ARTICLE IN PRESS. LeanThinking. journalhomepage: Redesinging an Automotive Assembly Line Through Lean Strategy

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1 InternationalJournalofLeanThinkingVolume2,Isue2(December2011) LeanThinking journalhomepage: Redesinging an Automotive Assembly Line Through Lean Strategy K. P. Paranitharan * Department of Mechanical Engineering, PSG College of Technology, Coimbatore, , India Adres: paranik4@gmail.com M. Shabeena Begam Anna University of Technology, Coimbatore, India S. Syath Abuthakeer Department of Mechanical Engineering PSG College of Technology, Coimbatore, , India M. V. Subha Anna University of Technology, Coimbatore, India A B S T R A C T Today modern industry has contemporary market place due to strong competition for the survival and development forces, where companies seek in to more and more efficient & economics activity fulfilling the high expectation and requirements of customer for an affordable quality products & also continuous improvement of process make a long term market success. The focus of current approach is to review current manufacturing practices & visual identification of waste, based on the comparison and input review a modeled step by step procedure has proposed to infuse the lean concept implementation using five step approaches. In this paper provides the useful platform for further research in the implementation process of automotive industries and also other manufacturing industries. The result shows significant improvement in increase productivity, reduction in lead time, reduction in inventory and also eliminates the customer end line rejection. These can be achieved by creating flow by layout modification and balance to takt time. K E Y W O R D S Lean, Value Stream Mapping, Takt Time, Flow, Layout. A R T I C L E I N F O Received 14 May 2011 Accepted 17 May 2011 Available online 01 June Introduction and literature survey Today manufacturing industries in the world are restless, in the recent years challenges for the survival of any industry with emerging economics face situation with competitive power. Because of it many manufacturers have started implementing lean manufacturing practices. The goal of lean manufacturing system is doing more with less of time, space, human effort while giving the customer what they want to be highly economical manner. Today development of lean manufacturing system involve many changes in work culture and practices many of these changes are related to human factor with of lean behavior for the most effective and efficient manufacturing and assembly * Corresponding Author

2 practices. Womack et al. (1990) defined the term lean as that system that utilizes less in term of all inputs, to create the same outputs as those created by traditional mass production system, which contribute increased varieties for end customer. Lean focuses on removing wastes and ads value from customer perspectives, it is necessary to identify the non-value added activity and value added activity in the manufacturing system which creates wastes. Essentially a waste is anything for which customer is not ready to pay. The source of waste which involve the any of the undeterministic operation that in the production process which is not supporting the customer value about the product. There are different tools and technique in lean manufacturing is classified by Panvnaskar et al. (1998) to improve the waste in industry. The different kinds of lean waste and attempts made for elimination found in literature surveys which are found suitable lean tool and techniques of manufacturing practices. The various lean tools which are eliminating waste are value Stream mapping, kaizen, standardization of work, single minute exchange of dies, total productive maintenance, cellular manufacturing, kanban etc. Among the entire tool VSM is the one of lean tool which unveils all kind of waste and it is the only tools which link the information flow and material flow which are addressed by (Rother and Shook 1999). Value Stream Mapping (VSM) is the lean to which many author benefited in their problem area. Hines and Rich (1997) describing seven mapping tool for mapping the process. Gallone and Taylor (2001) have experienced benefitted in the field of logistics. Seth and Gupta (2005) have made a successful attempt to VSM as a technique to achieve the productivity improvement. Bhim and Sharma (2009) mapped the value stream of automobile crank shaft gear manufacturing to identify the improved areas of the firm. Paranitharan et al. (2011) has made an attempt to packaging box industry to bridge the gap between the existing state and proposed state of manufacturing process for productivity improvement and creating flow. Continuous improvement (kaizen) is the one of lean tools which benefited by Monden (1998) author has addressed in the area balanced to takt time which they match the production demand to customer requirement within the stated time and these are addressed in the areas of inventory and over production. Womack et al. (1990) has supported production smoothing area and they classified in to lean waste. Based on literature Survey addressed problems can be resolved by formulating five steps methodology to improve the process ratio of manufacturing process, reduce the lead time of entire stream and continues improvement over by implementing lean practice. 2

3 2. Methodology There are various steps in implementation in lean manufacturing are shown in Figure 1 and discussed in the following sections. The process analyses is carried out by collecting dataa from various enquiries with shop floor experts and directly participates in measuring the time involved in various assembly and machining processes. Figure 1. Methodology of Lean Implementation 2.1 Selection of critical part family The first step is the selection of the critical part family. After the throughh study of all Part families, one part family were rather preferred over alll the product families. That part which has high demand over other. Here brake actuator is used for study of leann implementation. 3

4 2.2 Preparation of current manufacturing scenario Interaction with the sales and marketing team information regards customer s requirements. It was understood, the company has a wide range of customers requesting for a wide range of product from different type of actuator. The requirement of brake actuator has Demand of 20,000/month and data collected to trash the opportunity for improvement. Based on data collection the production processes are mapped as shown in Figure Analyses the process with lean tool In this Production process are Analyses with appropriate tool to proper root causes of problem are stated already in the problem definition, which are examine with help of literature survey. And also based on the field experience of production experts the production problems are analyzed with appropriate lean tool. 2.4 Implement lean tool In this production problem are examined with appropriate lean tools are implemented to resolve by the kaizen process of production activity. In order to implement lean principles, a task of group formed with different part of organization. The objective of operation is to reduce the lead time, improve the process ratio, reduce the inventory and eliminate customer end line rejection. The methodology of five step lean implementation approach helps to achieve the objectives Present state value stream mapping To construct the current value stream, relevant information was collected based on the interview with assembly and machine shop. Data relevant to customer such as quantity, quality, supplier information and customer information are identified. The process cycle time, inventory, value added time and number of operator to perform the present state mapping. In value stream mapping the lead time and value added time are recorded on the bottom line that reveals present state conditions of production operations. In machining process of value stream flange machining operation which has high bottleneck time which is 155 seconds in the machining and in assembly Process it is 78 seconds. Mapping of process is carried out with a lead time of seconds and value added time is seconds with including stores in the present state mapping. The Figure 2 shows the reveals present condition process mapping. 4

5 Figure 2.. Present State Mapping Create flow In the assembly line during assembly process there is a back flow of material and operator motion due to improper layout design. The assembly of present layout material are placed separately in front of every work station, due to that more space is occupied forr assembly process and non-value addition of a part is increased. In order to avoid non value addition assembly line is modified by lean principle to creating flow. The Figure 3 shows the t existing layout of assembly process. 5

6 Flange Trolley OPN 20-Ram Assy A OPN 30-Cylinder Greasing Figure 3. Existingg Layout of Assembly Operation In the existing process there is separate assembly station for ram assembly andd cylinder greasing operation are not lesser value addition too product, due to that more m cost for manufacture. By modifying the layout where the material flow is adapted by integrating the operation sequence in the assembly process. In existing station more no of trolley, lot of space to be occupied, it indirectly results in cost to component. Based on the analysis of process integrating ram assembly and 6

7 cylinder greasing as a single workstation the work content of operator is reduced, process time t is reduced and ultimately it reduce the cost of assembly. Modular Trolley Figure 4. Modifiedd Layout of Assembly Operation The above Figure 4 shows the modified layout of assembly operations o designed with lean principle to create flow, single modular trolley is placed at input point instead placing separate material trolley for sub assembly workstation. By this integration of assembly operation and eliminating material trolley, has huge saving in assembly space which is from meters to 5.2 meters, because of this improvement assembly processing time is reduced and lead time is reduced. 7

8 2.4.3 Balance to takt time In this balance to takt time where all thee process time of value stream are reduced below the takt time, in which flange machining, ram machining, assembly cycle time are bottleneck operation of entiree value stream. To improve process and meet the customer demand on timee bring the process time below the takt time. The Figure 5 shows operation cycle time exceeds the takt time. Bottle operations Figure 5. In-house Bottleneck Times In this in- house process the bottleneck time of flange machining is 156 seconds, ram machining is 91 seconds, assembly cycle time is 788 seconds, which are time consuming with of these bottleneck time of value stream are not able to meet the customer demand at right time. To meet the customer demand on time every product should produce in the frequency y of 70 seconds, by improve the process of each in-house bottleneck time to focus on their Production process. In flange machining process previously they are using Gravity Die Casting (GDC) which is i time consuming and hourly outputt of machine is low, cost of casting iss high and many no of drilling operation is to be performed and not able to make quality holes during casting. Alternatively to improve the process instead of using GDC, by proposing Pressuree Die Castingg (PDC) which has many advantages than GDC, hourly output is more in that machine, Quality hole is produced at the time of casting and cost of casting is less compared to GDC, here by suggesting PDC to manufacture the casting for assembly operation. In flange machining operation there t are rough finishing, fine finishing operation for flange machining operation, there is separatee tool setup for each machining operation and it total cycle time is 156 seconds, use of PDC with combined tooll single setup time of machining component consume least operation cycle time. So, it i reduced from 156 seconds to 8

9 68 seconds. Figure 6 shows conversions c of GDC to PDC casting inn brake actuator type 20/24 to elimination of machining operation in casting layout. Without holes while casting by GDC Holes during casting by PDC Figure 6. Comparison off flange machining and casting layouts s The Figure 7 shows the comparison of machining time, it results to t balance the takt time. Time (sec) Before After Figure 7. Comparison of Machining Time For improving assembly process duringg testing conventional adaptor is used for air entering in to actuator. To connecting the adopter andd tighten manually which take 78 seconds. Instead of use of Weh connector, eliminate tightening it reduces the time to 65 seconds. And also it reduces the operator fatigue. 9

10 Figure 8. Kaizen Theme of Assembly Testing During final assembly workstation company labels are usually pick from stand and pasted manually from label sheet, contain lot of non-value added activity and use of Label dispenser is introduced then activity time iss reduced from 9 secondss to 5 seconds. Figure 9. Benefits of Balance to Talk Time 3. Results and Discussions The implementation of lean approach to production process results in reducing the inventory from 4.1 days to 1.88 days. By eliminatingg non value added activity in the process, lead time of value stream is reduced from 81.9 hrs to 28.8 hrs. This entire product in a value stream produces product in less value addition and a increase hourly outpu of component from 5.55 nos to 8 nos. And finally achieve the zero customer end line rejection of component byy Zero defects approach, All the process of implementation are continuous monitoring and reviewed for further improvement.. 10

11 Figure 10. Future State Mapping 11

12 3.1 Graphs are enclosed to visualize the lean implement benefits Figure 11. Comparison of inventory Figure 12. Comparison of lead time Figure 13. Comparison of productivity Figure 14. Comparison of zero defects Before Figure 15. Comparison of In-house Bottleneck Time After 12

13 4. Conclusions The lean implementation study is proposed to give a comprehensive system lean approach towards the traditional manufacturing. This research carries evidence of genuine advantages of applying lean principles in a brake actuator manufacturing industry. In this present work provide elimination of non-value added activity from this process and it increase the process ratio from 3.98% to 10.6%. It can be concluded that lean approach in traditional manufacturing system is effective tool to identifying the process waste and current work propose to reduce the non-value added activity,shorten the lead time in the confrontational environment, Eventually it enables the companies to move towards their Ultimate goal leading to, sustainability and profitability. Reference Gallone P., and Taylor, D., From value stream mapping to the development of lean logistics Strategy: a case study, Manufacturing Operations and Supply Chain Management: the Lean Approach, Thomson Learning, London, 2001; Hines, P. and Rich, N. The seven value stream mapping tools, International Journal of Operations and Production Management, 1997, Vol.17, pp Monden, Y. Toyota Production System: An Integrated Approach to Just in Time, 2nd ed., Industrial Engineering and Management Press, Norcross, GA Pavnaskar, S.J., Gershenson, J.K. and Jambekar, A.B., Classification scheme for lean Manufacturing tools, International Journal of Production Research, 2003; Vol. 41, pp Rother, M. and Shook, J. Learning to See: value stream mapping to create value and eliminate muda, Lean Enterprise Institute, Cambridge, MA Seth, D. and Gupta, V., Application of value stream mapping for lean operations and cycle time reduction: An Indian case study, International Journals of Production Planning and Control, 2005; Vol. 16No.1, pp Paranitharan, K.P., Syath abuthakeer, S., and Mohanram P.V, Application of Lean Value Stream Mapping in Packaging Box industry, National Conference Proceedings of EMSDM Singh, B. and Sharma, S.K., Value stream mapping as a versatile tool for lean implementation: an Indian case study of a manufacturing firm, Measuring Business Excellence,2009; Vol.13.No3, pp Taylor, D. and Brunt, D. Manufacturing Operations and Supply Chain Management: The Lean Approach, Thomson Learning, London

14 Womack, J.P., Jones, D.T. & Roos, D., The Machine That Changed the World: the story of lean production, New York: Rawson Associates,