Application of lean six-sigma methodology to reducing production costs: Case study of a Portuguese bolts manufacturer

This study describes a procedure that applies the Lean Six-Sigma approach to reducing the production costs of a Portuguese bolts manufacturer. The project was proposed by the product’s customer, who suggested improving some parameters of the processes associated with its manufacture. The customer’s expectations and requirements are called ‘Voice Of the Customer’ (VOC) focusing on the reduction of production costs. Bolts manufacturing has some particularities, such as the considerable lot-size and the high level of products produced. Some of the important Six-Sigma and Lean tools are discussed, which will be of help to Six-Sigma practitioners. The empirical study illustrates methods used to Define, Measure, Analyse, Improve and Control (DMAIC) the Six-Sigma approach. This study consolidates the efficiency and the excellence of the DMAIC methodology, providing arguments to demonstrate its usefulness for the implementation of improvements, both in terms of quality and in terms of the effectiveness and efficiency of the processes. This case reveals that there exists an important complementarity between the methodology used and the Lean Six-Sigma concepts when dealing with a continuous improvement project in the context of bolts manufacturing. The findings reinforce conclusions from other studies that the DMAIC methodology can be used in any improvement project, and not just for Six-Sigma projects, whence the methodology emerged.