Job shop scheduling considering material handling process

Abstract

This paper discussed job shop scheduling considering material handling process. This process is a very important aspect on a flexible manufacturing system, where raw material or semi-finished goods are delivered from one processing point unto another by utilizing automated material handling equipment, functioned as shared resources. The starting time of each process is affected by the ability of the material handling equipment to conduct timely delivery from one point to another, therefore considering this process unto scheduling is important to enable planner to get precise estimation of the process makespan. We take the case where the flexible manufacturing system is consisted of four identical machines; each has the capability of processing various jobs due to the various cutting tools installed on their tools magazine. Jobs are dispatched based on longest processing time rule and then allocated to machine which has minimum load. Being a shared resource, material handling equipment has pick-up and delivery priority rule when handling multiple requests. The two most common rules are longest waiting and closest entity. This paper will analyzed the impact of each rule to the process makespan and material handling equipment utilization. Simulation model were built using Promodel to give decision maker better visualization of the system under consideration.