A Tactical Planning Model for Mixed-Model Electronics Assembly Operations

Utilizing the automatic assembly machines effectively is critical for electronics assembly operations. This paper develops an optimization model and methodology to assign product families to parallel placement machines in a high mix, low volume environment. Unlike strategic and operational models that emphasize either workload balancing or setup optimization, our tactical planning model incorporates both factors by minimizing the total setup cost per demand period while ensuring that none of the placement machines is overloaded. To capture the impact of product assignment decisions on setup cost, we consider a partial setup policy of mounting some components permanently on each machine and loading other components as neeclecl for each product. We formulate the tactical planning problem as an integer program, and show that even the special case of minimizing setup cost on a single machine for a given assignment of products is NP-hard. Our solution method combines column generation, heuristics, and lower bounding procedures. We solve two practical subproblems - a product selection subproblem, and a setup optimization subproblem - that apply directly to short-term production planning. Our computational experience shows that the algorithm performs well, and provides insights regarding the effective implementation of column generation for this problem context.