Process improvement through Lean-Kaizen using ...

The International Journal of Advanced Manufacturing Technology https://doi.org/10.1007/s00170-018-1684-8

ORIGINAL ARTICLE

Process improvement through Lean-Kaizen using value stream map: a case study in India Sunil Kumar 1

&

Ashwani Kumar Dhingra 1 & Bhim Singh 2

Received: 26 October 2016 / Accepted: 30 January 2018 # Springer-Verlag London Ltd., part of Springer Nature 2018

Abstract Lean-Kaizen is composed of two words lean and Kaizen; lean means elimination of non-value added activities (waste) and Kaizen means continuous improvement. Hence, Lean-Kaizen means continuous elimination of wastes through small-small improvements. This paper presents implementation of Lean-Kaizen concept in a small- and medium-scale enterprise (SME) at a non-capital region in India. The existing situation of the shop floor of selected SME was recorded, and current state map was prepared. The takt time was calculated, and bottlenecks were identified. Finally, a future state map was developed and gap areas were identified that served as a guide for determining the future lean activities. The “5-why” method was employed for identifying root causes in order to bridge the identified gap, and Kaizen events were proposed as solutions. In this study, two Kaizen events were proposed. In the first Kaizen event, the poka-yoke technique was used to control the variation caused by the slide of cylindrical grinding machine which eliminated wheel touch mark problem on the selected product. In the second Kaizen event, the brainstorming technique was applied to clamp the workpiece on the serration side rather than the slot side which eliminated the roughness on outer diameter. After the implementation of Kaizen events, reduced inventory level, reduced lead time and reduced cycle time, rework elimination, improved productivity, and improved product quality were achieved. It is concluded that Lean-Kaizen is an effective and reliable improvement technique which helps to tackle all types of inefficiencies hidden in the organizations. Keywords Lean-Kaizen . Value stream map . Lean manufacturing . Kaizen events . Small- and medium-scale enterprises

1 Introduction Indian small- and medium-scale enterprises (SMEs) are under consistent pressure from customers and competitors for producing quality products at the lowest cost. In the recent global competitive world, the customer expectations are higher in the * Sunil Kumar [email protected] Ashwani Kumar Dhingra [email protected] Bhim Singh [email protected] 1

Mechanical Engineering Department, University Institute of Engineering & Technology, Maharshi Dayanand University, Rohtak, Haryana 124001, India

2

Mechanical Engineering Department, School of Engineering & Technology, Sharda University, Greater Noida, Uttar Pradesh 201306, India

terms of quality and cost of the products. In order to meet these expectations, the manufacturers are working on adopting lean tools/technologies/principles/methodologies by implementing continuous improvement programs that minimize product cost, reduce delivery time, and improve quality of products [1, 2]. The SMEs are organizing an employee’s training to understand the concept of lean and lean principles for optimizing the product and process by eliminating waste to achieve competitive advantages. The on-job training of employees is also recommended which focuses on development of new concepts, skill and multi-skill building, problem-solving, learning about organizational changes, and other important factors [3]. The Japanese used such waste of elimination techniques more effectively since 1980s to achieve global competitiveness, which demonstrated a greater commitment to the philosophy of continuous improvement than other countries [4, 5]. Lean-Kaizen is a relatively novel concept and becomes unknown to employees in most of the Indian organizations. It is a straightforward improvement technique that assists in

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eliminating different inefficiencies in the organizations [6]. It is composed of two words that is Lean and Kaizen, lean means elimination of non-value added activities and Kaizen means continuous improvement [7]. Hence, Lean-Kaizen means continuous elimination of wastes through small-small improvements. Kaizen is a popular technique that applies to eliminate wastes at all levels of any organization [8, 9]. It follows an umbrella concept which focuses on the process improvement by eliminating wastes in process; thus, it provides base for lean manufacturing (LM) that directed towards achievement of continuous improvement [10]. It is referred as the key building block of lean thinking [11]. Henry Ford first understood and described many of the concepts of what is today known as LM and Kaizen. He observed that standardization and innovation as two sides of the same coin. He applied LM and Kaizen principles at every opportunity, seeking constantly to reduce waste, variations, system cycle times, and improved overall performance [12]. However, the main objective of Lean-Kaizen is the simultaneous achievement of excellence in quality, cost, and delivery; it provides a better understanding for every individual of the organization to participate in achieving goals of the organization for achieving continuous improvements [13-15]. Many lean tools and techniques including visual control, poka-yoke, value stream mapping (VSM), cellular manufacturing, standardization of work, visual, quick change over, pull system, and kanban called as lean building block [13] have been used for eliminating wastes in manufacturing processes. Few other studies of successful lean implementation were also recorded in the literature in context to Indian SMEs. Through this study, an attempt has been made to implement the Lean-Kaizen concept using value stream mapping in order to tackle all types of inefficiencies and waste present in process and procedures of the selected SME. The study demonstrates the identification and implementation of Kaizen events and its associated benefits. This study helps the managers and practitioners to identify waste hidden in the procedures and processes of their organization. Further, the study demonstrates a road map to tackle the various wastes.

2 Literature review 2.1 Lean manufacturing and Kaizen practices LM is a program that focuses on increasing operational efficiency, reduce costs, and reconfigure processes [16-19]. It offers shorter cycle time and lead time, lower work in process (WIP) and costs, higher quality and revenue, increased production and profit, and better customer services [20, 21]. Lean principles (waste elimination, pull production, zero defects, streamlining of processes, quality at the source, and

continuous improvement) have been accepted and applied by many production or operation managers across many disciplines. The LM implementation success mainly depends on employee participation, proper skills and training, and top management commitment [22]. The fundamental aim of Kaizen is to improve operations [23]. The various studies in many countries have proved that Kaizen has progressively been accepted worldwide and can combine various waste elimination tools and techniques easily and effectively [6]. Kumar and Harms [24] stated that continuous improvement can be achieved through process mapping to visualize wastes and ultimately trigger Kaizen blitz activities. Bateman [25] notified that Lean-Kaizen implementation is the way of improving the performance in internal and external quality of service processes. Bhuiyan and Baghel [26] illustrated that continuous improvement program helps in identifying and eliminating wastes in the production line and improves the quality of product. Brunet and New [27] conducted empirical study on Kaizen and concluded that Kaizen evolves uniquely within each organization. Van Scyoc [28] evaluated various quality improvement tools and techniques such as Kaizen and poke-yoke to improve both the leadership in process safety and the performance of a fieldwork team. He explored how methods are applied for improving product quality to attain continual improvement with process safety. Barraza [14] illustrated that three techniques namely 5S, Gemba Kaizen workshops, and process mapping which are related to Lean-Kaizen have a direct effect on the processes and management systems. Singh et al. [29] applied fuzzy TOPSIS to develop an index that measured the leanness of an Indian automobile industry by assessing supplier issues, customer issues, investment priorities, and lean practices within an organization. They stated that these techniques improved the processes and quality of public services. Glover et al. [30] notified that sustaining results of a Kaizen event is difficult over time for many organizations. They identified the factors which prominently affect sustainability of work area employee attitudes and commitment organization. Karim and Arif-Uz-Zaman [31] proposed a methodology which enables systematic identification of manufacturing wastes, select appropriate lean tools, identify relevant performance indicators, achieve significant performance improvement, and establish lean culture within the organization. Dibia et al. [32] developed a social technical model named as lean “Leadership People Process Outcome” and measured benefits as waste elimination and process optimization that drive the industry towards continuous improvements. Arya and Choudhary [12] notified that lean approach-based practices improve production efficiency and product quality. Stadnicka and Ratnayake [33] explored the advantage of lean tool implementation in the plain old telephone service industry.

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2.2 Value stream map practices Singh and Sharma [15] conducted a case study in crankshaft gear manufacturing process and bridged the gap between current and future state of manufacturing organization and finally concluded that VSM is a dominant tool that helps an organization to improve the understanding towards lean. Chen et al. [34] implemented VSM in a fabrication process of an SME and identified process improvement opportunities by drawing current and future state map of the existing processes. The study proposed Kaizen events to bridge the gap between current and future state of the fabrication process and after applying Taguchi experiment design and rabbit chasing techniques, the study witnessed the reduction in variation of plasma cutting process, reduction in inventory levels, and improvement in the system flexibility of the organization. Singh et al. [7] applied VSM to identify wastes such as WIP, lead time, and manpower by bridging the gap between current state and future state of a production industry. Singh et al. [10] concluded that VSM is valuable practice for identification and elimination of various wastes. VSM, a lean manufacturing technique, is dissimilar than orthodox techniques and enfolds both value added and nonvalue added activities. Julia et al. [35] investigated the core complications and limitations encountered during the preparation of current state maps, analysis of the associated roots, and indicating procedures that facilitate the effective use of VSM to map processes. Ramesh and Kodali [36] proposed a decision framework for accurate selection of VSM tools based on organization priorities. The study concluded that VSM can reduce all system wastes, minimize resources and optimize organizational performance level. Vinodh et al. [37] eliminated wastes by applying VSM using 5S in the investigation conducted in a cam shaft manufacturing steering system of automobiles, and the study explored that VSM can eliminate wastes. Dorota [38] applied VSM with Kaizen for further reduction in product lead time and to improve the safety of the workplace in a smallscale bench vice manufacturing organization. Prashar [6] employed the Lean-Kaizen approach using VSM for process improvement through redesigning an assembly line in a manufacturing steering system of automobiles. VSM simplifies lean implementation track by detecting gap areas in the organization [7]. Vinodh et al. [39] highlighted that VSM is a significant lean manufacturing technique that emphasis on the micro-analysis of a manufacturing process. KR et al. [24] discussed the importance of VSM by mapping the current state and the future state of a manufacturing organization and concluded that VSM and Kaizen are effective tools to identify and eliminating wastes in the process. Ciarapica et al. [40] proposed VSM as proactive approach to choose the best technological approach at the commencement of the project. The recent literature work on VSM is discussed in Table 1.

2.3 Implementation barriers of lean manufacturing and Kaizen The issues in implementation of lean may vary from country to country, geographic location within the country, and work culture of the organization [46]. The improper processing practice, unorganized structure, and communication gap lead to surge several losses and wastes within organization which ultimately turn the organization ineffective [47]. Since waste elimination and zero defects are prime objectives of LM which can be achieved by spreading awareness of lean, identify lean drivers, removing lean barriers, developing better organizational culture by effective leadership, preparing cross functional teams, suggestion scheme, paying rewards and appreciation to worker, adopt innovations, and efficient information system through proper understanding of lean principles [48, 49]. Carmignani and Francesco [50] developed a framework to highlight critical issues that may limit the adoption of lean in the luxury-fashion market. The lean implementation depends upon application of appropriate tools and techniques, top management, and worker interactions [46]. After the implementation of LM, the entire system and various processes of the organization are reviewed to grab continuous improvement opportunities. In today’s industrial world, systematic procedure for lean implementation is still absent [51]. In addition, the selection of proper lean strategy depends upon common judgment rather than logical justification made by the organization [3]. Due to lack of understanding of lean, Indian SMEs are still deprived of many lean benefits. After having gone through the extant literature, a systematic procedure of Lean-Kaizen implementation using value stream map is demonstrated through a case study which helped the selected SME to improve its processes for achieving competitive advantage and sustainable growth.

3 Case study 3.1 Manufacturing organization profile XYZ Enterprises, a small- and medium-scale manufacturing organization located at a non-capital region in India, is a manufacturer of automobile parts such as a spindle kick starter (SKS—shown in Fig. 1) used as spindle for kick assembly in bikes. This company has approximately 150 employees working in two shifts of 8-h duration each. It owes its success to its LM operations at each manufacturing step.

3.2 Present work In the present work, a case study was performed by applying Lean-Kaizen concept using the VSM tool in the selected company. Keeping in view the lean principles given by [52-54],

Int J Adv Manuf Technol Table 1

Recent contribution in the VSM literature

Author/year

Method used/study

Target reduction/improvement Area of application/ product name/location

Original contribution/conclusion

Dotoli et al. (2011) [41]

VSM integrated with AHP

Internal logistics improvement Manufacturer of forklift trucks, Beri (Italy)

Proposed integrated framework to detect the critical worries of processes and evaluated them to identify the most suitable deeds that help to realize the desired improvement. Proposed VSM-based simulation framework which is used to evaluate two basic lean distribution practices such as pull replenishment and class-based storage policy.

Reduced cycle time, increased Tire distribution company in Ireland the throughput rate, decreased the number of lateness jobs, reduced inventory level, enhanced labors, and equipment utilization Cost reduction Automobile supplier firm, Developed integrated framework to Tabanli and Ertay VSM integrated with assess the created value and the shoulder belt grabber (2013) [43] RFID (radio frequency relevant benefits within the production system identification process of the organization. technology)-based electronic Kanban system Sabaghi et al. (2015) VSM, simulation, Reduction in lead time and Plastic manufacturer in Iran Proposed framework to evaluate the [44] kanban, JIT, ANOVA WIP inventory basic performance measures and analyze the system configurations.

Mahfouz and Arisha (2013) [42]

Integrating simulation with VSM

Vinodh et al. (2016) [45]

VSM integrated with life-cycle assessment (LCA)

Reduced environmental impacts such as water eutrophication, carbon footprint, air acidification, and total energy consumption

Automotive component manufacturing organization, Tamil Nadu, India

Proposed framework which is capable of envisaging and measuring manufacturing sustainable performance of process performance.

the value stream mapping is done with pencil and paper by using a well-defined set of icons. The process symbols are used to draw information and material flow in the production line of the case product.

requirements of product, movement of product, and WIP/inventory were also recorded. The collected data was analyzed, and high rework, rejection rate, and inventory of the product were noticed in the process.

3.3 Data collection

3.4 Current state map

The data was collected by taking personal visits to the company over a period of 15 days. The data pertaining to cycle time (CT), change over time (C/O), numbers of shifts, numbers of workers, lead time, and value added time was recorded. In addition, the monthly/daily

Current state map provides a pictorial view of existing processes and guides to identify gap areas for improvement. The current state may be drawn while conducting this case study is shown in Fig. 2. As showing, upstream flow for supplier and downstream flow for customer linked with shipment department. The upstream flow is given at the top which represents information flow that moves from right to left between customer and supplier. The downstream flow is given at the bottom which represents the material flow that moves from left to right in the production line. Ten processes namely Cutting-P1, Spline Deburring-P2, Face and Centering-P3, CNC Turning 1st Half Side-P4, CNC Turning 2nd Half Side-P5, Slot Milling-P6, Shot Blasting-P7, Grinding-P8, Plating-P9, and Final Inspection-P10 were involved in the product line. The raw material is ordered monthly and shipment reaches every week; thus, the inventory level of raw material is observed as

Fig. 1 Spindle kick starter in snap gauge

Int J Adv Manuf Technol Monthly Forecast

XYZ Industries

Annual Forecast & Monthly Schedule

PPC Department

Daily Requirements

Weekly Schedule

Customer

Shop Floor Supervisor (Weekly Schedule)

Supplier

- 14,625 per/ month

1000 Kgs Rods, 16mm (Diameter)

Tray = 50 pieces 2 Shifts

Daily Schedule

Weekly Daily

I

P1

15

I

P2

110

CT = 32s C/O = 3600s 2- Shifts 85% uptime

CT = 5s C/O = 0s 2- Shifts 100% uptime 1

1 15 days 32sec

51sec

P4

I

I 242

365

CT = 45s C/O = 600s 2- Shifts 100% uptime 1

0.042 days

0.088 days 5sec

P3

I 435

CT = 55s C/O = 1200s 2- Shifts 100% uptime 1

0.055 days 55sec

58sec

P5

P6

I

I

P7

210

351 CT = 58s C/O = 1500s 2- Shifts 100% uptime 1

CT = 60s C/O = 900s 2- Shifts 100% uptime 1

0.073 days

0.690 days

60sec

P8

I 850

P9

250

CT = 62s C/O = 1260s 2- Shifts 100% uptime 1

CT = 90s C/O = 1740s 2- Shifts 80% uptime 1

1.687 days 62sec

I

I

P10

Shipping

220 CT = 65s C/O = 1180s 2- Shifts 100% uptime 1

Production Lead Time 18.016 days

0.381 days

90sec

65sec

Value Added Time 473sec

Fig. 2 Current state map

15 days which makes lead time longer. Additionally, the engineering and production planning and control (PPC) department is scheduling on weekly basis to each process separately via work orders and is receiving status of produced quantity of the product from shop floor supervisor. A communication gap is observed between the individual workstations. However, the entire production system follows push mechanism. Many work areas with WIP exist for a long time. The production lead time and value added time were calculated as 18.016 days and 473 s, respectively. Also, these times are shown by a timeline presented at the bottom of the current map. The cycle time for each process is the average cycle time determined from the actual data collected. The process P8 was reported for high cycle time that is 90 s caused by an increased rejection rate and rework. This process was a bottleneck process with high WIP. The inventory storage points are denoted by the triangles between the processes.

3.5 Takt time calculation Under this study, a few assumptions were made in which operation skills and shift-wise variations were not taken into consideration for calculations. The company is operating on

two shifts of 8 h duration every day with an average customer demand of workpiece of 14,625 pieces per month. The number of effective days in a month is 25 days by excluding four Sundays and one holiday. Thus, the customer demand per day was found to be 585 pieces. Since the average number of working hours per shift is 7 h by excluding two lunch breaks of 30 min and two tea break of 15 min for each shift, the available working time per day was calculated as 50,400 s. The takt time calculation is shown as follows: Takt time ¼ available working time per day in seconds= customer demand per day in pieces ¼ 50; 400=585 ¼ 86 seconds per piece

The calculated takt time indicates that the selected SME is required to produce one workpiece in every 86 s to meet the customer demand. So, the production facilities should be optimized in such a way to meet the calculated takt time.

3.6 Future state map On the basis of information collected in the current state map, non-value added activities within the system were identified. As the goal of lean is to reduce or eliminate wastes, a future state is developed that serves as a guide for all future lean activities. Using the eight steps [52], the future state map

Int J Adv Manuf Technol XYZ Industries

Monthly Forecast

Supplier Loop

Annual Forecast & Monthly Schedule

PPC Department

Daily Requirements

Weekly Schedule

Bajaj Auto

Supplier

- 14,625 per/ month Bar

5000 Kgs Rods, 16mm

Tray = 50 pieces Daily Order

2-Shifts Bar

Daily (Milk Run)

Loop II OXOX Loop I

Daily

50

50

50 50

Batch 210 blanks /day

P3+P4+P5+P6+P7+P8+P9+P10 Production Cell

Shipping

P1 + P2 Stage

CT = 37sec C/O = 60 min 2- Shifts 85% uptime 1

Eliminate Wheel Touch Problem

Target 5 operator

Takt = 86sec CT = 80sec C/O = 0 2- Shifts 100% uptime

Eliminate Outer Diameter

Work Content to 80sec

Production Lead Time 5.5 days

2 day

1.5 days

2 days 37sec

Value Added Time 117sec

80sec

Fig. 3 Future state map

4 Steps to develop future state map 4.1 Determine the requirement of finished goods supermarket or supply directly to the shipment The customer demand varies unpredictably, and the selected SME is not certain about the future requirement of the finished product. Thus, the industry decides to start a supermarket carrying a 2-day inventory of finished goods that can possibly ship to fulfill customer demand in future. Since the customer demand is in multiple of 50 pieces per tray, the kanban size is selected as 50. This means that each 50-piece tray in finished goods supermarket will generate one production kanban. As the shipping department withdraws trays from this supermarket for delivery to customer, the production

kanban for those trays will be sent back to production line to produce another 50 pieces.

4.2 Develop possibilities of continuous flow process Continuous flow refers to one-piece flow. After analyzing, the current cycle time of each process in current state map as shown in Figs. 2 and 4, the following observations have been made. & The cycle time of process P2 is very short and far away from takt time; thus, there is no possibility to fix into the production cell. The process P2 has no changeover time

Cycle Time (seconds)

shown in Fig. 3 was prepared by implementing all proposed changes in current state map that identify wastes. The continuous flow processing and supermarket pull system are introduced to control the production at workstations. The signal, production, and withdrawal kanban are used for systematic and effective movement of material between the workplaces.

100 90 80 70 60 50 40 30 20 10 0

Takt Time= 86 seconds 60

62

P5 P6 Processes

P7

58

55

90

65

45 32 5 P1

P2

P3

P4

Cycle time (sec)

P8

Takt time (sec)

Fig. 4 Summary of current cycle time and takt time

P9

100 90 80 70 60 50 40 30 20 10 0

Cycle Time (seconds)

Int J Adv Manuf Technol 100 90 80 70 60 50 40 30 20 10 0

Takt Time = 86 seconds 16

29

34

54

5

P1+P2

60

51

32

46

44

P7+P8

P9

26 P3+P4

4 P4+P5 P5+P6+P7 Processes

Fig. 5 Production cell cycle time after continuous flow processing

&

&

and is performed near to the process P1, so can be easily combined to process P1. The processes like P3, P4, P5, P6, P7, and P9 have cycle time less than the takt time, and the cycle time for process P8 is more than the takt time, so the cycle time of grinding process should be reduced by identifying possibilities of continuous flow processing. These can develop a continuous flow as shown in Fig. 5, and thus, all these processes are shifted into a one cell named “Production Cell” [52]. The possibility of incorporating process P1 and P2 into continuous flow with the rest of the processes means slowing down total cycle time of the entire production system. It makes more sense to run processes P1 and P2 as a batch operation and controls its production with a supermarket-based pull system.

The total cycle time divided by takt time shows that six operators will be needed to perform these processes in continuous flow.

4.3 Identify supermarket pull mechanism Presently, the selected SME uses push mechanism which accumulates inventory between the individual workstations. The industry orders for raw material in the forms of bars on a monthly basis to the supplier and shipment reach every week at store by road. The current situation generates two kinds of potential problems: high inventory level of raw material and possibility of no raw material for production. To remove these problems, one supermarket of 2 days for raw material is installed within the system which informs the production manager not only the availability of raw material but also the production schedule for blanks: standard size parts on which operations to be performed. However, the supplier was not convinced to receive kanban, the selected SME attaches an internal kanban to receive raw material and sent these kanban to PPC department whenever raw material is delivered by the supplier. Additionally, following the milk run delivery system to collect raw material from different suppliers on a daily basis eliminated 85% of the raw material

inventory. The third supermarket of 1.5 days of produced a blank after process P2 is essential to set up to meet production cell minimum requirement of approximately 210 blanks per day. The time specified is provided for giving allowance to certain cutting and deburring machine problems. In the blank piece supermarket, withdrawal and signal kanban are used to transfer the material in a systematic manner and are drawn by dotted line on future state map.

4.4 Identify the single point for scheduling (the pacemaker process) in the production chain Thus, the single scheduling point is clearly the production cell. At this point, the implemented pull mechanism moves the material from production cell to finished goods supermarket where the product will be withdrawn and staged for shipment. Since all downstream processes occur in a flow, the production cell is displayed as the pacemaker.

4.5 Determine the level of product mix at pacemaker From the lean perspective in the value stream, batching is not desirable because it boosts inventory level and extends the lead time. Also, tracking quality problems is much difficult in batching. The production control would send customer order to the daily shipment where all the corresponding trays of the finished goods supermarket will be out at once and will be staged for shipment. In the production cell, the production mix will be leveled by installing the load-leveling box (Fig. 3) which uses a stack of production kanban with each kanban corresponding to a tray of 50 pieces.

4.6 Determine the natural increment of material at pacemaker process In order to supply the finished product to the customer, the company uses trays to convey the material in which each tray carries 50 pieces which is standard tray size for delivery. Thus, the pitch or natural increment is calculated as Pitch ¼ takt time  tray size ¼ 86 seconds=pieces 50 pieces=tray ¼ 4300 seconds=tray This means that for every 4300 s, a tray of 50 pieces will be moved from one process to the next process corresponding to the respective production and withdrawal kanban. The pace of increment of material will be controlled by load-leveling box installed over the production cell. Each column of the loadleveling box denotes a pitch increment in each shift. The operator can retrieve a new tray of 50 pieces as a production order for processing after the end of pitch increment.

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PERATO ANALYSIS GRAPH OF SKS 1200

120.0

1000

899

90.2

95.3

99.5

98.9

97.7

100.0

100.0 100.0

QTY.

800

80.0

600

60.0 47.8

400

40.0

200

108

51

20.0 25

13

9

0 STEPS ON OUTER DIAMETER

WHEEL TOUCH/ MARK

DAMAGE / DENT

DIAMETER U/SIZE

COMM. %AGE

1013

WRONG PART SUPPLIED DEFECT NAME

LENGTH U/SIZE

1

0.0

SERRATION OPERATION DAMAGED MISSING

Fig. 6 Pareto diagram

4.7 Identity the process improvement to realize future state Out of seven deadly wastes [54], two wastes were identified in the production line namely defects and inventory which are essential to be removed or eliminated from the existing process in order to achieve the future state. These identified wastes are also verified from collected data by monitoring the in-process quality status records. Subsequently, the Pareto diagram shown in Fig. 6 was drawn. Based on defect-wise table and Pareto diagram, two major quality problems such as wheel touch mark and steps on the outer diameter (OD) of workpiece were found to highly contribute towards the rejection rate which ultimately increased the inventory level at process P8. These problems demand extra time to rework the non-conformities of product. In order to achieve material and information flow in the present value stream, the company requires the following process improvements. & &

Eliminate quality problem highlighted as wheel touch/ wheel mark at process P8 Eliminate quality problem arises as steps on OD at process P8

produce surface finish on the shank of the product. The process requires active supervision by the operator. The process is done by clamping the product from both sides on machine. One side of the clamping is connected to head stock while the other side is connected to the tail stock of the CG machine with the fixture or bush mounted on the slot side to the head stock end. This arrangement is shown in Fig. 7. Root cause analysis In order to assist the Kaizen events, the “5-why” method [54] was used to identify root cause of each problem existed in the current state map. The steps followed as shown in Table 2. As shown, the “fifth why” revealed the root cause of the selected problem that is needed to be fixed with a permanent feasible solution. In this case study, two Kaizen events were identified. In the first Kaizen event, the poka-yoke technique [55] was used to fix the uneven gap between wheel face and workpiece face after each wheel dressing which controls the variation caused by the CG machine’s slides and ultimately eliminate wheel dash mark problem of the selected product. In the second Kaizen event, the brainstorming technique [56] was applied to collect suggestions for fixing the variation in slot width caused by clamping the workpiece on the serration side by bush.

4.8 Selected process at glance and proposed Kaizen

4.9 Performing Kaizen event

The purpose of implementing Lean-Kaizen concept is to identify wastes and eliminate root causes which generate wastes. The future state map provides a pictorial view of ideal processing in future which acts as guide to direct the changes in the current status of the organization. The conversion from current state to future state may reveal many Kaizen events based on various requirements that arise during transition to future conditions. In this study, two Kaizen events (to be implemented at process P8) were selected to realize the future state.

The proposed Kaizen events were performed by taking actions on root causes of the selected problems.

Process description The process P8 is grinding process performed at cylindrical grinding (CG) machine and is used to

4.9.1 Kaizen event 1: eliminating quality problem highlighted as the wheel touch mark at P8 through poka-yoke In order to eliminate wheel touch mark in the present case, the uneven gap was measured by using Vernier Caliper (digital, least count 0.001 mm) between wheel face and workpiece face after wheel dressing performed by the operator. Then, a dial indicator was recommended for the installation on the machine wheel slide of the CG machine (Fig. 3) that displays reading of

Int J Adv Manuf Technol Fig. 7 CG machine slide position (at rest) after wheel dressing before and after VSM implementation

wheel slide position at rest. Each shift operator at P8 was asked to note down the reading of the wheel slide from the dial indicator initially after a wheel change that should be fixed after each wheel dressing. The setting time of positioning wheel for dressing would be reduced for each wheel dressing. The dial indicator should be synchronized with the control panel of machine. The machine would be stopped if it crosses the set limit on dial indicator while grinding the product. Implementation The dial indicator was fixed on a machine slide to eliminate wheel touch/wheel mark problem. In the current situation, the running workpiece (last one or two before wheel dressing) of the selected product inspected at the workstation (P8) by the author for a time period of 8 h and found three pieces faced quality rejection (defective) due to wheel touch problem. No criteria for the position wheel for dressing were set by the operator after each wheel dressing. This problem was resolved by fixing a dial indicator (0-10 mm, least count 0.001 mm) on the machine wheel slides (Fig. 7) that positioned the wheel

Table 2

for dressing and controlled the variation produced during the dressing wheel as well as grinding process (P8). Then, wheel dressing setting time was reduced from 41 to 14 s. The knob of the dial indicator was synchronized with a control penal to limit the longitudinal motion of the wheel slide on the CG machine. Additionally, the frequency of wheel dressing for grinding operation was not fixed by anyone. It was executed on the basis of operator decision only when defective parts were produced. Then, wheel dressing frequency was fixed to 1100 pieces based on the collected data. 4.9.2 Kaizen event 2: eliminating quality problem highlighted as steps on OD at P8 through brainstorming A meeting of four to six team members was called to perform a brainstorming session in which team members were asked to provide suggestions for eliminating steps on OD problem on plain papers. Many suggestions were presented, and each suggestion was further discussed by the team members to identify

“5 Why” method for identifying root cause of selected problems

5 Why technique

Problem 1: wheel touch/wheel mark

Problem 2: steps on OD

Why 1

Wheel touch (mark) created due to uneven gap between grinding wheel face and component face. Uneven gap arises, because the operator sets the gap between grinding wheel face and workpiece face manually and by his own judgment after each wheel dressing. Because no facility of auto adjustment of this gap is provided on machine.

Steps arise due to clamping the workpiece on the slot side. While clamping the workpiece, slot width variation is observed.

Why 2

Why 3

Why 4 Why 5 Root cause

The machine is old enough and no idea of this kind of problem (on that time) could be imagined. No facility on machine to measure this gap. No facility provided on machine for measuring gap between grinding wheel face and workpiece face after wheel dressing.

Measured and verified the slot width of a sample of ten workpieces as per drawing standard of SKS at P8. Each workpiece suffered from slot width variation. Variation in slot width. Due to variation in slot width.

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feasible solution of the selected problem. The suggestion of clamping the workpiece on the serration side was selected as the solution, and this solution was recommended to be implemented on the CG machine (by consensus decision). A target was set to all team members to finish implementation task. Implementation In this situation, all the operational activities including clamping the workpiece for grinding operation at P8 were physically verified by the author and found that wheel touch (mark) presently contributing in house rejection of selected SME. This problem was fixed by clamping the workpiece on the serration side (by bush as shown in Fig. 8) rather than clamping the workpiece on the slot side to eliminate problem of wheel touch mark on the product. The place of clamping bush on workpiece was shifted towards the serration side from the slot side for better gripping and positioning caused minimum vibration on product which ultimately eliminated steps on OD problem. Clamping bush for the serration side is recommended to be replaced with a new bush after every production of 25,000 pieces. Besides implementing these Kaizen events, electronic information and Kanban system (as stated earlier while developing future state) were implemented to minimize the inventory level of this company.

4.10 Analyzing the results The results were analyzed by referring to the data obtained from before and after VSM implementation to measure the effectiveness of the Lean-Kaizen concept. Some tangible and intangible benefits of lean implementation were observed in the form of elimination of rejection rate and rework, improvement in productivity, and quality of the product. Lean improvements The proposed Kaizen events were applied within a period of 45 days, and the following benefits could be realized in this company. Fig. 8 Clamping of work piece on the CG machine before and after VSM implementation

Improvements in the quality of the selected product. No rejection was reported in each shift due to wheel touch mark and steps on outer diameter problems for a test period of 20 days. The rejection cost calculation was made as under Total number of rejections or defectives observed=month ¼ 1912

Total numbers of rejected part turned to scrap by wheel marks and steps on OD=month ¼ 272 Total numbers of rejected part turned to scrap=year ¼ 272  12 ¼ 3264 Price of the product per piece ¼ 72 INR ðIndian National RupeesÞ The total rejection cost of the product due to poor quality per year ¼ 3264  72 ¼ 2; 35; 008 INR

Thus, the process saved rejection cost of 2.35 lacs INR per year due to poor quality and attained zero customer complaints and zero in-house rejection quantity as shown in Fig. 9. The production became smooth along with ease in working conditions. The benefits achieved are presented in Table 3.

4.11 Discussion Many organizations have used various lean tools and techniques such as Just in Time, setup reduction, 5S, and TPM for becoming lean and reported significant benefits [2, 14, 37]. However, it is obvious that there is a need to understand the entire system in order to achieve maximum benefits. In this research work, an endeavor has been made to discuss implementation of the Lean-Kaizen concept using the VSM tool in the selected SME. Two Kaizen events were proposed to bridge the gap between current state and future state of the case study organization. The data collected after Lean-Kaizen implementation reported significant reduction in rework, inventory level, lead time, non-value added time, setup time, and ultimately improved productivity and quality of the product. In addition, the communication has become simplified so that quality problems can be easily traced within the system. The study

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References 1. 2.

3.

4. Fig. 9 Setting time and rejection quantity before and after VSM implementation

showed that Lean-Kaizen using VSM tool is an effective and reliable improvement technique which helps to tackle all types of inefficiencies in organizations. This method can be applied to all kinds of products, procedures, and processes to achieve improvements in system, process, or procedure.

5.

6.

7.

8.

5 Conclusion After having gone through the extant literature, it is observed that the lack of understanding of lean in Indian SMEs is still deprived of many lean benefits. A few studies of successful lean implementation were recorded in the literature in context to Indian organizations. This case study is an attempt to implement the Lean-Kaizen concept using value stream mapping in order to tackle all types of inefficiencies and wastes that existed in processes and procedures of the selected company. The study demonstrates a road map to tackle the various wastes. The results of case study conducted in Indian manufacturing industry demonstrate the effective way to identify and eliminate waste. The study reported benefits such as reduction in machine setting time by 65.85%, manpower by 40%, production lead time by 69.47%, and value added time by 75.25% which smooth production and ease working condition of the industry. The case study can help the managers and the practitioners in order to identify wastes in the procedures and processes of their organization. Further comparison with other waste elimination technique and cost-benefit analysis of future state map can be made.

9.

10.

11.

12.

13. 14.

15.

16. Table 3 VSM

Benefits after implementing the Lean-Kaizen concept with 17.

Criteria

Value reduction

Percentage reduction

Setting time for wheel dressing Manpower requirement Production lead time value added time

27 s

65.85%

From 10 to 6 workers From 18.016 days to 5.5 days From 473 s to 117 s

40% 69.47% 75.25%

18.

19.

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