manufacturing methods. Your supervisor asks you to stop photographing the parts that are sent from your operation to assembly. He probably does this because A. six-sigma inspectors can’t evaluate defects using photos. B. photos aren’t considered acceptable forms of documentation in ISO 9000 certified operations. C. your photos will interfere with the department’s JIT Quality system. D. photographing the parts doesn’t add value to the finished product.

6. As the supervisor of the assembly area in an electric motor manufacturing business, you notice that a group of motor housings has been rejected because of an oversized hole in the side of the housing. Since the assembly bolts will go through without any problems, you remove the housings from the nonconforming material area and send them to the assembly department for use in the final product. Your decision to use these parts will A. save the company money. B. reduce the amount of reworked material and thus manufacturing costs. C. probably violate your company quality assurance procedures. D. save overall time and money as the end result.

7. A rural area in Pennsylvania has a regional population of 82,000 and an unemployment rate of 8.9%. In evaluating the possible location of a large job shop in this area, one of the most important things you would need to consider would be the A. availability of highly skilled workers in the available labor pool. B. availability of batch-style manufacturers in the area. C. number of assembly-line workers in other area manufacturing businesses. D. number of mass-production facilities in the area.

70 Examination 8. A technician in a manufacturing cell reports a faulty velocity sensor on an actuator. Of the following, he or she is most likely referring to a problem with a component on a(n) A. aircraft-servicing scaffold. C. ship-building work platform. B. programmable robotic welder. D. mass-production conveyor line.

9. A quality assurance technician has collected performance data about the defects produced by a certain milling machine in a factory producing high-cost aviation parts. The data indicates that the machine produces parts with truly random variations in the critical dimensions, and no operator-caused variations. The next step the technician would take after collecting this data would be to A. try to improve the machining process by adjusting feeds and speeds or other manufacturing parameters. B. contact a manufacturing engineer about advanced machining process capabilities to decrease variations. C. analyze the process for potential trouble spots. D. determine if the variations meet customer specifications at an acceptable level.

10. A supplier of specialty prototype parts made from beryllium is likely to have ______as a manufacturing format. A. cellular layout C. assembly line B. job shop D. functional shop

11. While arranging for the installation of three new milling machines, you have a question about the best placement positions for the machines and their loading robots. For the best answer you would go see the ______of the factory. A. industrial engineers C. CFO B. product designers D. QA managers

12. Production managers must monitor and supervise critical factors such as A. QA audits, shipping schedules, and order entry. B. line maintenance, customer relations, and returned goods. C. worker training, equipment layout, and WIP inventories. D. capital costs, machine inventory, and value-added calculations.

13. The main factor that determines how manufacturing businesses are classified is the A. cost of the equipment. B. number of employees needed to run the machines. C. number of machines and equipment necessary for production. D. production volumes anticipated.

Examination 71 14. Fixed-automation devices A. aren’t used in modern factories. B. use mechanical means such as cams and gears to accomplish tasks. C. can be easily changed to programmable automation if necessary. D. can’t be used in automation on flow lines.

15. Mass production advantages include A. low capital costs and low WIP. B. low-cost machine tools and high cycle times. C. consistent product quality and low-skilled labor requirements. D. rapid product customization and high production volumes.

16. A method used to control work-in-progress by signals sent back to producing areas for replacement stock is A. JIT. C. TQM. B. kanban. D. DFM.

17. A robot needed to do a complicated three-dimenstional welding operation A. would likely be a one-axis pick-and-place model. B. would have either one linear or one rotational axis of motion. C. would likely be a continuous-path type robot. D. isn’t yet commercially available.

18. In automated manufacturing systems, smart actuators A. are those that operate without the need of controllers. B. can easily replace fixed automation devices to increase production rates. C. can increase cycle times and decrease WIP. D. have built-in sensors for position and velocity control.

19. One reason for extensively automating a manufacturing process is that A. low-skilled labor is inexpensive and easily available. B. production volumes are low. C. operations must be done in a hazardous environment. D. all prototype-building operations are highly automated.

20. A robot that can move a hand left and right and rotate the hand 360º is said to have ______axis (axes) of motion. A. one C. three B. two D. four

72 Examination