Investigating implementation issues for workload control (WLC): A comparative case study analysis

Abstract

Workload control (WLC) is a method of production planning and control, which when commenced at the customer enquiry stage, has particular relevance to producers of highly customised products. Although previous research has suggested that WLC has great potential to improve performance, only a few successful case studies have been reported. To facilitate more widespread use of WLC, this paper seeks to investigate issues that arise from implementing WLC systems through a rare comparative case study analysis. Two companies are studied, a capital goods manufacturer and a precision engineering sub-contractor. The study initially identifies emerging research questions that address 17 implementation issues, including those related to the market/customer, the primary manufacturing process, the WLC system requirements, the flow of information and embedding WLC within the organisation. For each implementation issue, an appropriate response is given that leads to changes in the theory underpinning WLC or the development of WLC implementation strategy. Finally, areas in need of further research are suggested, providing direction for fellow scholars in the field of WLC. These areas include the further refinement of the implementation requirements for WLC in additional case study settings and the need for simulation studies to verify the effectiveness of some of the proposed changes to the underlying theory of WLC.

Introduction

As customers become more demanding, the need for industry to provide more highly customised products continues to increase. Thus, the make-to-order (MTO) sector of industry is of continued importance, and includes capital goods manufacturers as well as many small- and medium-sized enterprises (SMEs), providing customised goods as part of a supply chain. In a recent review of the production planning and control (PPC) literature by Stevenson et al. (2005), in which workload control (WLC) is described, it has been argued that WLC is the approach with the highest relevance to many MTO companies, given that it provides more of the required features than the other alternatives. For example, WLC explicitly addresses the customer enquiry stage at which many such firms are involved in competitive bidding, enabling both realistic and competitive bids to be determined. In addition, it has also been recently argued that WLC has the potential to enable MTO SMEs to be more effectively integrated into the supply chain (Hendry, 2006). Thus, research into WLC to date has concluded that it has the potential to significantly improve the operating performance of the MTO sector of industry.

The overwhelming majority of contemporary research in the field of WLC is simulation based: see, for example, Perona and Portioli (1998), Oosterman et al. (2000) and Henrich et al. (2006). Although some recent experiments have explored ways of replicating real-life job shops in a simulation environment (for example, Bertrand and Van Ooijen, 2002), it has been acknowledged that the job shops found in practice are much more complex than those used as the basis for most simulation models (see Perona and Miragliotta, 2000). Thus, to gain a more detailed understanding of the effect of WLC on performance in practice, case study evidence is needed. Despite this, empirical studies are comparatively few and far between, the most notable contribution in recent times being by Park et al. (1999). A consequence of the lack of empirical research is that little has been written about the process of implementation itself in a WLC context. This paper seeks to address this gap in the literature, thereby facilitating more widespread implementation of WLC.

It is noted that it is inevitable that some of the issues critical to the implementation of WLC are also important to the application of other company-wide initiatives; however, it is not our aim to rediscover issues such as the need for careful change management, to have top-level management involvement and to ensure the project is championed. Instead, this paper seeks to build on this, adding new and much needed insights into implementation issues that are specific, or of particular importance, to WLC due to its characteristics, data requirements and so on. Such insights may consequently ease the implementation process or lead to changes (or simplifications) in the associated WLC methodology. The relevance of these insights can then be investigated in the context of other innovative PPC systems, such as POLCA (see Suri, 1999) and CONWIP (see Hopp and Spearman, 1996).

The remainder of the paper is organised as follows. A more thorough review of the relevant literature is given in Section 2, where this need to investigate implementation issues is further justified. Section 3 describes the research methodology undertaken, indicating that a comparative case study analysis has been used to first identify and explore the implementation issues that arose and then to consider how these issues can be addressed. It is noted that there are a number of different approaches to WLC, the particular approaches used in this study are therefore briefly described in Section 4. The main focus of the paper, the discussion of the implementation issues, is then presented in 5 The investigation of implementation issues: case study evidence and emerging research questions, 6 Discussion of the case study evidence: addressing the research questions, with the former presenting the case study evidence and the latter providing detailed discussion. Finally, in Section 7, conclusions are drawn along with the identification of areas in need of further research.