Comparison of Five Alternative Manufacturing Strategies For increasing Job Shop Capacity and Their Impact on Manufacturing Performance

Managing job shop manufacturing is quite different compared to other manufacturing systems due to its dynamic changes in process routings, cycle times and fluctuations in demand. Managers in job shops face problems in attaining optimum performance of the job shops. These can lead to failure to meet due dates, low machine level utilization and high level of work-in-progress (WIP). These problems can be exacerbated when management has to consider reacting to increased demand, which requires adding additional capacity. Increasing capacity may involve multiple alternatives for which little practical guidelines currently exist. This research investigates, by using simulation approach, the implication of adopting five possible alternatives of increasing job shop capacity and flexibility in terms of their system performance subjected to varying levels of incoming orders and order priorities. The measures of system performance are i.) minimization of tardy jobs, ii.) level of WIP and iii.) machine utilization. A case study of a mold and die machine shop was used as the basis of the research. It was found that the most optimum alternative in increasing capacity is by selectively introducing machines to duplicate existing ones as opposed to replacing existing ones by a single flexible machine capable of performing operations previously done by several machines. The result of the study also serves as a practical guideline to the managers wishing to add capacity in similar circumstances. This however must be taken within the limitations and constraints of the case study

Guideline for improving capacity of a job shop based on selected performance measures

Manufacturing companies are required to fulfill customer’s driven imperatives such as on time delivery as well its own requirements such as high machine utilisation and low work in process. In order to achieve these, manufacturers need to adopt the right manufacturing strategy. Selecting the right manufacturing strategies will improve its capability to meet its customers demand as well as its ovvn limitations. This research identifies five strategies that a job shop may adopt to achieve flexibility in meeting demand. The five strategies ranges from the basic strategy of having a complete set of single–operation machines to flexible multi–operation machines. Each strategy is evaluated and a set of guideline is proposed. The results show that when job tardiness and work–in–process is the performance criteria, the duplication strategy is the best. However, if the performance criteria is machine utilisation, then the best strategy is the replacement strategy