One of the more common buzz words in manufacturing is six sigma and lean manufacturing. This leads to the question what exactly is six sigma? This can be define differently based on your context. In statistics 6 sigma means 6 standard deviations from the mean, or 0.00034%. That’s a really small number right? The six sigma methodology is a collection of tools that will aid your manufacturing to obtain a 3.4 defects per million units. That seems a little obnoxious right ? To only have 3.4 defects per million!!! What if that metric was not for a
defective widget, but rather a defective aerospace component. That failure would be catastrophic to the passengers, family members, and the company making the part.
The metric is a measurement of quality in your manufacturing process. The higher the sigma level (standard deviation) the less defects you produce. This level of accuracy is considered the crown jelel in manufacturing quality in most industries. With that said some industries will require a greater sigma level.
Six-sigma is most well known as a process for continuous improvement. It is a five stage data driven method to methodically look at your process and identifie the crucial deffencies. The five stages are known as the DMAIC Methodology. The DMAIC methodology is a very structured way of defining a business problem, finding out what needs to be fixed or changed, getting the answers on how to change it, implementing the changes, and then making sure the changes beneficial and sustainable
Define-The Define phase is where the problem statement and scope of project are defined and put down in writing.
Measure-This phase is where metrics and measurement systems for the inputs and outputs of your projects are formed. This phase is also to ensure that you are getting the right data from the right place and also that the way you are getting your data is accurate.
Analyze-In this phase, you collect data on all your inputs and outputs and then use one or more of the statistical tools to analyze them. This eventually leads you to isolate the root causes of your problem and provides insight into how to eliminate them.
Improve- In order to create the implementation plan, you need to gather up all the conclusions that have been formed through the analysis that you have done. Now that you know what improvements need to be made, you have to figure out what you need to do in order to implement them.
Control-This phase is where you make sure that the improvements that you have made stay in place and are tightly controlled. By the time you reach the control stage, you would have reached the end of your input filtering or funneling process. You should now be left with the main 3 or 4 extremely critical inputs that have a significant impact on the output.
History of six sigma
Six Sigma was a standard of measurement in process and product variance when Walter Shewhart demonstrated three sigma from the mean is when the process needs to be improved. Many standards later came in the industry but Bill Smith, a motorola engineer, was given credit for naming six sigma.
With Chairman Bob Galvin at the reigns, Motorola designers determined that the standard quality measurement in defects per thousands didn’t provide enough resolution to improve on. Instead, they set out to measure the defects per million. This new standard required an entirely new culture and set of methods to achieve. A$16billion dollar savings has been achieved by Motorola due to the implementation of the six sigma mindset.