Journal of Engineering Research and Studies

Research Article

APPLICATION OF SYSTEM FOR IMPLEMENTING LEAN (A CASE STUDY) 1 2 3 B.Vijaya Ramnath, C. Elanchezhian and R. Kesavan

Address for Correspondence

1,2 Research Scholar, 3Asst. Professor, Department of Production Technology, Anna University, MIT Campus, Chennai-44, Tamilnadu Email: [email protected] ======ABSTRACT This paper deals with implementation of in Engine valve machining cell in a leading auto components manufacturing industry in the South India. The main objective of this paper is to provide a background on lean manufacturing, present an overview of manufacturing wastes and introduce the tools and techniques that are used to transform a company into a high performing . Value stream mapping is a main tool used to identify the opportunities for various lean techniques. The focus of the lean manufacturing approach is on cost reduction by eliminating Non- Value added activities. Applications have spanned many sectors including automotive, electronics and consumer products manufacturing. In this paper, Value Stream Mapping (VSM) is used to map the current operating state for production line. This map is used to identify sources of waste and to identify lean tools for reducing the waste. To eliminate the wastes found from the current state map Kanban system is suggested for pre machining section and single piece flow concept is suggested for machining section. Then a future state map has been developed for the system with lean tools applied to it KEYWORDS: Lean manufacturing, Value Stream Mapping and Kanban System

1. INTRODUCTION system focused on and driven by customers, Many manufacturers are now critically both internal and external. evaluating their processes to determine their The aim of Lean Manufacturing is the effectiveness in bringing maximum value to elimination of waste in every area of customers. Factory management techniques production including customer relations, of yesterday are being replaced by more product design, supplier networks, and efficient methods that greatly minimize factory management. Its goal is to delays, reduce costs, and improve quality. incorporate less human effort, less Lean manufacturing is a whole- systems , less time to develop products, approach that creates a culture in which and less space to become highly responsive everyone in the organization continuously to customer demand while producing top improves processes and production. It is a quality products in the most efficient and JERS/Vol. I/Issue I/July-Sept. 2010/138-151

Journal of Engineering Research and Studies

economical manner possible. of products. In accordance a leading valve Essentially, a "waste" is anything that the manufacturing unit in South India who are customer is not willing to pay for. Typically interested in implementing the lean the types of waste considered in a lean manufacturing concept. manufacturing system are Overproduction, 4. STUDY OF MANUFACTURING Waiting, Inventory or Work in Process METHODS AND SEQUENCE OF (WIP), Processing waste, Transportation, OPERATIONS Motion and Making defective products. The following sections show the processes 2. METHODOLOGY and sequence that have been currently done The following steps are involved in the in the company to bring the final product implementation of lean manufacturing. (Engine Valve) from the raw material which • Choosing a product or product family and is stored in the raw material store. Study of manufacturing methods and 5. CURRENT STATE FOR PASSENGER sequence of operations. CAR ENGINE VALVE MANUFACTURING • Study of layout and Construction of LINE Current State Value Stream Map. Data collection for the material flow started • Identification of Wastes and Looking out at the shipping department, and worked for the methods to eliminate these wastes. backward all the way to the upset and forging process, gathering snapshot data • Construction of Future State Value Stream such as inventory levels before each Map and Implementation of the proposed process, process cycle times (C/T), number concept. of workers, and changeover (C/O) times, • Analysis of economical benefits associated materials handling system etc., for the with proposed concept. current state mapping. The Value Stream 3. CHOOSING A PRODUCT OR Mapping for the passenger car engine PRODUCT FAMILY valve manufacturing line has been drawn. It would be highly creditable to implement By analyzing the Value Stream Mapping, the concept of lean manufacturing in an the following activities are found as the organization which has smaller more flexible wastes. machines that are typically organized into work cells devoted to production of a family JERS/Vol. I/Issue I/July-Sept. 2010/138-151

Journal of Engineering Research and Studies

Fig 1: Present Manufacturing Line The operations, head diameter turning and grinding of valve seat is necessary, but grooving & chamfering have been done by before that the valve seat turning is not two consecutive machines. Two necessary as it have currently being done. consecutive grinding operations have been Therefore it is the waste process. The same done by two consecutive grinding end finishing operation has been done at machines. Two valve seat grinding two different stations. The semi finished machines have been used to meet the products in batches are moved manually customer demand. This is due to the between stations. This leads to excessive incorrect selection of grinding wheels. The transportation waiting of products. Loading JERS/Vol. I/Issue I/July-Sept. 2010/138-151

Journal of Engineering Research and Studies

and unloading activities are done at each product. This above wastes indicates the station and therefore it needs one operator improvement opportunities from current at every station and it also leads to line. By going through these wastes, the operator fatigue. Most of the machines methods to eliminate or reduce these wastes have its own inspection stations even are to be found. Then the Future State Map though the inspection does not add value to be drawn considering with the improved to the products. Moreover the machining methods. Then the two maps are to be process is stopped when the inspection is analyzed to compare the economical done. The operators are idle, in most of the benefits Future state over current state. stations, while the machine process the Table 1 : Current State for Passenger Car Engine Valve Manufacturing Line Process Cycle Value Change NO. WIP Loading Unloading NO. of Method Time Added Over of m/c per of in sec Time Time in opera- operator Trans- in sec tor ferring sec Rough 13 11 600 1 200 Manual Auto 1 Manual grinding Head 18 15 300 1 0 Auto Auto 1 Manual diaturning Grooving 10 8 300 1 500 Auto Auto 1 Manual and chamfering Finish 5 3 300 1 1500 Auto Auto 1 Manual tappet end I Intermediate 14 11 900 1 1500 Manual Auto 1 Manual grinding Finish 14 12 900 1 0 Manu Auto 1 Manual grinding al Flame 15 13 0 1 1000 Manual Manual 1 Manual Hardening

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Seat 14 11 300 1 1000 Auto Auto 2 Manual grinding Finish 5 3 300 1 1000 Manual Auto 1 Manual ta ppet

6. ELIMINATION OF WASTES BY 6.4 Functions of Kanban system PROCESS IMPROVEMENTS • It provides pick up or transport information. 6.1 Kanban System for Pre Machining • It provides production information. Section • It prevents over production and excessive 6.2 Introduction to Kanban System transport. The word Kanban has come to stand for a • It serves as a work order attached to goods. variety of items ranging from shelves, bins, • It reveals existing problems and maintains electronic messages and order slips to the inventory control. entire reorder point system. It is a small 6.5 Criteria to select Kanban items piece of a large puzzle. Kanban system • Self certified items, that are past 6 months guides everyone in an industry from machine there is no quality issue. operator to trolley driver to know what the • For stable process. next process to be carried out 6.3 Kanban Technique • For tools life monitoring system The technique that makes the JIT principles • Once in 3 months raw material inspection practical is called KANBAN. KANBAN is report must be submitted. a Japanese word meaning signboard or • Once in 3 months layout inspection report billboard. (Kan = visual, Ban = card). must be submitted. Kanban is a signal to replace what has been • Any process change must be approved by used. If the authorization is present, one can customer. act. If it is not one can’t. KANBAN is • Special process must be approved by customer. therefore a way of controlling inventory. In earlier days Kanban is the special 6.6 Kanban flow diagram manufacturing system proposed by

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6.7 Types of Kanban Unnecessary inventory is very important as

The kanban system is based on use of cards it affects more, the cost of production. We called ‘’. The card is put in a can call this production as a ‘Push rectangular vinyl slack. The following three Production’ as the machine stations in the kinds of cards are normally used: manufacturing line produces the valves based

• Move kanban on the capacity of the machine station not based on the demand. And also a WIP of 3 • Production kanban days of demand are maintained along the • Supplier kanban manufacturing line. Kanban system is an

To make kanban system work, manufacturing information system to harmoniously control processes are designated as preceding process the production quantities in every process. and subsequent process. The withdrawal We have suggested that this Kanban system kanban details the quantity that the can be implemented to reduce the inventory subsequent process should withdraw, while in the pre-machining section (Raw material, the production ordering kanban shows the Upsetting & forging and Heat treatment). quantity preceding process should produce.By The Kanban system is based on the use of drawing the Value Stream Map as a tool, cards called “Kanbans”. The card is put in a a number of wastes were listed out in the rectangular vinyl slack. The following are the current manufacturing line out of which two kinds of cards normally used. JERS/Vol. I/Issue I/July-Sept. 2010/138-151

Journal of Engineering Research and Studies

• Withdrawal Kanban (WK) details the quantity that the subsequent

• Production Ordering Kanban (POK) process should withdraw, while the

To make Kanban system work, Production Ordering Kanban (POK) shows manufacturing processes are designated as the quantity which the preceding process preceding process (PP) and subsequent should produce. These cards circulate within process (SP). The Withdrawal Kanban (WK) the factory (Pre-machining section).

6.8 Kanban Job Flow

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6.9 Number of Kanban Cards

Where, the bottle neck (2 hour round trip) that can be in a batch to do the heat treatment process or station is Heat Treatment in our process is 500. case because the optimum number of parts

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Number of WKs = 1, Number of POKs = 1

Number of WKs = 1, Number of POKs = 1

Total Number of WKs = 2, Number of POKs = 2 Therefore Total cards in the pre-machining section = 8 Kanban cards.

A trial had taken for the Kanban movement with time for a part of a shift starting at 6:00 JERS/Vol. I/Issue I/July-Sept. 2010/138-151

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am and ending at 2:00 pm (8 hour shift). The time. following table shows Kanban movement with Table 2: Kanban Movements with Time Time Raw material Forging Heat treatment total CAR SS WK U FGS POK SS WK U FGS POK SS WK U FGS POK DS P P P P P P P P P

6:00 1 0 0 1 0 1 0 0 1 0 2 0 0 2 0 8 6:01 1 0 0 1 0 1 0 0 1 0 2 0 0 1 1 8 6:05 1 0 0 1 0 1 0 0 1 0 1 1 1 1 0 8 6:10 1 0 0 1 0 1 0 0 0 1 2 0 1 1 0 8 6:15 1 0 0 1 0 0 1 1 0 0 2 0 1 1 0 8 6:20 1 0 0 0 1 1 0 1 0 0 2 0 1 1 0 8 6:25 0 1 1 0 0 1 0 1 0 0 2 0 1 1 0 8 6:35 1 0 0 1 0 1 0 1 0 0 2 0 1 1 0 8 6:40 1 0 0 1 0 1 0 0 1 0 2 0 1 1 0 8 8:00 1 0 0 1 0 1 0 0 1 0 2 0 0 2 0 8 SS – Safety Stock , WKP – Withdrawal Kanban Post, UP – Under Processing ,FGS – Finished Goods Store POKP – Production Ordering Kanban Post 6.3 Waste Elimination and Layout up stage grinding operation. The diameter will be gradation in Machining Section equal to (5.95-0.375). Hence the inventory In the machining shop there are three stages gets reduced. The second waste which we for grinding the stem. The purpose is to reduce can eliminate is by using a single cutting the diameter from 5.95 to 5.469. The tool. Turning of head diameter, valve seat, amount of material removal in each stage is chamfering at head and tappet grooving, 0.375, 0.092, and 0.014mm. Since the finish facing and chamfering are done at two grinding is required the operation is stations even though they are consecutive mandatory but we can eliminate the operations. Since these operations involve intermediate grinding operation by purchasing lathe, this can be combined and done in a the bar of the size which comes after the first single station. The third waste which we can

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eliminate is by eliminating the finish tappet end operation1. Since this operation is to check the overall length of the valve to correct size this can be performed at the end before the final inspection.

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Table 3: comparison between current and future state Benefits Current state After implementation of future state O/P per shift 2000 2000

No. of operators in 9 5 machining Productivity per operator 222 400

Transportation of Manual Automatic material b/w Machining section layout Straight layout ‘U’ layout

Loading and unloading Manual Automatic

Inventory at pre machining 12000 4000 (1 day demand) section (3 days of demand)

Inventory at machining 12000 Single piece flow section (3 days of demand)

This operation can be performed by the this effectively reduces time and manpower. grinding operation without changing any In the second stage of operation seat turning alternate machinery or setup. Hence the is one of the operations. Instead of doing required length can be obtained. The fourth this operation if forging operation is item which we can eliminate or reduce is performed to an extend that the seat parameter the inspection as it will not add any value to is brought to a level of what it will be after the product. Since one engine valve is being the seat turning operation then seat turning inspected for about four minutes involving operation can be eliminated. Hence we can three members this can be modified by directly perform the seat grinding operation adopting a simple but effective method. We thus reducing the time needed for the can adopt the multi gauging system based on particular seat turning operation. machine vision system. This system takes just 7. CONCLUSION about 10 seconds to inspect the valve. Hence Thus, the value stream maps for the current JERS/Vol. I/Issue I/July-Sept. 2010/138-151

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state and future state for both pre machining Manuacturing, Macmillan India ltd., India. 8.William A Sandreas Jr. (2000), Just in Time: and machining sections have been drawn. The making it happen, John Wiley and sons Inc. future state map is drawn after the elimination 9.Paul Zipkin (1991), Does Manufacturing Need A JIT Revolution? , Harvard Business Review. and or reducing of wastes which were found 10.James P. Womack (1990), The Machine that changed the world, Harper Perennial, New York, from the current state map. The necessary US. were implemented in the process to 11.J.T. Black and Kavit. R. Antani (1991), Insight in Lean reduce the wastes. The future state map was Production System, Journal Manufacturing System, SAE Transaction. developed for the system with lean tools 12.S. Grewal (2004), Development Model for Lean applied to it, which will improve productivity Improvement – A case study in automobile industry. to a greater extent. The elimination and or reducing of wastes is by making the process improvements in the current manufacturing line by adopting some lean tools like JIT, set up time reduction, WIP reduction etc. 9. REFERENCES 1. Fawaz A. Abdulmalek and Jayant Rajagopal (2007) ‘Analyzing the Benafits of Lean Manufacturing and lue Stream Mapping via Simulation: A Process Case Study’. Int. J. Production Economics Vol, pp.223-226. 2. Rother M. and Shook J. (1999), Learning to see: ‘Value Stream Mapping to Add Value and Eliminate Muda’. Lean Enterprise Institute, Brookline, MA. 3. Wagner C. and Abdulmula A. (2001) ‘Design and Evaluation of Lean Manufacturing Cells: A Simulation Model’. IIE Annual Conference. 4. William G. Sullivan et al., (2007) ‘Equipment replacement decisions and Lean Manufacturing’. Robotics and Computer Integerated Manufacuring Vol 18 pp.255-265. 5. James B. Dilworth (1993), Production and operation management, McGraw-hill Inc., New York, US. 6.Ohno. Taiichi (1998), Just-In-Time for Today and Tomorrow, Productivity Press. 7.Korgaonkar M G (1992), Just In Time

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