What is Six Sigma?

What is Six Sigma?
The concepts surrounding the drive Six Sigma quality are essentially those statistics and probabilities. In simple language, these concepts are reduced to, â € œHow sure I can be what I expected to happen actually will happen? â € Basically, the concept of Six Sigma deals with measuring and improving the closeness that come to provide what we planned to do.

Everything we do is variable, if only slightly, the plan. Since no results may not exactly correspond to our intention, we usually think in terms of scale of acceptability for all we plan to do. These ranges of acceptance (or tolerance) to accomplish the intended use of the revenue of our Labors € " needs and customer expectations.

Liena € ™ is one example. Examine how the limits of tolerance can be structured to meet the expectations Customer Care in these two directions:

â € œCut two potatoes in a medium-quarter inch cubes.â € and â € œDrill and Tap two holes of quarter inch carbon steel brackets.â €

What is your range of acceptability € "or € tolerancesâ" for the current value of a quarter inch? (Hint: € 5/16â a cube of potato is probably acceptable, a threaded hole that 5/16â € Probably not.) Another consideration in making potato cubes and the holes are the inherent capability of how to put the quarter inch dimensione € "process capability. Is you hand-cut potatoes with a knife or uses a special machine to cut leaves of memory?
Are you drill holes with a drill or laptop use a drill? If we measure sufficiently filled with potato cubes and holes, the capacities of the various processes that speak to us. Their language is distribution curves.

The distribution curves tell us not only our process of how he did it, but also tell us that the probability that our process will do below. Statistical probability of the Group in these segments of the distribution curve called standard deviation of the mean. The symbol used standard deviation sigma is the Greek lowercase.

For all what is the process with a standard distribution (something that resembles a curve Bell), the probability is 68.26% that the next value will be within one standard deviation from the mean. The probability is 95.44% the following value thereof within two standard deviations. The probability is 99.73% to be within three Sigma 99.994% will be in four Sigma.

If the range of acceptability or limit of tolerance thereof located inside or outside the four sigma point on the curve of distribution for your process, you are virtually guaranteed to produce material acceptable each Timea € "provided, of course, that its process is focused and stays focused on his goal.

Unfortunately, even if you can focus once the process will tend to drift. Experimental data show that most of the processes that control always drifting about 1.5 Sigma on each side of its point central time.

This means that the actual probability of a process with tolerance limits of four sigma, produce acceptable material is actually more like 98.76%, not 99.994%.

To get to the exit near perfect process, the curve for the process must fit within the tolerance limits of such so that the tolerances are equal to or more than six standard deviations, or Six Sigma, in the distribution curve. That's why we call our quality objective Six Sigma.

Quality makes us strong
In the past, conventional wisdom said the costs of higher quality in the long run than poorer quality, increase the price we had to ask for your product and how they are less competitive. Balancing quality with cost was thought to be the key to economic survival. The surprising discovery of business, initially developed Six Sigma, or world-class quality is the best quality does not cost more. Actually costs less. The reason is something that is called the cost of quality. Cost of quality is really the cost of diversion of Qualitative € "pay for things such as rework, scrap and warranty claims. Doing things right the first Timea € "even if it takes more effort to reach this level of performance €" in actually much cheaper than creating and then find and fix defects.

Shooting of Six Sigma
A cautionary tale
The rationale of quality Six Sigma requires some understanding of the role of statistical variation. Liena € ™ SA story about that. Robin Hood is in practice for upcoming archery championship to be held next week the castle. After Robina € ™ s first 100 shots, Friar Tuck, Robina € ™ s Master Black Belt in archery, adds the number of visitors in the bulla ™ € s eye on each target. Robin is considered hit in the eye ™ € bulla 68% of the time.

Brother Tuck plots the results of Robina € ™ s shooting on a graph called a histogram. The result looks something like this. â € œNote bars in the graphic form of a curve that looks something like a bell, â € said the monk. â € œThe is a distribution curve standard. Each process that varies uniformly around a central point to form a pattern that resembles a smooth bell curve, if you make a sufficient number trial or in this case pushes enough arrows.â €

Robin scratches his head. Friar Tuck says Robina € ™ s selection process is straight arrows (raw) holding the bow steady and gently release the cord (human factor), the wood of the bow and the force of the chain (machinery), and the technique of focus the process in the bubble ™ € s (eye calibration and statistical process control).

The product of Robina € ™ s process is an arrow on target. More specifically, products that satisfy customers are the arrows that score. The arrows outside the circle in the third target of nâ € ™ T, which are defects. Robina € ™ s process seems to be 100% compatible with the specifications. In other words, any product made is acceptable to the customer.

â € œYou think three fifty-seven Sigma Archer, â € the monk continues. â € œWeâ € ™ d have to measure many more holes to be sure, but Leta € ™ s assume that 99.99% of the score of their plans, urging € ™ re four sigma € shooter.â Robin tell their gay men progress.

The next day, the wind is changing direction, there is a light fog. Robin believes that feels a cold. Despite of the reason, the process doesn € ™ t stay focused on the environment as it did before. In fact, it is up to 1.5 unpredictable Sigma and other means. Now, instead of producing any default, after a hundred photographs, Robin has been a defect, a hole outside the third circle. In fact, instead of 99.99% scoring strokes are only 99.38%.

While this may not seem like much has changed, Imagine that instead of shooting at targets, laser Robin-drilling holes in the blades of the turbine. Leta € ™ s say there were 100 holes in each sheet. The likelihood of producing even a defect-free sheet not be good. (Due to the creation of defects is random, the process will produce some good waves and a few sheets with multiple defects.)

No time to inspect many more (not including spending an enormous amount to rework and the substances released), Robin, laser drilling, would be almost impossible to find every time even a series of turbine blades with holes drilled correctly.

Not only the four sigma producers have to spend time and money to find and correct defects before products can be shipped, but since the inspection can not find bugs, but also solve the problems when is
the client. The producers of Six Sigma on the other hand, would be able to concentrate on only a handful of flaws to further improve the process.

How tools help Six Sigma quality? If Robin Archer had to use these tools to become a Six Sigma sniper instead of four-drawer Sigma when left in the wind and rain, yet would make all
The score ranges. Some arrows may now be in the second circle, but all still be acceptable to the client, securing the first prize. Rob also the laser drilling would be successful, it would almost by default turbine blades Free.

The steps on the path of Six Sigma Quality:
1. Measure
Quality Six Sigma aims to achieve a standard error businesswide to minus 3.4 per million opportunities to make a mistake.
This quality standard includes the design, manufacture, marketing, administration, service, support € "All facets of the business. Everyone has the goal of equal quality and essentially the same method to achieve this. Although the implementation of the design and engine manufacturing is clear, the objective of Six Sigma PERFORMANC € "and even more TOOLSIE €" also apply to milder more processes.

After the improvement project has been clearly defined and delimited, the first element in the process of improving quality is the measure performance. It demands that effective measures having an overview of statistics on all processes and problems. This reliance on facts and logic is essential for continuation of the Six Sigma quality.

The next step is knowing what to measure. Determine the level of Sigma is mainly based on the defects of the bill, we must measure the frequency of defects. Errors or defects in any manufacturing process tend to be relatively easy to define € "simply the inability to comply with specifications. To extend application to other processes and further improve manufacturing, a new definition is useful: a defect is any failure a requirement for customer satisfaction and the customer is always the next person in the process.

In this first phase, you must select the essential features quality that you expect to improve. These are based on an analysis Your Customerâ € € ™ s requirements (usually using a tool like Quality Function Deployment.) After its clearly defined performance standards and validate their measurement system (with the reliability and repeatability studies Gage), then is able to determine the processing capacity in the short term and long term performance of real processes (Cp and Cpk).

2. Analysis
The second step is to define performance targets and identify sources of process variation. As a company we have implemented Six Sigma performance all processes in the five years since our purpose. This should lead to specific objectives in each operation and process. Identifying sources of variation, after accounting for the defects, we must determine when, where and how they are produced. Many tools can be used to identify the causes variation that creates defects.

Included tools that many people have seen before (process mapping, Pareto charts, diagrams edge Fish, histograms, scatter diagrams, run charts) and some (who may be new affinity diagrams box plots and whiskers, the multivariate analysis, hypothesis testing).

3. Improvement
This phase consists in identifying the possible causes of changes and discover the interrelationships between them. (The common tool in this phase is the design experience or DOE.) Understanding these complex relationships, also allows adjustment of individual process tolerances that interact to produce the desired result.

4. Control
In the control phase, the process of validation of the measurement system and the capacity assessment is to demonstrate that the improvement occurred. Steps are taken to control the improvement process. (Examples of tools used in this phase are the statistical process control, testing error and internal quality audits.)

Words of wisdom about the quality
If you think it is natural to be flawed, and that quality is to find and correct defects before they reach the customer, you're expecting to go bankrupt. To improve the speed and quality, you must first measure ITA € "and must use a common measure.

The company scale common measuring drive quality improvement are the defects per unit of labor and cycle time per work unit. These measures also apply to the design, production, marketing, service, support and administration.

Each is responsible for the quality of production, therefore each must be measured and responsible quality. Measuring quality in an organization and behavior improvement rates aggressively is the responsibility of operational management.

Customers want on-time delivery, product works immediately and not a failure early in life and a product that is reliable in your life. If the process that allows defects, the customer can not easily be saved from themselves by inspection and testing.

Robust design (which is within the capabilities of existing processes to produce) is the key to increasing customer satisfaction and reduce costs. The road to a robust design is through simultaneous engineering and process integrated design.

Because the improvement of quality ultimately reduces the cost, highest quality producer is best suited to be the producer to reduce costs and therefore more effective competitor in the market.

About the Author

Steven Bonacorsi is a Senior Master Black Belt instructor and coach. Steven Bonacorsi has trained hundreds of Master Black Belts, Black Belts, Green Belts, and Project Sponsors and Executive Leaders in Lean Six Sigma DMAIC and Design for Lean Six Sigma process improvement methodologies.

Bonacorsi Consulting, LLC.
Steven Bonacorsi, President
Lean Six Sigma Master Black Belt
14 Clinton Street
Salem NH 03079
sbonacorsi@comcast.net
603-401-7047

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