Component Manufacturing Company Using Kaizen. D. Rajenthirakumar, P. R.
Thyla. Abstract. The implementation of lean manufacturing strategy allows ...
Quality and Productivity Improvement in Automotive Component Manufacturing Company Using Kaizen D. Rajenthirakumar, P. R. Thyla Abstract The implementation of lean manufacturing strategy allows strengthening the phase sequence that leads to operational excellence, a continuous improvement and the elimination of non value added activities [1]. Thus, the influence of lean practices contributes substantially with the operating performance of plants [2, 3] and use of lean tools allows the improvement of results [4]. The tool kaizen is applied as a way to progress toward lean manufacturing and as a formula to lead the activities of improvement [5]. It has been increasingly adopted as a potential solution for many organizations, particularly within the automotive [1, 6] and aerospace [7–9] manufacturing industries. This work addresses the implementtation of the lean tool kaizen in an automotive component manufacturing company with a focus on tube sub-assembly line. The main objective is to develop several strategies to eliminate waste on the shop floor. This paper describes how the value stream mapping (VSM) and other suite of lean tools such as kaizen can be used to map the current state of a production line and design a desired future state. A significant increase in quality and productivity is confirmed and the production flow was smoothened by elimination of several non-value added activities. Keywords: Kaizen, Productivity, Quality, Value stream mapping (VSM)
1 Introduction Lean manufacturing is one of the initiatives that many major businesses have been trying to adopt in order to remain competitive in an increasingly global market. The focus of the approach is on cost reduction by eliminating non value added activities. Originating from the Toyota Production System, many of the tools and techniques of lean manufacturing (e.g. just-in-time, cellular manufacturing, total productive maintenance, single-minute exchange of dies, production smoothing, kaizen) have been widely used in discrete manufacturing [10, 11]. Applications have spanned many sectors including automotive, electronics, white goods, and consumer products manufacturing [9]. The Indian automotive component manufacturing industries have gained significant stride due to growing domestic demands and the outsourcing of components. According to the Automotive Component Manufacturers' Association of India (ACMA), the domestic Indian auto component manufacturing industry is heading for a whopping 18% growth in the coming years compared to the export market which is $2.7 billion in the year 2010. According to a joint study conducted by ACMA and Ernest and Young, the automobile industry is projected to be a five million units industry by 2015 and over 9 million by 2020. The industry can potentially be contributing 3.6 percent of gross domestic product (GDP) by 2020, up from the current 2.1 percent [12]. In order to achieve the improved market share and compete with their global counterparts, these industries necessarily need to improve productivity while ensuring lower cost and world class quality. However, it is strongly believed that unnecessary capital investment is not going to solve the problem; rather, this will turn out to be a waste in the long run. In this direction, the implementation of lean principles is highly recommended, in order to identify the areas generating waste; thus, it further facilitates the optimization of the operating conditions in a minimal investment. This paper presents a case study of a large-scale automotive component manufacturing industry which needs to improve the productivity in one their tube sub-assembly lines. The work focuses on the implementation kaizen philosophy whis addresses continuous improvement not only in mana-
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gement, but also in the general workforce [1].
2 Brief literature review In recent years, much literature has extensively documented the implementation of lean tools into various manufacturing sectors. Improving quality and productivity to gain a competitive advantage has always been a major issue for most manufacturing industry. A manufacturer, therefore, should always try to use advanced manufacturing technology to adopt better management. Kaizen is one of the approaches that have been applied to numerous industries, and many successful experiences have been reported. Kaizen, meaning (continuous) improvement, is as a key factor in the economic success of Japanese industries. With "traditional" techniques such as quality circles and management circles, kaizen may turn a profitless company into a profitable one without an enormous investment in equipment [13]. The successful application of kaizen and various lean tools had a profound impact in a variety of industries, such as aerospace, computer and electronics manufacturing, forging company [14], process industry (steel), and automotive manufacturing [15]. Their methodology is similar, using lean tools, and they are adapted to the study variables, but the improvement point and the results achieved are different. Considering the available literature, the present work is the first attempt that explores the degree of use of lean principles in automotive component manufacturing industry and provides direction for future continuous improvement.
3 Problem definition The objective of this paper is to use a case-based method to demonstrate how lean tools like kaizen when used appropriately, can help the industry eliminate waste, improve productivity and product quality. A large scale automotive component manufacturing company’s tube sub-assembly line is used to illustrate the method followed. The company produces drag links, centre links and tie rods for India’s major car manufacturing companies. The typical operations involved for making the CDS and CEW: 50*6, 40*5,
45*4.5, 26*5 types of tube are tube heating, squeezing single and double bending. The various component groups handled by the product assembly line are double side squeezed tube, single side squeezed tube, single bending with and without squeezing and double bending with and without squeezing. Tab. 1 summarises the overall nature of the assembly line. The company was experiencing severe pressures, both internally and externally, to improve the quality and productivity of the assembly line. In the pursuit of consistency, the management decided to implement lean tools. After several brain storming and a thorough study of the shop floor, it was observed that the tube subassembly line consists various forms of non-value-adding activities, such as high lead time, accumulation of high inventory, unnecessary material flow, high material travel distance, poor Mean-Time-Between-Failure (MTBF), under utilized man power. Tab. 1 Assembly line characteristics Sl. No. Description 1. 2. 3. 4. 5. 6. 7. 8. 9.
Nature of production system Set-up time: Bending – 50 min, Heating - 30 min, Squeezing – 45 min Transfer of material Mean time between failure Total man power Work-In-Progress Material travel distance No of machines involved Space occupied
Data Batch production 125 min Manual 6 days 18 per day 2200 units 62 ft 7 899 sq. ft.
In order to implement lean tools, a task team was formed with people from different department of the company, all having wealthy knowledge and information pertaining to production, machinery, scheduling and planning. The prime objective is to develop different strategies to reduce the level of non value activities present in any form by implementing the various lean tools. The research targets for the task team are: reducing change-over time to 10 minutes, increasing the line productivity by 25% and reducing the WIP to 200 units
Fig. 1 The present state value stream map
4. 1 Reducing change-over time After a detailed study and analysis of the standard work procedure and thorough investigation on the assembly line, it was found that the change-over time contributes signifycantly to the total processing time. Reducing the changeover time in any manufacturing system is a continuous improvement process. Fig. 2 shows the methodology adopted for reducing the change-over time reduction. The various elements associated with change-over time are identified and different strategies are implemented to reduce the change-over time. The standard work elements and work element time is measured, documented and classified as internal and external. In order to reduce the total changeover time, various strategies such as data documentation, method and time study, review of standard work procedure and continuous monitoring are adopted.
Fig. 2 Methodology adopted for change-over time reduction 4.1.1 Kaizen Keeping the change-over time reduction during bending process as an objective, the kaizen procedure followed is shown in the flow chart (Fig. 3).
4 Implementation and results In order to visualize the non-value-added activities it was decided to first construct the current state value map. Relevant information from various departments is collected to construct the current state value stream. Information related to the assembly line, such as cycle time at each work stations, machine down time for each process, inventory, change-over time, set-up time, number of workers and operational hours per day are also collected and documented properly. Cup pressing, tube heating, squeezing and tube bending are the major activities associated with tube subassembly line. To complete the value map, a timeline is added at the bottom of the map recording the total processing time and the value-added time. Finally, the value stream map for the current state is constructed as shown in Fig. 1. From the current state value map, it is found that only 101 seconds were value added activities, compared to 80640 seconds of non-value-added activities. The following sub-sections describe a planned and integrated approach adopted to reduce the non-value-added activities.
Fig. 3 Flow chart of kaizen procedure
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Step – 1: Form the team and gather information In this step, the facts of the process and the direction for improvement are examined. This information will be used in the next step, the current process, to gather information about the process. Step – 2: Description of the process Utilizing the kaizen methodology, the team will select the aspect of the process most in need of improvement. Step – 3: Decide goal of the team After gathering detailed information about the current process, the kaizen team identified the goal, which took into consideration the directions of the management. In this case, the team decided to focus on improving the method of tube bending process. This improvement was expected to reduce 50% of the set up time of that process. This reduction of time was, in turn, expected to reduce the change-over time and manual effort. Step – 4: Alternate methods – 1. Standardisation of height blocks 2. Adjustable socket locator Following the Kaizen methodology, the Kaizen team developed twenty ideas to improve the bending process. Fig. 4 and Fig. 5 demonstrate two such alternatives at a glance.
Fig. 4 Kaizen 1: Standardisation of height blocks
(a) Before kaizen
(b) After kaizen Fig. 6 Kaizen Accomplishment: New improved tube off-set checking method Tab. 2 Improvements after new off-set checking method Processing time in seconds Sl. Activity No. Before After Kaizen Kaizen 1 Tube off-set checking 300 30 2 Lifting the previous fixture 240 80 3 Moving the unloaded fixture 150 60
Fig. 5 Kaizen 2: Adjustable socket locator Step – 5: Evaluate and select the best solution The thirteen best kaizen among the twenty solutions are selected to improve the tube bending process took into consideration the directions of the management. Step – 6: Simulation and evaluation To confirm the possibility of implementing the methods by the Kaizen team, a simulation was undertaken. The team decided to see if it was possible to reduce the change over time with reduced human effort. To do this, the team used Arena, one of the most powerful simulators with the animation function and an easy-to-use interface. The results show that the change-over time during the bending process is reduced from 2815 sec to 755 sec which is 73% changeover time reduction. Step – 7: Accomplishments The kaizen team also developed a new improved off-set checking method (Fig. 6) for the tubes. Tab. 2 summarizes the results achieved by this improved method.
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4.1.2 Squeezing process: Set-up time reduction Similar to the kaizen procedure followed for the tube heating process, two improvement initiatives are generated and successfully implemented during tube squeezing. As a result, the set-up time during the squeezing reduced 78% (from 2600 s to 580 s).
5 Conclusions Due to increased customer expectations and global competition, the automotive component manufacturing companies are desperately trying to improve productivity at lower cost and still retain excellent product and service quality. Under these circumstances, the implementation of lean tool kaizen, improves the production environment with moderate investment. This case study carries evidence of genuine advantages when applying lean tools to the manufacturing shop floor. To be continued on page 44
