Evaluation and Improvement of Makespan Time of Flexible Job Shop Problem Using Various Dispatching Rules—A Case Study

Makespan time is an important parameter in any industry which affects the production schedule adherence to meet delivery dates. In this work, the various dispatching rules are applied to study its effect on the makespan time of the small-scale industry located in central India. The various dispatching rules such as first come first served (FCFS), shortest processing time (SPT) and longest processing time (LPT) is applied to study its effect on the makespan time with the data and information obtained from small-scale unit involved in metal press working operations. The open sources LEKIN software is used to simulate these dispatching rules. The analysis has been carried out for existing resources and it is observed that LPT can fulfil 78% of scheduled deliveries, SPT can fulfil 63% scheduled deliveries and FCFS can fulfil 66.13% scheduled deliveries. The resources, i.e. machines addition is proposed to meet the schedules based on the bottleneck observed in Gantt chart obtained from the software for various dispatching rules. By applying the heuristic approach, it is observed that the addition of a combination of one shearing machine, one 100 Tonnes power press (TPP), and one 20 TPP can lead to the reduction of makespan time by 26% with LPT strategies.