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 the areas needing improvement as a communicator, • From the scenar...

• From the scenarios, we see that Chris and Erica have different communication styles that could potentially have a negative impact on the business. Suggest at least two strategies

What are some new products organizational markets, What are some new produc...

What are some new products I could use that serve two business (organizational) markets?

Flow Time, You know that our average weekly sales are $2,500 and the flow t...

You know that our average weekly sales are $2,500 and the flow time is half day. Surely with this information, you should have no problem maintaining an inventory level of $400 to

Explain major reasons why companies adopt total quality, Discuss the three ...

Discuss the three major reasons why companies adopt total quality. Also, discuss the initial key steps are involved in the adoption process.

Linking strategic & operational change - operation strategy, Linking Strate...

Linking Strategic and Operational Change - Operation Strategy Quinn (1988) criticises those who see strategy formulation and implementation as the 'classic trap' where despite

What are the classified different stock items, What are the classified diff...

What are the classified different stock items? The ABC system of inventory management Various stock items are classified as like: a. High value (A) b. Medium value (B

Describe how laws tie into business ethics, Discuss how laws tie into busin...

Discuss how laws tie into business ethics. Support your ideas with research and specific examples of laws discussed in your text.

Define activity a can be finished and not delay any activity, Using the dat...

Using the data in Table 13-4, determine the latest time activity A can be finished and not delay any activity? Table 13-4 The following represents a project with known activity tim

Explain estimate of the dates of the milestones, You are in charge of organ...

You are in charge of organizing a dinner-dance concert for a local charity. You have reserved a hall which will seat 30 couples and have hired a band. Develop a scope statement for

Define and analyze a best practice human capital acquisition, Identify and ...

Identify and analyze a best practice human capital acquisition, development, and retention in the United Kingdom Please provide references in APA format

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