International Journal of Technical Research (IJTR) Vol. 5, Issue 1, Mar-Apr 2016

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1 Experimental Study For Assembly Line Balancing Using Largest Candidate Rule Algorithm In Automoblie Lighting Industries A Case Study Ankur Malik 1, Umed Khod 2 1 M.Tech, Scholar, 2 Assistant Prof. Department of Mechanical Engineering, Om Institute of Technology and Management, Hisar,Haryana,India 1 ankurmalik08@gmail.com, 2 umedkhod2007@gmail.com ABSTRACT:-Line balancing is an effective tool to improve the throughput of assembly line while reducing non-value-added activities, cycle time. LB is the problem of assigning operation to workstation along an assembly line, in such a way that assignment is optimal in some sense. This paper mainly focuses on improving overall efficiency of single model assembly line by reducing the non value added activities, cycle time and distribution of work load at each work station by line balancing. The methodology adopted includes calculation of cycle time of process, identifying the non value-added activities, calculating total work load on station and distribution of work load on each workstation by line balancing, in order to improve the efficiency of line. Key words: Line balancing (LB), Non value added activities (NVA), assembly line balancing (ALB) I. INTRODUCTION Quality product and capable to cope with customers demands are important aspects that should be take an account especially for small and medium industry. Management systems are also contributes in order to planning, controlling and measuring parameters related to the performance of the sectors. Companies should realize that the performance is depending on how well the production line in term of output. Line balancing primary focus is on minimizing waste related to over production, inventory, defects, transportation, motion, waiting. Assembly Line Balancing (ALB) is one way to achieve that. Principle of interchangeability and division of labour brought in the concept of assembly line, primary aim of the assembly line was to facilitate mass production, standardization, simplification and specialization. Besides this, assembly line was also useful in dividing complex work structures into number of elemental tasks, which would simplify the complexity of assembly work. ALB also provides flexibility to the employees, thereby reducing the monotonous activity thus improved job satisfaction for the employees. From the manufacturers point of view foremost advantage of ALB is the ability to keep direct labours busy doing productive work. Historically assembly line is designed for high volume production of single item or similar family of items II. LITERATURE REVIEW C Merengo, F Nava, A Pozzetti in their paper Balancing and sequencing manual single model assembly lines [1] In particular, it presents new balancing and production sequencing methodologies which pursue the following common goals, minimizing the rate of incomplete jobs (in paced lines and in moving lines) or the probability of blocking/starvation events (in un paced lines), reducing WIP. The balancing methodology also aims at minimizing the number of stations on the line; the sequencing technique also provides uniform parts usage, which is a typical goal in just in time production systems. O E Carcano, A Portioli-Staudacher, in their paper Integrating inspection-policy design in assembly-line balancing [2]. Different inspection policies yield different manufacturing, reworking, inspection, and external failure costs. While, in the literature, assembly-line balancing and inspection-policy design have usually been addressed as different problems, they are strongly interrelated. Inspection tests require time to be carried out, and sthus their assignation directly influences the results of the assembly-line balancing procedure, that is the number of stations that are necessary and hence the line installation cost. Thus, the advantages of integrating inspection policy design in assembly-line balancing are clear, but to our knowledge no such model is available yet. In this paper, a new model that simultaneously defines inspection policy and assembly-line balancing is presented. Peng Liu, Lang Li in their paper, The Application and Research of a Simulation-Based Line Balancing Method [3] paper applies a Line balancing method and the object oriented modelling technology. Firstly, the simulation. ISSN Page 63

2 Model of the box stream Line is set up and, the bottleneck is found out and analyzed with the model. Secondly, the rebuilt strategy based on the principles of ECRS (Eliminate, Combine, Rearrange, and Simple) and the theory of production Line balancing is given and evaluated by the model. Finally, comparing with the former production Line, implementation of the new strategy makes the production efficiency and quality improved greatly. Waldemar Grzechca in his paper, Cycle Time in Assembly Line Balancing Problem [4]assembly line balancing problem is discussed. Author focuses on cycle time. The importance of its value is shown. Different measures of final results of assembly line balance are presented. A numerical example is calculated. At the end remarks and final conclusions are given. M E Salveson in his paper, The assembly line balancing problem [5] assembly line balancing problem (ALBP) consists of assigning tasks to an ordered sequence of stations such that the precedence relations among the tasks are satisfied and some performance measure is optimized. In this survey paper we give an up-to-date review and discuss the development of the classification of the assembly line balancing problem (ALBP) which has attracted attention of researchers. S Ghosh, R J Gagnon in their paper, A comprehensive literature review and analysis of the design, balancing and scheduling of assembly systems [6] the results of a comprehensive review and analysis of the assembly line balancing literature. Quantitative developments and qualitative issues are addressed at both the strategic and tactical levels. The numerous quantitative and qualitative factors which the literature mentions could impact the design, balancing and scheduling of assembly systems are organized into an eight-level hierarchical, factor/decision taxonomy. This comprehensive taxonomy is used to assess our progress in assembly system design and operation. III. PROBLEM STATEMENT It was observed that the floor condition was in a haphazard situation. There were lots of in process inventories between the workstations hence its output was quite less. No precise work distribution was followed by the workers. Materials used to travel large distance from input receiving to cartooning. The line supervisors were not strict enough to control the quality right at the first time. So lots of reworks were there and the total completion time was delayed and the proportion of non value added time was increased. So, a smooth, streamlined and continuous flow is really necessary to avoid all such unexpected occurrence. OBJECTIVES The main goal of this study is to ascertain how lean manufacturing (LM) practices affect layout facility designing and line balancing. A severe case study was conducted specifically in the Lamp production section. At the very beginning a detailed work measurement of their existing Assembly line process and layout study was conducted. The paper addresses to solve the assembly line balancing with different labour skill levels to reduce in-process inventory and workload smoothing in the workstations of assembly with Housekeeping. CASE STUDY Table 1 shows the operations and time taken for the entire Lamp to produce. The line consists of 15 work stations. From the hourly production report, it was calculated that, for 8 hours production, the maximum production was 800pcs/day. So, the hourly output in assemnly line would be 80pcs. A schematic scenario of present assembly line section layout is given in the Table 1. Table: 1 present assembly line section layout Task Description Task Time (Min) Reflector inspection 0.17 Lens inspection 0.17 Hot melt robot 0.28 Lens pressing 0.28 Leak testing 0.3 Bulb holder spring 0.23 Bulb 0.35 Dust cap Vent tube 0.23 Full assy dust cap 0.23 Parking wire 0.54 U shape ventube 0.54 Photometric light testing 0.45 Final inspection 0.2 Packing 0.53 ISSN Page 64

3 A. Drawbacks in the current scenario:- Processes are not broken down properly. Inefficient use of manpower which is not uniformly distributed. High level of in-process inventory. Haphazard layout results huge amount of cross and back flows of Lamps. Low level of productivity than it should be with the existing level of resources. Housekeeping is not maintained properly. Finally the flow of Lamps from Assembly is not uniform as a result the ratio of online packaging is difficult to maintain. IV. METHODOLOGY Methodology adopted for line balancing as follows B. Line balancing Efficiency Line balancing Efficiency = (Total Station Line Time Cycle time x no. of workstations) X 100% Line balancing Efficiency (As-is) = 59.9% C. Largest Candidate Rule Algorithm (LCR) The main aim of the Line Balance is to distribute the total workload on the assembly line as evenly as possible, despite the reality in which it is impossible to obtain a perfect line balance among the workers. It is then the role of line balance efficiency which is related to the differences in minimum rational work element time and the precedence constraints between the elements. The Largest Candidate Rule (LCR) accounts for work elements to be arranged in a descending order (with reference to the station time and work elements) to each station value which is not exceeding the allowable preceded. Table 2 depicts the precedence relationship and immediate predecessor between these tasks. Table 2. Task Precedence Relations and Immediate Predecessors Task Description T T I. (Min) Predecessor(s) Reflector inspection Lens inspection Hot melt robot Fig.1 Flowchart for line balancing V. ASSEMBLY LINE BALANCING METHOD Assembly is a manufacturing process in which interchangeable parts are added in a sequential manner using certain material flow and design layouts. The line assembly is the efficient utilization of facilities with minimum material handling as well as easy production control. Since different workstations have different working capacity it is then important to apportionment the sequential work activities into workstations in order to achieve a high utilization of labour, equipments, and time. The Assembly Line Balancing in Assembly line assigns a given set of tasks to an ordered set of work stations and ensures that the precedence constraints are satisfied while the given performance measure is optimized. The line balancing process is performed first by calculating certain parameters such as the Customer Takt Time, Line balancing efficiency etc. A. Customer Takt Time Customer Takt time is defined as the ratio between the planned operating time per to the customer demand. Customer Takt Time = 36 seconds/piece (0.60 Min) Lens pressing Leak testing Bulb holder spring Bulb Dust cap Vent tube Full assy dust cap ,6 Parking wire U shape ventube Photometric light testing Final inspection ,12 Packing A task can be done by machines of different types and also by operators of different labor types. The processing time of any task is a variable determined by the skill level and efficiency of the operator. The work is divided in such a way that each operator gets equal ISSN Page 65

4 work load. The conceptual framework proposed and briefly summarized in the preceding section serves the purpose of demonstrating how the proposed framework would work. Table 3 depicts the work elements arranged according to stations. Then figure 1 shows the Operator line balancing chart after the line balancing process and the operator cycle times have been increased by providing the workers with extra operations and the idle times of the workers was reduced and to improve the productivity. Thus the operation in the line assembly which was handled by 15 workers is now reduced by 50 % to 8 workers. Line balancing Efficiency (To-be) = 85.5% Station 1 2 Task Assigned Task Description 2 Hot melt Robot 1 Application Reflector Inspection Task (Min) Lens Inspection Lens Pressing Leak Testing Fitment Bulb Fitment 0.23 Table 3 : Work elements arranged according to stations 9 Dust Cap Bulb Holder 10 venttube Dust Cap ventube full assy 11 Dust Cap and parking 12 Photometric wire Light Final Inspection Testing Packaging Finish Goods Bins 0.18 Fig. 2 Operator Line Balancing Chart (To-Be) Time The manufacturing line is redesigned to form a lean line with an optimum layout which results primarily in the productivity improvement. The area of the current layout was determined and the rearrangement of the machines in the layout so that there is a decrease in the area. The machines are kept in single straight line according to the operation sequence. The final Lamp from last operation is fully checked and corrected immediately for any defects. VI. FEATURES OF OUR LEAN SYSTEM Production time of the lamps has been reduced by 1.28 minutes; this has been achieved by combining operations with other operations. Operators and machines have been reduced to 8 & from 15. The numbers of operators are less than the number of operations (machines); one operator has to perform at least two operations. This will help to increase operator skill. Secondly, batch processing is converted into single piece movement by the implication of new layout. The rework level has been decreased over existing trends. The main reason for rework reduction is due to reduction in WIP and balanced work cells. Due to low inventory, mistakes are clearly visible and if any defect is found in the lamp, it will be cleared inline, and the piece comes out as a final product. Stations were labelled with a description of the process as well as pictures that detail each step. Lamps in feeding rack were sorted size wise, & the feeding was done size wise. VII. RESULTS & DISCUSSIONS Applying the new workstation design will improve the productivity significantly. In this study the lean manufacturing tools and techniques were studied and used. The problem of batch processing of existing is addressed by using single piece movement of WIP. Thus by converting long assembly line into work cells, the assumed worker multi-skilling seems effective as well as communication between operators is fast and accurate. The other benefits observed are the flexibility of rework reduction and online packing. As discussed above the Production time of the lamps has been reduced from 5.18 to 3.90 minutes. Operators have been reduced to 8 from 15. Assembly line efficiency has been increased from 59.5% to 85.5 %. Productivity per hour has been increased by 25 % through assembly line balancing. VIII. CONCLUSION The key outcome of this paper was the reduction in cycle time for single model assembly line, efficiency increases by reducing non value added activities, other outcomes were that assembly line balanced by recommending new layout. REFERENCES [1] C Merengo, F Nava, A Pozzetti Balancing and sequencing manual mixed-model assembly lines ISSN Page 66

5 International Journal of Production Research 37 (12) pp (1999). [2] E Carcano, A Portioli-Staudacher Integrating inspection-policy design in assembly-line balancing International Journal of Production Research 44 (18-19) pp (2006). [3] Peng Liu, Lang Li The Application and Research of a Simulation-Based Line Balancing Method pp ,(2011). [4] Waldemar Grzechca Cycle Time in Assembly Line Balancing Problem journal of industrial engineering, pp ,(2011). [5] M E Salveson The assembly line balancing problem Journal of Industrial Engineering Volume: 6, Issue: 3, pp ,(1995). [6] S Ghosh, R J Gagnon A comprehensive literature review and analysis of the design, balancing and scheduling of assembly systems International Journal of Production research 27(4), (1989). [7] A Otto, A Scholl (2011) Incorporating ergonomic risks into assembly line balancing European Journal of Operational Research 212 (2) pp ,(2011). [8] Subhash C Sarin, Erdal Erel A methodology for solving single-model, stochastic Assembly line balancing problem Volume: 27, Issue:5, pp , (2003). International Journal of Technical Research (IJTR) ISSN Page 67