THE LUMBER PROCUREMENT AND KILN SCHEDULING PROBLEM: A HYBRID-GA APPROACH

摘要

A complex scheduling and inventory allocation problem occurs in case goods furniture manufacturing. The problem is to satisfy the dried lumber demands of a furniture plant's rough mill by either drying green lumber in-house or by outsourcing (purchasing commercially kiln-dried lumber). The process of drying green lumber is a time-consuming batch-oriented process, resulting in large dry lumber inventories. The managerial objective is to minimize the costs of procuring the required quantities of lumber, drying green lumber, and carrying inventory while meeting all demand due dates over a planning horizon. The problem is decomposed into two sub-problems: 1) the scheduling of the lumber types (lumber species/thickness combinations) in the kilns; and 2)satisfying demands through the allocation of dry lumber inventory or through outsourcing. A hybrid-genetic algorithm determines the best sequence of lumber types to dry in-house, and a constructive algorithm allocates the inventory and determines the quantity of outsourced lumber that minimizes total cost. The effectiveness of the hybrid-GA algorithm in solving the problem is demonstrated in an industrial case study.