DEVELOPMENT OF A SKILL-BASED JOBS PROCESSING MODEL ON MULTI-MACHINE UNDER FIXED MAINTENANCE PERIOD

Abstract

Scheduling is a crucial resource in manufacturing jobshop. Manufacturers are been forced to seek effective schedules in coordinating machines and operators so as to bring down cost accompanied with setup, goodwill, inventory and labour due to rising demand for on-time delivery of products. In this study, an experimental model for the scheduling of jobs based on operator’s skills under fixed maintenance period was developed. The model criteria for scheduling of jobs on machines under variable operators skills were identified as job type, operation sequence, machine type, processing time of elemental activities and jobs relation. The criteria were integrated into the model with the objective of minimizing makespan by considering alternate route based on available machines and skill levels. The model was tested by data obtained from experimental study of jobs carried out on machines with operators of different skill levels. The practical result was compared with the ones examined from the model using computer software SPSS version 15. Based on the variation in completion time ranging from 33 minutes to 171.3 minutes for the production of nut, bolt and gear with different operator skill levels (highly-skilled, skilled and semi skilled), the practical results from the jobshop under different skill levels were similar to the result obtained from the theoretical model.This showed that the software model can adequately represent the job routing system in the jobshop under different skill levels