Optimisation oriented lean six sigma development for maintenance management in service sector

Abstract

This research deals with the optimization of preventive maintenance (PM) and process improvement for maintenance management in service sector. To stay competitive and sustain long-term profitability, process improvement methodologies have become strategically important for maintenance management in recent years. These include well-known approaches such as Total Quality Management (TQM), Business Process Reengineering (BPR), Six Sigma, Lean and Lean Six Sigma (LSS). The adoption of LSS and PM optimisation in the maintenance services sector, however, is still at an early stage. There has been very limited research in this topic reported in the literature. This research has explored the LSS and PM optimisation through case studies in vehicle fleet maintenance. This research has made contributions to knowledge in the quality management and, in particular, the process improvement methodology and service quality for the vehicle maintenance service sector, but potentially also in a broader context. The main contribution is the establishment and demonstration of a sound methodology and model to integrate LSS and PM optimisation in the vehicle fleet maintenance. The model also provides guidelines for further development of a practical process improvement framework. The proposed model is therefore considered as a basis for further empirical work relating to the process improvement in the services context. Further, this study has developed a total cost model to optimise the PM activities based on both the PM maintenance cost and the quality loss cost. There have been two parallel developments for determining the optimum PM interval, one based on the maintenance cost without considering the quality loss, and the other based on the quality loss without considering the maintenance cost. A novel approach combining the maintenance cost and quality loss has been developed. Moreover, the total productive maintenance (TPM) implementation in the service process and the integration with the LSS/PM optimisation has enhanced the theory and practice of continual improvement in maintenance. The implementation of the integrated model of LSS and PM optimisation through case studies in vehicle fleet maintenance has provided an impetus for establishing best practices within the organisation under study. The implementation of this model has also increased the future performance of the organisation. It has enabled the maintenance management based on a strong customer-supplier relationship by satisfying customer requirements. The proper utilisation of the resources and the application of LSS tools and techniques will upgrade the company procedures and reduce the maintenance non-conformities, with the key process parameters continually improved and ultimately optimized.