2 Lean manufacturing system: an overview
The Toyota production system (TPS) [15] was introduced to the west as lean manufacturing by Womack and Jones [23]. Lean thinking is a management philosophy that focuses on reduction of what is seen as waste in an organization. A LMS helps to reduce waste in the manufacturing process and permits the company to focus on customer value [22]. Dombrowaski et al. [6] maintain that LMS provides a holistic strategy to eliminate waste in processes, achieve high product and process quality, and reduce lead time. They also emphasize that LMS is a company-specific compilation of rules, standards, methods, and tools, and provides an appropriate underlying philosophy and culture for the comprehensive and sustainable design for manufacturing products.
TPS is often described by mean of a house (Fig. 1) [8]. One pillar of the house represents just in time (JIT). JIT as one of the key principles of lean manufacturing suggest that, instead of conventional approach of pushing value forward, customer should be allowed to “pull” the value as and when needed. This approach helps in avoiding waste of over production. The other pillar, Jidoka, is about ensuring that quality product is made and any opportunity to produce defects is eliminated. Poka yoke or fool proofing is one of the most popular term used in lean manufacturing, which means to design a system which has a capability of preventing a defect and if a defect occurs, detecting the defect itself. Six-sigma has also gained ground as an approach to optimize process performance. At