During the last two decades much has been written about Lean and 6 Sigma, the fundamental premise of the two approaches respectively being the elimination of waste and the reduction of variation. Many large companies have both Lean and 6 Sigma programs that have been branded Lean 6 Sigma, Power Lean, Lean Sigma, Quick Sigma to name but a few. In some cases, companies are using Lean to remove waste from non-value adding activities and 6 Sigma to control the variation within the value-adding portion of the process. The integration of Lean and 6 Sigma has become fashionable, but what are the real differences and can they really work together?
The adoption of Lean techniques prior to the application of 6 Sigma can provide real benefits as it allows you to firstly address those issues that can be resolved quickly and easily, the ‘low-hanging fruit’, and most importantly, it allows to streamline and improve the overall process before trying to control the variation within it – 6 Sigma. A typical example is an office or factory environment where the layout of the facility is disjointed and not conducive to creating proper flow which leads to increased process times, quality issues and decreased customer value. By first improving the overall layout, many wastes are immediately eliminated. It does not make sense to control the variation of a process with 6 Sigma if the process is fundamentally flawed…..first fix the process using Lean techniques, then control it!
Although Lean techniques are very useful for basic projects, 6 Sigma adds an in-depth analysis where the problems are more complex, specifically in a high volume production environment. However, in most companies there are a multitude of relatively simple processes that do not require complex statistical analysis, for example customer order processing, order picking & dispatch, production scheduling, invoice generation, goods receiving and creating purchase orders. Using Lean techniques, such processes can usually be analysed and improved (simplified), without the necessity of 6 Sigma. It should be noted that Lean’s focus on simplicity and people involvement across the entire organisation, as opposed to the 6 Sigma emphasis on experts (black and green belts), bodes well for the long-term sustainability of Lean and helps create a culture of continuous improvement within the organisation.
The bottom line?
Lean and 6 Sigma can work well together, but the starting point must be Lean. Identify the value stream, eliminate waste and improve the overall process before trying to control variations within the process.