The effect of workload control on performance in make-to-order companies

Workload control (WLC) concepts are a new group of production planning and control methods designed to control queues in a job shop manufacturing environment. Their importance lies in the need to maintain this type of flexible manufacturing environment in make-to-order (MTO) companies, which manufacture different products for different customers. There have been several well-developed WLC concepts presented in the literature that address two major decision levels in MTO firms, the job entry level and the job release level. At the job entry level, customer enquiries are processed, and delivery dates (DDs) and prices are quoted to customers. At the job release level, decisions are made regarding which jobs should be released to the shop floor so that processing can commence. The effectiveness of WLC concepts at these two decision levels has been explored in the literature but is still inconclusive, especially in terms of the ability of the job entry level to address one of the most important objectives of WLC – the control of manufacturing lead times. This paper presents a simulation model designed to test the effectiveness of one of the most comprehensive WLC concepts presented in the literature. The model enables the effect of various control parameters within this WLC concept to be explored, including those used at the job entry level to control manufacturing lead times. Experimental results are presented, indicating that this particular concept can lead to lower manufacturing lead times when compared with an environment of no control, even when the same total workload is processed by the shop.