Lean Six Sigma is the connexion (to borrow the name of NGN monthly bulletin) between, the Lean and Six Sigma, two major continuous improvement philosophies which developed during the late of 20th century.
First, Lean has a long history, its roots based on the lean production in 1950's from the Toyota Motor Corporation, under the leadership of Taiichi Ohno, when they developed the well-known Toyota Production System (TPS). However, the first entrance of the term ‘lean production’ in the public came later on in 1990 when Womack et.al (1990) published the book The Machine that Changed the World. The progress of Lean is continuing until now; terms such as Lean manufacturing, Lean thinking, Lean Assessment, Lean Enterprise, Lean Culture and recently, the Lean Start Up have appeared in the academic and business world. Moreover, a lot of examples of organizations with successful transformation of Lean thinking have appeared. The five principles of Lean are presented in figure 1, which is the cornerstone of Lean. In addition, there are several tools of Lean implemented in each of these principles, as the Value Stream Mapping, 5S, Kanban, Kaizen etc. The basic idea of Lean is the improvement of efficiency by removing wastes and creating more value.
Figure 1. Principles of Lean. (Picture retrieved from Lean.org)
Secondly, the origins of Six Sigma derive, since the late 1980's, from Mario Perez-Wilson under the leadership of Bob Garvin in the Motorola Company where they developed the Six Sigma as a cornerstone activity to achieve high quality standards and increase revenues at the same time. Motorola won the Malcolm Baldrige National Quality Award in 1988 and became popular about their achievements with the use of Six Sigma (Pyzdek& Keller, 2010). A lot of companies as Allied Signal, GE and Honeywell designed their quality programs based on the Six Sigma in the 1990's managing and displaying an achievement of improved product quality, optimum customer satisfaction and production cost reduction. This achievement was based on the aim of a target of no more than 3.4 defects per million opportunities (DPMO) in operational processes based, fundamentally, on the statistical perspective of Six Sigma. The Six Sigma is based on the DMAIC approach (Define-Measure-Analyse-Improve-Control) with statistical and quality tools developed in each phase, from the project perspective. Figure 2, presents some tools-techniques of Six Sigma in each project phase of the DMAIC approach. The basic idea of Six Sigma is the improvement of process capability by reducing variation.
Figure 2. Six Sigma tools in each phase of a project. (Retrieved: Pyzdek & Keller, 2010)
Finally, in the early 2000's, many manufacturing companies have implemented Six Sigma programmes and achieved World Class quality standards. Nevertheless, they didn’t achieve on-time deliveries and they were not able to reduce lead time (George, 2002). One of the first companies which implemented Lean Six Sigma was Caterpillar registering an achievement of profit increase of around 80% in four years. Furthermore, a new trend has started to be developed and implemented, that is, the expansion of the Lean Six Sigma approach in the manufacturing and services sectors over the last decade.
However, as mentioned before, these two approaches are based on different philosophies, the Lean focussing on the reduction of waste and the Six Sigma focussing on the reduction of variation; the Lean emanating from Eastern Culture and developing over a long period of time, enriched by elements based on continuous learning and coaching while the Six Sigma emanates from Western Culture, based on the realization of profit and the hierarchical management system based on the belt certification. On the other hand, the implementation of Lean Six Sigma creates this competitive advantage for improvement in efficiency and capability primarily by eliminating wastes and variation at the same time.
In conclusion, there are a lot of different perspectives about the combination of Lean and Six Sigma from practitioners and academics as well; however, the use of lessons learned as a navigator to avoid recurring mistakes, and the emergence of success factors related to Lean and Sigma will drive the next generation of Quality Leaders to a more sustainable and successful implementation of Lean Six Sigma.
George, M.L. (2002). Lean Six Sigma: Combining Six Sigma quality with Lean speed. New York: McGraw-Hill.
Pyzdek T., Keller P.A. (2010), The Six Sigma Handbook: A complete guide for Green Belts, Black Belts, and Managers at All Levels. 3rd Edition. McGraw-Hill. USA.
Womack, J.P., Jones, T. and Roos, D.T. (1990), The Machine that Changed the World, Rawson Associates, New York, NY.