1. Introduction This study examines the performance of order release control one of the main functions of – production planning and control (e.g. Bertrand & Wijngaard, 1986; Zäpfel & Missbauer, 1993) – in job shop-like production environments typical of many small and medium sized make-to-order companies. When order release control is applied, jobs do not enter the shop floor directly. Instead, they are retained in a pre-shop pool and released using criteria that allow the shop to achieve certain performance targets, e.g. to restrict the level of work-in-process inventory and/or maximize due date adherence. Well-known approaches to order release control include: Kanban (e.g. Shingo, 1989); Drum-Buffer-Rope (e.g. Goldratt & Cox, 1984); Constant Work-in-Process (ConWIP, e.g. Spearman 1990); and, Workload Control (e.g. Land & Gaalman, 1996). et al., Such control systems are widely applied in practice. For example, Wisner (1996) reported that about 40% of US machine shops in their sample used some form of order release control, and White (1999) reported that about 50% of small and 70% of large companies use Kanban et al. control. This study concentrates on the Workload Control concept that was developed for such high-variety contexts as the make-to-order job shop (e.g. Zäpfel & Missbauer, 1993; Stevenson 2005; Thürer 2014). et al., et al., An effective order release control mechanism for job shops combines two functions that determine performance (e.g. Land, 2006): (i) a load balancing function, so workloads are not only kept within limits or norms but are distributed fairly evenly across resources (Thürer et al., 2012); and (ii) a timing function, so jobs are released such that their due dates can be met. We examine how these two functions are affected by the sequence in which jobs are considered for release an important aspect of order release neglected by prior research. This will have direct –
1. Introduction This study examines the performance of order release control – one of the main functions of production planning and control (e.g. Bertrand & Wijngaard, 1986; Zäpfel & Missbauer, 1993) – in job shop-like production environments typical of many small and medium sized make-to-order companies. When order release control is applied, jobs do not enter the shop floor directly. Instead, they are retained in a pre-shop pool and released using criteria that allow the shop to achieve certain performance targets, e.g. to restrict the level of work-in-process inventory and/or maximize due date adherence. Well-known approaches to order release control include: Kanban (e.g. Shingo, 1989); Drum-Buffer-Rope (e.g. Goldratt & Cox, 1984); Constant Work-in-Process (ConWIP, e.g. Spearman et al., 1990); and, Workload Control (e.g. Land & Gaalman, 1996). Such control systems are widely applied in practice. For example, Wisner (1996) reported that about 40% of US machine shops in their sample used some form of order release control, and White et al. (1999) reported that about 50% of small and 70% of large companies use Kanban control. This study concentrates on the Workload Control concept that was developed for such high-variety contexts as the make-to-order job shop (e.g. Zäpfel & Missbauer, 1993; Stevenson et al., 2005; Thürer et al., 2014). An effective order release control mechanism for job shops combines two functions that determine performance (e.g. Land, 2006): (i) a load balancing function, so workloads are not only kept within limits or norms but are distributed fairly evenly across resources (Thürer et al., 2012); and (ii) a timing function, so jobs are released such that their due dates can be met. We examine how these two functions are affected by the sequence in which jobs are considered for release – an important aspect of order release neglected by prior research. This will have direct