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## Process capability

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**Process capability**Premiered by EDOUARD GATETE of The Pennsylvania State University.**Overview**• Definition • Measurements of process capability control • How can Process Capability be used in an organization**Overview**• A real world example • Exercise • Summary**Definition**• Process capability is defined as a how likely a product is going to meet the design specification. • It has been argued whether the specifications are actually set by customers or design engineers.**Measurements of process capability**• Most of the times, conventional process capability work quite well, but we have to keep in minds that they will be times when the usual formulas don’t work. • An index that measure potential process capability is used in unusual situation.**Measurements of Process Capability**• The formula C sub P is the tolerance divided by six standard deviations (also known as sigma) • C sub P = tolerance/6-sigma Reveals how many six-sigma fits within a specified tolerance In order for a product to meet specifications, at least 99.773% of productions should confirm anticipated operation condition.**Measurement of process capability**• Population : a collection of all observation of interest to a decision maker. • Sample: a portion of population • population distribution: a distributions of the entire population • sampling distribution: distributions of sample means.**How to use process capability in an organization**• The control chart • bell-shaped curve: as long as all inputs to a process remain constant, the output will always vary**The difference between Stable and capability**• A process is capable if a given product meets specifications. • A process is stable if there is a common variation present in the process**The disadvantage of using process capability**• Over-correcting: the most common • reducing variation**Factors influencing the tolerance allocation**• Statistical aspects of the dimensions and manufacturing processes involved • Assembly requirements and conditions • the cost-tolerance relationship • International Standards Organization's practices for fits.**A real world example**• Taking an example of a car manufacture company. The process capability will be used if out of 1000000 cars produced, only 3.4 cars come out defective**Exercise**• A certain manufacturing process is producing metal washers that have diameters that are known to be normally distributed with mean 1 inch and standard deviation .006 inch. The process is known to be stable and in control. The specifications for these washers are 1 inch +/- .01. What percentage are within specification limits?**Summary**• We have just reviewed process capability. This process is used in production to determine whether a product meets specification on a consistent basis. Even though they are a lot of complex ways to to figured out process capability, it’s more important to understand the basics before we can get in more details.**summary**• This presentation has definitely focused on the basics of process capability. It is very important to minimize defects in production if you want to optimize the profit.**summary**• A bibliography used to come up with these slides is as follow; • Hart, M. Quality Tools for Decreasing Variation and Defining Process Capability. V33 n2. Second Quarter 1992, p.6-11.**summary**• Raouf, A. On developing optimal process capability index. International Journal of Quality & Reliability Management. V9 n7. 1992. P. 17-22 • Bothe, D. R. Measure process capability when Cp won’t work. Quality. V34 n8. Aug 1995. P. 20-22**Summary**• Foster, T. S. An integrative approach. Managing Quality 2001. P. 374-376.