(72r) New Development on Hoist Scheduling for Multi-Stage Material Handling

New Development on Hoist Scheduling for Multi-stage Material Handling

HonglinQu, Chuanyu Zhao and QiangXu*

Dan F. Smith Department of Chemical Engineering

LamarUniversity, Beaumont, TX77710, USA

Abstract

            Multi-stage material handling (MSMH) processes are widely used in industries for the manufacture of various workpieces and products (jobs) in large scale. Generally, a hoist, as control device, will handle all jobs by following a preset movement schedule, including joblifting, releasing and moving along a production line. Lots of engineers have studied the feasibility and optimization of hoist movement schedules. However, the productivity of an MSMH process not only depends on the hoist schedule, but also relies on the production line arrangement, such as the spatial allocation of processing units. During production, hoist will travel forth and back to pick up job from its current unit and release it into the next one, following its processing requirement. In this way, a proper arrangement of unit position would dramatically shorten the total moving time and improve the processing capability. As far as we know, no work has been done in this field. Therefore, we try to arrange the unit allocation in a more compact way to optimize the hoist schedule.

            In this paper, a two-dimensional (2D) matrix arrangement of processing unit has been proposed to replace original one-dimensional (1D) line arrangement for the optimization of productivity, and a mixed integer linear programming (MILP) model has been developed to solve this problem. The major advantage of this study is that the compacted allocation provides shorter paths for hoist to move, so the productivity could be improved significantly. The efficacy of the proposed methodology is demonstrated by a case study. The comparisons between 1D and 2D production line arrangements have also been conducted.