Lean and Six Sigma theories and applications are both nowadays widely spread around the world. Finding their root origins in Toyota and Motorola, and then largely adopted by many companies, their individual success is unquestionable. However, a new trend appeared so as to combine the two approaches into a single one, called Lean – Six Sigma (LSS), or sometimes known as Lean Sigma.
This paper will investigate the potential advantages and disadvantages of such a combination. The means to present a fair investigation will be supported by both a literature review on the subject and practical examples of Lean – Six Sigma companies. The extent of the research takes the business world as a whole, from manufacturing to service and public sector.
The work follows the inquiry of two research questions, based on personal knowledge. They will then be assessed and confronted to the literature and real case studies. Through this, findings are finally presented as to answer the initial question.
英语论文怎么写 Lean Six Sigma Advantages and disadvantages of alignment
According to what Pepper and Spedding (2010) report from the literature review of the Lean – Six Sigma implementation, little has yet be done in practice to combine these two theories. Sources of explanation are a lack of commitment from management. Moreover, such an implementation is thought to potentially create subcultures and lead to conflict of interest. On his side, Bendell (2006) acknowledges that literature about Lean – Six Sigma is limited and even disappointing.
The popularity of Lean – Six Sigma is also limited in the service industry. This is mostly due to the nature of processes in service, as most of them are unseen, intangible and potentially unmeasurable (Charkrabarty and Chuan, 2007).
As stated, the first hypothesis assesses the potential advantages or disadvantages from Lean – Six Sigma introduction in a company. This paper considers this approach as not a brand new one, meaning that it doesn’t propose a drastic new theory, but rather combine Lean thinking and Six Sigma.
Therefore, one could suppose that both theories’ characteristics are present in LSS. The very first logical question for executives and managers is how to implement this combination, and by extension, does it present drawbacks?
Starting from literature review about Six Sigma and Lean thinking taken separately, a fair estimation would be that Six Sigma would be used as the core framework while Lean approach would be implemented as a tactical tool, or weapon, aimed to eliminate waste and non-adding value activities in the process. This hypothesis is supported by the integrated DMAIC process in Six Sigma approach, as well as its implementation strategy definition (Eckes, 2003).
Nevertheless, the literature review appears not to consider this approach as a valid one, as nor theoretical nor practical proof or reports exist. On the contrary, two other theories distinct themselves: a co-ordination between both approaches at the same time, and lean thinking complemented by Six Sigma. A final notable point is the poor availability of unambiguous and structured implementation plans, which could have provided a “how-to” guide for LSS achievement.
The co-ordination between both approaches
Most of the work under this approach is based on the fact that one theory actually fills the gap of the other’s flaws. In other words, rather than seeing a simple addition of tools, techniques and strategies, LSS provides synergy between Lean thinking and Six Sigma, enhancing both of them.
Arnheiter and Maleyeff (2005) list similarities between Lean and Six Sigma as both involving cultural changes, new approaches to production and servicing customers, as well as a high degree of training and education (from shop floor workers to management).
But on the other hand, Lean carries a burden of being seen as an approach that leads to layoffs, as employees see “waste elimination” going with sacking workers that perform non value-adding activities.
Meanwhile, Six Sigma is sometimes considered as a consultancy package, “old vine in a new bottle” in other words, that actually regroups various incumbent tools and techniques (T&Ts) under a new etiquette. Another aspect of the resistance is the “fear of statistics” which is in the heart of the Six Sigma approach that prevents executives and/or employees to fully embrace the theory.
As a consequence, one could argue that both approaches complement each other to remove resistance to change, so as to Six Sigma brings an overall staff awareness of the approach – as well as a structured framework (DMAIC) – while Lean philosophy is a well-established practice, which founder (Toyota) still outclasses most of its competitors in the car manufacturing industry. In other words, one philosophy supports the other against reluctance to change.
Moreover, Lean is backed up by Six Sigma ability to use data and facts in the decision-making process, as well as methodologies that promote a more scientific approach to quality (Arnheiter and Maleyeff, 2005).
An example is the Ford transmission issue (Gunter, 1987 cited in Arnheiter and Maleyeff, 2005). Transmissions were both manufactured in the US and in Japan but the customer quality rating privileged the Japanese products. Investigations showed that the American transmission presented a higher level of technical variation. Only using Lean approach (i.e. “go-no go” inspections) clearly fails to prevent such malfunction in the quality process. That is why including Six Sigma measurement, which narrows down the risk of variation, will both increase quality and customer satisfaction.
Six Sigma can also rely on Lean thinking as, for example, a company using a batch-and-queue model can still perform extremely well according to Six Sigma principles, but such production organization is likely to increase lead time and be limited in responsiveness and flexibility (Womack, 2003).
In more practical terms on how this integration works, Figure 1 (Carleysmith et al. 2009), explains quite well the “repartition of tasks” between Lean and Six Sigma.
A more critical analysis could argue that even if this representation proposes a straightforward understanding, when applied in practice, one could fear that complexity of the organization and/or its processes, as well as the link between outputs and inputs, will cause this model to be extremely difficult to implement. In addition, possible conflicts between both approaches are not mentioned. Finally, this model doesn’t suggest any real integration concerning resources allocation, training and education of staff, roles and responsibilities specific for a LSS approach.
Interestingly, another framework for LSS proposes to combine both five main steps from each theory (Byrne et al. 2007) into a single one. This has the advantage of providing a more integrated approach but it lacks a tactical proposition.
英语论文怎么写 Lean Six Sigma Advantages and disadvantages of alignment