Mathematical models for FMS loading and part type selection with flexible process plans

The loading problem in flexible manufacturing systems (FMS) consider several different manufacturing settings and objective functions but some crucial aspects of FMS environments, such as flexible process plans (FPP), have not yet received adequate attention. FPPs are vital in coping with bottlenecks and breakdowns, and decreasing the flow time. Modelling FPPs within a loading model, however, increases the problem complexity. In this study, we work on the integrated version of FMS part type selection and loading problems, and propose two models that consider operation allocation at different levels of detail for an FMS with FPP. Operation allocation is modelled explicitly along with tool loading in our first model, while the second one considers it implicitly to obtain a more compact and efficient formulation. Both models show remarkable reduction in run time compared to an existing loading model proposed for a similar FMS environment. [Received 19 August 2012; Revised 15 November 2013; Accepted 21 November 2013]