3.2 Value Stream Map (VSM) VSM helps an organization to identify the NVD activities of the observed production line. It is well established by research that VSM is the ideal tool to point out hidden causes for NVD activities. Rother and Shook considered the VSM as one of the most effective lean tools that is widely using to document, analyze and improve the flow of information and materials required to produce a product or service for the customers. In addition, VSM takes into account not only the activity of the product, but also the management and information systems that support the basic process. Basically, VSM helps to identify the flaws in production system that requires redesigning and to prioritize improvement. Gupta, et al. evaluated the VSM as an activity improvement technique to visualize an entire production process, representing information and material flow, to improve the production process by identifying waste and its sources. Throughout this study VSM of observed process line was developed at current and future state prior to depict the contribution of VSM implementation towards the bottleneck reduction. This study has been carried out as a case study in a litchi juice production plant with current state map and future state map after following the different steps starting from raw material to final product.
3.3 Present VSM
The current VSM of the litchi juice production line is constructed to point out the gaps that need to be removed to enhance performance indicators such as cycle time reduction, up time improvement, line balancing efficiency, etc. Throughout the present VSM the whole production system of litchi juice production line were depicted with the flow of order, raw materials, labor, information, VD and NVD times. It helps to draw the required production stage like syrup processing, homogenization & pasteurization, filing, warming, labeling and wrapping with mentioning required labor, cycle time (C/T), up time (U/T), change over (C/O) and batch size (2000 L). By observing the present scenario of regarding production line, it can be known like as what number of labor is needed at different production unit? How much VD & NVD time is present? Where & what kind of improvement should be done? It also helps to calculate the PCE, and Lead time. It was found that filer, labeler and wrapping machine were mainly responsible for down time (D/T). The D/T is the time that is wasted due to breakdown of machine; C/T- the time that is required to produce a single batch production; U/T- the time that is available for machine work or production. The filler machine’s cycle time was found 2880 sec, down time 657 sec, up time 77.19%; labeler machine’s cycle time was calculated 2940 sec, down time 665 sec, up time 77.38%; wrapping machine’s cycle time was found 3900 sec, down time 1074 sec and up time 74.46%. Filler machine speed was observed 245 bottles per minute (BPM); Labeler speed 240 BPM; Wrapping machine speed 30 case per min and each case contains 24 bottles; Batch size was 2000 liter and total labor were 36. The VD and NVD time were documented in Table-1. By this study, it was endeavored to increase the percentage of VD time by reducing the NVD time with the proper implementation of lean tools and six sigma methodologies.
3.5 Manufacturing waste of litchi juice production line The failure of many manufacturing companies to keeping them feasible in today’s manufacturing world has been criticized extensively on their futile effort to identify, reduce, and possibly eliminate wastes (muda in Japanese language) that are inherent in their manufacturing processes. In lean manufacturing world waste is defined as anything that destroys the resources and does not add any value to the customer requirement. According to Okpalaany activities or processes for which the customer is not willing to pay is considered as a waste that must be identified and eliminated. In addition, all NVD activities are known as waste in the lean manufacturing world. Womack and Jones defined the waste as any human activity which absorbs resources, but creates no value. Still now, seven types of waste were identified in the manufacturing and service sectors. Nevertheless, this list of waste has been modified and extended by the practitioners of lean manufacturing. The seven types of manufacturing wastes are overproduction, defect, waiting, unnecessary production, unnecessary inventory, unnecessary transportation between work sites, and unnecessary motion of labor in the work place. Based on the nature of production the manufacturing wastes are varied. In this study only defect, waiting and unnecessary motion wastes were observed most frequently. The Lean Enterprise Research Centre (LERC, 2004) at Cardiff Business School highlighted that for most production operations: 5% of activities add value; 35% are necessary non-value activities; 60% add no value at all. Therefore, there is no doubt that the elimination of waste represents a huge potential in terms of manufacturing improvements.
3.8 Motion waste of litchi juice production line The unnecessary labor movement in the production floor was considered as the motion waste. After the implementation of lean tools and six sigma methodologies in litchi juice production line it is expected that a number of unwanted labors could be eliminated that are documented. At present state, from Table-5, it is seen that 36 labors are engaged in the litchi juice production floor and it can be assumed after the implementation of lean tools and six sigma techniques the number of labor would be reduced to 22. It seems that a number of unwanted labors are engaged to manage the different types of bottlenecks and NVD activities.
3.9 Pareto analysis of litchi juice production line It is a statistical technique in decision making that is used for selection of a limited number of tasks that produce significant overall effect. It uses the Pareto principles – the idea that by doing 20% of work, 80% of the advantage of doing the entire job can be generated. According to David in any operation a large majority of problems (80%) are produced by a few key causes (20%). Therefore, by removing this 20% causes 80% problems can be removed from any production floor which is also known as "80/20 Rule". In this study, Pareto analysis was performed by drawing the Pareto chart consisting of causes for delay along the X axis and cumulative percentage of waiting or down time along the Y axis. The highest frequency of down time was found for bottle short in supply, while bottle queue in front of filer machine showed the lowest frequency. Different causes of down time with their frequency in terms of percentages and cumulative percentages were documented in Table-6. Pareto chart (Fig. 4) was depicted from Pareto table (Table-6) by aligning the different causes along with X axis; percentage and cumulative percentage of these causes for NVD activities were aligned along with the Y axis. From Pareto chart (Fig. 4) the most responsible causes are easily observed and therefore, effective initiatives can be taken to remove these causes. It is expected that if the most frequent first three or 20% causes like as insufficient bottle supply (39.80%), disarray of bottle at wrapping machine (20.09%), and sensor problem of machine (13.95%) could be removed the 80% NVD activities or down times could also be removed. 5S, JIT, and Kaizen strategies would be effective initiatives to remove these most frequent causes.