EMBEDDING JIT IN MRP - THE CASE OF JOB SHOPS

The philosophy and principles needed to institute JIT in any system, i ncluding a job shop, are described. A simulation model is developed us ing a benchmark job shop to study using a pull system in a job shop ha ving variations in processing times, load levels, and machine breakdow ns. It is inferred from simulation that JIT can be implemented if cert ain conditions are met. Processing time variations did not pose a seri ous impediment, but load levels and machine breakdowns were critical f actors. With uneven loading, the resulting capacity bottlenecks make t he pull system look like a push system. This can be avoided by process ing a uniform mix of jobs to not violate workstation capacity limitati ons. If machine breakdowns are unavoidable, maintenance of buffer capa city is essential.