Process capability index - asymmetrical positioning, Operation Management

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

Posted Date: 3/16/2013 1:29:37 AM | Location : United States







Related Discussions:- Process capability index - asymmetrical positioning, Assignment Help, Ask Question on Process capability index - asymmetrical positioning, Get Answer, Expert's Help, Process capability index - asymmetrical positioning Discussions

Write discussion on Process capability index - asymmetrical positioning
Your posts are moderated
Related Questions
Making Better Business Decision: Do you provide the quizzes/exams questions for this book?

Discuss the impact of social networking in computing today, and in the future five years

Assess the importance of completing post-project reviews, and determine what project documentation must be updated as the result of the review meeting. Discuss the risks associated

Analyze the characteristics of a successful entrepreneur and determine if you have what it takes to start your own business. Provide specific examples to support your response.

Creating diverse teams is a challenge. All of the following are important steps to include in a plan for bringing diversity to a team, except: a. The organization should publicly c

Southern Fresh has decided to make a policy that every product will receive enough shelf space to ensure that 98.75 percent of customers will find that their first choice is availa

Define all the steps included in collective bargaining process. The steps included in collective bargaining process are:- (i) Putting up before the management, through th

I have a take home exam that I need to be solved 100 % correct , please . I need it within 23 hours EXACTLY from now please . Thank you so much and I am really looking forward to s

1. Why is some knowledge of accounting necessary to succeed in business? Provide examples. 2. Name some of the major stock exchanges where securities are traded. Describe the ch

Electronics assembly operates two 8 hours shifts for 275 days per year. Use this information in the table to determine the capacity requirements. Cell Phone Demand forecast (phones