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 matrix organization isn''t working, Your company's matrix organizat...

Your company's matrix organization isn't working; decisions are taking too long and it seems to you that instead of best solutions you're getting compromises. As CEO what would you

Explain what do you need to be a manager, What do you need to be a manager?...

What do you need to be a manager? What is the most difficult?

Explain what is the horizon value, Current and projected cash flows for Ran...

Current and projected cash flows for Randell Global Operatons are shown below. Growth is expected to be constant after 2012, and the weighted average cost of capital is 11%. What i

Explain is cloud computing the right direction, 1.) Why has Amazon.com succ...

1.) Why has Amazon.com succeeded online when so many other companies have failed? 2) Whats next for Amazon.com? Is cloud computing the right direction for the company? 3.) W

Quantitative layout analysis, Quantitative Layout Analysis Once a layo...

Quantitative Layout Analysis Once a layout is prepared, before accepting it should be evaluated quantitatively and compared with other alternative layouts to have a better lay

Determine the supply and aggregate supply curve , In the food processing se...

In the food processing sector of a country, 100 identical small firms produce frozen fruits. Each producer is a price-taker in the market and faces the following cost conditions:

Explain marketing decisions without marketing research, Is it possible to m...

Is it possible to make sound marketing decisions without marketing research? What advantages does research offer to the decision maker over seat-of-the-pants decision making?

Define strong technical skills or strong communications, What types of peop...

What types of people have more difficulty being team players? What helps promote good team player behaviour? 3. What do you think is more important for a good IT professional: stro

Find forecast energy use for spring, An Electric Company estimates its dema...

An Electric Company estimates its demand trend line (in millions of kilowatt hours) to be D = 79 + 0.52 Q, where Q refers to the sequential quarter number and Q=1 for winter 2000.

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