Minimizing Makespan with Production Scheduling of Single Workstation Rework for Manufacturing Firm of Footwear

• Main Authors: CHANG, YUAN-CHEN, 張元榛
• Other Authors: LIU, YUNG-CHING
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/2w66pd

碩士 === 國立雲林科技大學 === 工業工程與管理系 === 105 === Shoe manufacturing industry belong to labor-intensive industry, which still mainly depends on semi mechanical processing nowadays since the introduction of automation is relatively slow. Take the case study company as example, the defective rate of sewing machine manufacturing procedures is from 8% to 10%. The wastes of materials and the losses of material costs could be decreased via rework approach that makes defective products into good products. However, workers on site may not be willing to choose rework approaches. If they do not want to rework, more materials would be needed to increase the production amounts, which increases the completion time. Even though workers are willing to rework, it is not uncommon to see that workers may set the defective products aside in the storage cache according to their rule of thumb, which may cause the inventory accumulation without good scheduling approaches of reworks. Therefore, this study considered the scheduling problems of flow shop for rework procedures in single stop to establish mathematics models taking advantage of genetic algorithm in hope of finding solutions for good scheduling approaches, which could minimize the maximal makespan in the manufacturing scheduling. Through case analyses, approaches of production amount without rework, launching rework scheduling once reaching 50% of total scheduled time (method 1), and launching rework scheduling once the defective rate reaching 50% (method 2) could be compared to understand the performances under varying rework stop numbers and defective rates. Finally, the optimal ratio between method 1 and method 2 to launch the sensibility analyses of rework scheduling was calculated to observe the alteration of completion time.