Factors affecting schedule instability in manufacturing companies

Abstract

Schedule instability is a major issue in many manufacturing companies. It results in a low service level to customers, high inventory levels, and high costs associated with production changeovers. Much has been written on schedule instability in the literature, but most studies have used simulation and mathematical modelling to look at the internal operations of manufacturing companies. While schedule instability has always been very much a practical problem, there have been few empirical studies presented in the literature. The aim of this research was to obtain the opinions of practitioners on schedule instability, and to identify factors that affect the perceived level of instability experienced by manufacturing companies. An e-mail/web-based survey was administered to practitioners working in the planning and scheduling area. The results suggest that the majority of the respondents perceive schedule instability to be either an important or a very important issue in their operations. Analysis of the responses also shows that schedule instability is affected mainly by external factors, notably relationships with buyers and relationships with suppliers; internal operations have a lower impact. The research moves the debate about schedule instability beyond the current concentration on simulation and mathematical modelling, and from a focus on internal operations to a supply-chain context.

Keywords:

• schedule instability
• buyer–supplier relationships
• supply chain