Optimising recipes in hybrid continuous-batch manufacturing systems:application in the multi-layer plywood industry.

Many companies in the upstream segments of value chains combine continuous or semi-continuous processes with batch manufacturing. These companies face problems such as an increasingly high variety of final products being demanded by markets, a high incidence of raw materials in the cost structure and intensifying international competition. This paper deals with the rationalisation of recipes and bills of materials, which is one of the key problems encountered by such companies. The work uses an optimisation approach and proposes mixedinteger linear programming models for the case of multi-layer plywood and blockboard manufacturing, developed in cooperation with one of the major Italian manufacturers. The preliminary results achieved to date are broadly aligned with the cost structure and recipes currently being used by the firm, but introduce substantial elements of improvement, especially in the reduction of the number of recipes.