Assignment problems in single-row and double-row machine layouts during slow and peak periods

Given the plant layout, the number of workers, the maximum number of machines that a worker can handle, and the preferences between each worker and each machine, the problem to minimize the deviations of workloads assigned to workers and to maximize the total preference between each worker and each machine is considered in the semiconductor industry. The number of workers is fixed (no part time workers) because of the high expense of technology education and the increase of current employees. Since the workforce assignment problem in this article is in NP class, several heuristic algorithms are presented according to two types of plant layouts during two types (slow and peak) of periods. The proposed algorithms are developed based on the combination of a mixed model scheduling, simulated annealing technique and graph theory. The solution generated satisfies the zone constraint (machines assigned to a worker are adjacently located). Computational results show that the presented algorithms can find a good solution quickly.