How important is the batch splitting activity in scheduling of virtual manufacturing cells (VMCs)?

Abstract

Especially developed for small-to-medium companies that perform batch production, virtual manufacturing cells (VMCs) have attracted some researchers’ close attention as they provide greater flexibility associated with flexible manufacturing systems (FMSs) and some of the scheduling simplicity related to cellular manufacturing systems (CMSs) without incurring much additional system cost. In a VMC, machines are dedicated to a part as in a regular cell, but machines are not physically located in a contiguous area. Batch splitting (also called lot streaming) activity emerges as a key element that management must decide whether to apply it. In this paper, we consider the case where there are multiple jobs with different processing sequences. There are multiple machine types, each of which has several identical machines and identical machines are distributed through the shop floor. Two scheduling objectives are makespan minimisation and total travelling distance minimisation. Under these circumstances, we developed two mixed integer linear programming (MILP) formulations with and without batch splitting. On a broad range of test problems, performances of the models are compared with each other and computational results show that batch splitting leads to more desirable system results while it increases the computational time. The decision maker or manager should make a trade-off between system performance and computational time efficiency.

Keywords:

• virtual manufacturing cells (VMCs)
• lot streaming
• flexible job-shop scheduling problem (fJSP)
• scheduling
• mixed integer linear programming (MILP)
• flexible manufacturing systems (FMSs)