Freezing the Master Production Schedule Under Rolling Planning Horizons

Abstract

The stability of the Master Production Schedule (MPS) is a critical issue in managing production operations with a Material Requirements Planning System. One method of achieving stability is to freeze some portion or all of the MPS. While freezing the MPS can limit the number of schedule changes, it can also produce an increase in production and inventory costs. This paper examines three decision variables in freezing the MPS: the freezing method, the freeze interval length, and the planning horizon length. Simulation experiment results are reported which suggest that freezing up to 50% of the planning horizon has a marginal effect on production and inventory cost under a wide range of operating conditions. These results also suggest that an order based freezing method produces superior results in comparison with a period based method.production/scheduling: material requirements planning, simulation: applications, inventory/production: planning horizons

Freezing the master production schedule under single resource constraint and demand uncertainty

“…Blackburn et al (1986Blackburn et al ( , 1987 investigated five different strategies for reducing MRP nervousness and found freezing the MPS to be among the most effective strategies. Sridharan et al (1987Sridharan et al ( , 1988 developed a method to measure schedule instability and studied the impact of MPS freezing upon inventory costs and schedule instability in single-level MPS systems under deterministic demand. Sridharan and Berry (1990b) presented a framework for designing MPS freezing methods under deterministic demand.…”

“…Sridharan and Berry (1990a), LaForge (1990, 1994), Lin and Krajewski (1992) extended the studies by Sridharan et al (1987Sridharan et al ( , 1988 from the case of deterministic demand to the case of demand uncertainty by introducing forecasting errors into the system. Lee (1993, 1996) and Zhao and Lam (1997) extended the studies by Sridharan et al (1987Sridharan et al ( , 1988) from single-level systems to multilevel MRP systems and found that some findings in single-level systems cannot be generalised to multi-level systems. Zhao and Lee (1993) investigated the impact of forecasting errors on the performance of the MPS freezing parameters by simulating the forecasting process as well as the master production scheduling and MRP processes in multi-level MRP systems.…”

“…1, Sridharan et al (1987Sridharan et al ( , 1988 suggested two methods of freezing MPS: a period-based method and an order-based method. Using the periodbased method, orders within a certain number of periods in the PH are implemented according to the original plan.…”

“…In a single-level uncapacitated system, Sridharan et al (1987Sridharan et al ( , 1988 fixed the holding cost at $1 per unit per period, and changed the production set-up costs to have different natural ordering cycles. A similar method is also used in this study.…”

“…One frequently used method involves the freezing of the MPS. Several studies have proposed alternative ways of freezing the MPS (Sridharan et al, 1987(Sridharan et al, , 1988 and have compared the effectiveness of freezing the MPS against other methods (Sridharan and LaForge, 1990;Kadipasaoglu and Sridharan, 1995). Lee (1993, 1996) examined the impact of different parameters for freezing the MPS upon total cost, schedule instability and service level in multi-stage systems.…”