Machine and labour planning in layout design

In this paper the authors describe a model included in a plant layout design support system. The model is aimed at supporting the joint definition of equipment and labour requirements in production systems. The problem of specifying such requirements so as to minimise total production and subcontracting costs is modelled as a mixed integer linear program. This model includes constraints on investment and hiring of skilled labour, takes into account current availability of equipment and manpower, and handles situations involving production shifts, overtime and subcontracting of parts. Computational results derived from several branch-and-bound strategies adopted in solving the mixed integer linear program are compared for a large set of problems generated so as to represent a wide range of real life situations.