Manufacturing cells design with alternative process plans and/or replicate machines

A first step in the design of a cellular manufacturing system is the decomposition of a collection of machines of a manufacturing facility into smaller subsets, cells, with the aim of enhancing the economics of production. This will determine the overall structure and performance of the production system in terms of material/ parts flow among cells. Several design and operational features and constraints such as an upper limit on the cell size, multiple units of the same machine, allocation of certain machines in the same or different cells and non-consecutive multiple visits of a part to the same machine during its processing, can be taken into account. The objective of the present work is to address the problem of grouping machines into cells and selecting a unique part process plan for each part to be produced, in manufacturing systems where replicate machines and several design requirements as well as operation sequence constraints exist. The problem of assigning parts into part families, which is trivial under the single machine types hypothesis, becomes quite complicated (but more realistic) when more than one unit of each machine type exists. The problem is defined and formulated in a mathematical programming form. A specially adapted two dimensional simulated annealing heuristic has been developed and utilized to get enhanced system configurations of random instances of medium sized production systems.