Advanced Materials Research Vol. 576

Abstract: Standing for long periods of time has been recognized as a potential contributor to muscle fatigue. When a person is performing activities in prolonged standing and wearing ineffective material of shoe insole, not only lead to muscle fatigue but can even cause injuries in the long term. The objective of this study is to determine the effects of two types of shoe insole materials; Ethylene Vinyl Acetate (EVA) and a combination of polyurethane (PU) and poron on muscle activity and foot pressure. The analysis of muscle fatigue was performed using surface electromyography (sEMG) while pressure under the foot was measured using FScan device. Results of comparison found that the two types of shoe insole materials showed significant difference (p-value < 0.05) in electromyography signals (µV) in the left and right gastrocnemius muscle while there are significant reductions on the peak pressure measured from the foot pressure measurement. It can be concluded that the combination of PU and poron is an effective material to be used a shoe insole for a person who is exposed to prolonged periods of standing.

Abstract: Assembly line balancing is assumed to have fixed task within specified task time during the initial stage of the mass production. The problem of current case study of this assembly line was the production line cannot meet the expected output plan with imbalance station cycle time. In this paper, productivity study and line balancing is applied to improve production line of GGMG & CALICO. The desired cycle time defined using the Standard Time Data (STD) which required the person to perform assign task till completion by defining the performance rating of person. The proposed solution proved by the implementation analysis conducted in the research. The results showed that the productivity of production line which is tremendously increased within 50% after implementation. There are six factors identified during the study which are bottleneck stations, workpiece flow, line layout, ergonomic, resource assignment and buffer allocation.

Abstract: Much has been reported in literature on virtual cell formation problems while a limited work is reported on worker assignments. Virtual Cellular Manufacturing Systems (VCMS) have come into existence, replacing traditional Cellular Manufacturing Systems (CMS), to meet highly dynamic production conditions in terms of demand, production lots, processing times, product mix and production sequences. Although the problem of worker assignment and flexibility in cell based manufacturing environments has been studied and analyzed in plenty using various heuristics/mathematical models, application of Artificial Neural Networks (ANN), adapted from the biological neural networks, is the recent development in this field exploiting the ability of ANN to work out mathematically-difficult-to-solve problems. In this attempt, the previous work of the author has been further developed and an attempt has been made to apply Learning Vector Quantization (LVQ) approach into worker assignment problems for higher order virtual cells i.e., three cells configurations and analyze the suitability of LVQ approach in terms of successful classification rate and simulation parameters for a number of VCMS periods.

Abstract: Demand forecasting is one of the most critical factors in production planning. The uncertain demand, which is the basic idea of planning the production level, nowadays is one of serious problems. The inaccurate demand forecasting could affect to excess production or shortage stocks which led to lost sales. Usually, the forecasted result is hard to represent real condition. Some studies already conducted related to fuzzy time series, each of them has its own advantages and disadvantages compared to other approaches. This research presents the combination of simple moving average forecasting and fuzzy logic model to demand forecast. Then, genetic algorithm (GA) is applied to optimize the mean square error (MSE) inside the fuzzy system. The MSE before and after GA optimization is 0,2192 and 0,1821, respectively.

Abstract: Material handling is one of major components in Flexible Manufacturing System (FMS). Any improvement of material handling capability is to affect the performance of the whole system. This paper discusses the simulation study on the effect of part arrival rate and dispatching rules to the average waiting time and production rate of the FMS. The facilities of the system were modeled into simulation environment by using Arena Simulation Software. The production parameters such as machine processing times, part transportation speed and type of products were put into the model to represent the behaviors of the real system. Two rules have been considered in the study, i. e. first come first served (FCFS), and shortest processing time (SPT). Average waiting time and productivity were taken into account as performance measures of the system. The result of the study showed that SPT rule gives shorter average waiting time and higher productivity. Based on this result, the SPT rules would be used to control part transporter in order to have a better performance of the FMS.

Abstract: The multiple routes travelling salesman problem (mrTSP) is an extension of the well-known travelling salesman problem (TSP), where there are several points clusters to be visited by salesman. The problem to be solved is how to define the best route in every cluster and initial position of each routes as interconnection points for the salesman. In this paper, modified genetic algorithm (mGA) is proposed in order to solve the mrTSP problem. In the proposed mGA, new heuristic algorithm for crossover and mutation operator based on local shortest path algorithm is proposed in order to assist the mGA to improve 'best solution so far'. Numerical examples are also given to test the performance of proposed mGA when solving mrTSP. The result of the study shows that the mGA is superior compared to conventional GA.

Abstract: This paper presents an analysis on the economic suitability of a large scale plant for the production of cellulase enzyme from Palm Oil Mill Effluent (POME). Based on the data and other relevant information gathered from indigenous operation of a lab and a pilot scale bio-reactors (30L and 300L capacities), a predicted evaluation of economic aspects of enzyme production with a 3000L bioreactor has been made. Factors such as the initial price and installation cost, the expenses for raw materials, operation and maintenance of the plant, overhead, utilities, logistics etc. were considered. Enzyme output from the proposed bioreactor was estimated depending on the optimum operational conditions established by the small scale investigation. Net present value (NPV) of the project was evaluated by using the discounted cash-flow analysis. With a conservative view of 5% escalation of recurring costs and a target of 70% capacity utilization an NPV of MYR 2,5 million was found to be achievable for a 10% discount rate and a plant life of 10 years,. Economic scenario developed for 50-100% range capacity utilization indicating the NPV can be helpful in making decisions for implementation of such plants. Thus production of cellulase enzyme from POME using a 3000L bioreactor is found to be economically attractive.

Abstract: To sustain in business by meeting the customer expectations with limited resources under tight schedule is a great challenge for high volume manufacturing industry. In this respect Value Stream Mapping (VSM) plays an important role as a strategic tool in streamlining the processing operations and enhances capacity utilization. This study has been conducted on application of VSM in a make-to-order metal stamping company engaged in production of different stamped parts of which the LCD TV frame is a significant one. Based on the product flow analysis, a current state VSM has been constructed using pertinent data collected from the production floor. Analysis of recorded videos and time studies were performed in order to figure out the scope of improvements in framing the future state map (FSM) in the context of cycle time reduction and line balancing efficiency. As observed from the FSM, the efficiency of production line is possible to be significantly increased from about 48% to more than 93% vis-à-vis a reduced batch completion cycle time. Thus it is obvious that with minor adjustments in the system in line with the findings of the study, the industry can make a substantial improvement in their operational efficiency.

Abstract: The study was conducted to investigate the level of implementation of lean manufacturing (LM) in Malaysian automotive industry. A number of survey methodologies were utilized to ensure reliability of the results of this study. Thirteen areas have been identified as typical workplaces implementing lean manufacturing. The study also investigated the benefits gained and obstacles faced by manufacturers in implementing the system. The frequency and tendency of applying lean tools in manufacturing environment have also been ranked.

Abstract: The research work focuses on sheet metal stamping process simulation of an automotive component known as bracket assembly upper spring made from low carbon steel and has axis-symmetrical cup shape that employs four multi-stage drawing processes. Non-value added drawing stages (optimization process) reduced and portrayed from the formability simulation result using finite element modeling (FEM) method. The modified design, with reduction of one draw stage, showed that the risk of the component to form cracks is lesser, the material elements are further away from the failure zone of the forming limit diagram (FLD) and it meets the requirement for minimum thickness. The FEM simulation was able to predict the formability and optimize the design of a sheet metal forming process that lowered the product cost and improve cycle time.