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

Explain type of marketing research, Obtaining data on the number of househo...

Obtaining data on the number of households that buy a particular product is an example of which type of marketing research? Explanatory Exploratory Causal Concrete

Explain guidelines for how management should be treating emp, Which of the ...

Which of the following responsibilities do human resource managers fulfil in their role as employee advocates? A) provide support for employees contesting unfair practices B) provi

Explain concepts in the world of marketing, In the world of marketing, ____...

In the world of marketing, _____ are ideas about products or services. (Points : 3) concepts notions perceptions impressions theories

Explain writing the final case study and strategic plan, Read the Starbucks...

Read the Starbucks Global Quest 2006: Is the Best Yet to Come? Case provided in the Course Materials section. From the perspective of an executive with the firm, prepare a 10-12 pa

Introduction, what is production and operation management?

what is production and operation management?

Explain reliability required for each component equals, A new aircraft cont...

A new aircraft control system is being designed that must be 98.0% reliable. This system consists of three components in series. If all three of the components are to have the s

Explain what would be the danger of your hospital, Assume you are the respo...

Assume you are the responsible senior executive of a hospital in a city with a population of 30,000 people, located about 50 miles away from a large city. What would be the danger

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

Answer, A paper mill produces two grades of paper viz., X and Y. Because of...

A paper mill produces two grades of paper viz., X and Y. Because of raw material restrictions, it cannot produce more than 400 tons of grade X paper and 300 tons of grade Y paper i

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