6-Sigma process capability studies
Six-sigma is a set of tools and techniques, which are used increasingly as a means to achieve improved process control. It was developed by Motorola in 1986 and became a central pillar of General Electric’s business strategy in 1995.
Six-sigma originated from statistical modelling manufacturing processes. A six sigma process is one in which 99.99966% of products is defect free (i.e. 3.4 parts per million defective), The six Sigma goal allows for the difference between short term which would be seen as a result of limited random sampling and long term variation which approximates to a ±1.5σ shift in the distribution.
Six-sigma can help to achieve a predictable, stable process through a process of continual improvement; a process with reduced process variability, always providing the processes concerned have characteristics that can be measured, analysed, controlled and improved.
To be totally effective the 6-sigma process should be embedded within the company strategy, as a top down initiative; and a continual evaluation of approach and priorities is required to ensure that the process works correctly and appropriately for each individual application.