Process capability index - asymmetrical positioning, Operation Management

Assignment Help:

Process Capability Index - Asymmetrical Positioning of the Process

As stated earlier, the Cp index assumes that the process mean is centred within the tolerance band, but, in practice, this is often an unreasonable assumption. For this reason, alternative indices have been devised which take account of asymmetrical positioning of the process mean relative to mid-tolerance. Consider the process output represented in this next figure, for which the LSL is 10, the USL is 20, the process mean (µ) is 18 and the standard deviation (σ) is 1.166. For this process the Cp index value is 1.43 [i.e. (20 - 10)/ (6 × 1.166)], which might suggest that the output has a very low level of non-conformance. However, as can be seen from the figure, a significant proportion of the output actually lies beyond the upper specification limit. The Cpk index takes account of the asymmetry by relating the spread of one side of the output distribution (3σ) to the difference between the process mean (µ) and the nearest specification limit. Two calculations are performed, and the lowest value (worst case) is taken as the index value.

1148_Process Capability Index – Asymmetrical Positioning of the Process.png

In the example in the figure above, the Cpk index is 0.57 [ie (20 - 18)/(3 × 1.166)], indicating that the process, as currently set, is not capable of producing to the design specification. The following figure shows the significance of different Cpk values.

1302_Process Capability Index – Asymmetrical Positioning of the Process 1.png


Related Discussions:- Process capability index - asymmetrical positioning

Describe potential key changes in communications, Discuss potential key cha...

Discuss potential key changes in technology, communications, and competition that Sigma will face in the future. Which will have the most impact on Sigma%u2019s future marketing st

Calculate first''s rop, First printing has contracts with legal firms in Sa...

First printing has contracts with legal firms in San Francisco to copy their court documents. Daily demand is almost constant at 12,500 pages of documents. The lead time for paper

Explain mechanical license hand-out, Find a cover song from one of your CD'...

Find a cover song from one of your CD's. If you have no CD, use one from the library. Looking at the credits & using the Mechanical License hand-out as a reference, submit the foll

What does mean owns real estate in fee simple absolute, If someone owns rea...

If someone owns real estate in fee simple absolute, what does that mean?

Describe case studies with ethnographic research, 1. What benefits can be g...

1. What benefits can be gained from case studies? What dangers, if any, are there in using case studies? In what ways are they useful? Support your answers. 2. Provide some exam

Competence - customer satisfaction and service quality, Competence - Custom...

Competence - Customer Satisfaction and Service Quality Means possession of the required skills and knowledge to perform the service. It involves: knowledge and skill of the c

Explain industrial relations, Explain Industrial Relations. Industrial...

Explain Industrial Relations. Industrial Relations: it is that aspect of management that deals with the manpower of the enterprises where machine operators, skilled managers

Explain employees effectively execute the strategy, Select a company that y...

Select a company that you believe uses its employees to achieve a competitive advantage. Discuss how the employees effectively execute the strategy and how the company can sustain

Implications for operations manager - operations functions, 1. Reflecting o...

1. Reflecting on McGroddy's comments - what are the implications for the operations manager? Answer: The point to note here is that organisations resist change. It suggests that

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd