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 what additional facts could cause the decision, Ema graduated from ...

Ema graduated from a very prestigious college and was in her second year of medical school. Ema's parents did not have the resources to help her pay for college. For the past six y

Ans, What do you understand by “line balancing”? What happens if balance do...

What do you understand by “line balancing”? What happens if balance doesn’t exist?

Impact of multinational enterprises to their firm boundaries, Multinational...

Multinational enterprises (MNEs) have an impact far beyond their firm boundaries. Assume you are working for a small firm that supplies a product or service to an MNE. How might yo

Explain xerox customer-service teams, When it comes to how a team is design...

When it comes to how a team is designed (i.e., members, communication, goals, norms, etc.) and team leadership, which of the following statements is most true based upon the studie

Explain project procurement management, When concerned with project procure...

When concerned with project procurement management regarding a project, list the different steps of the supply process and reasons why or why not the project would have been more s

Explain shipment to foreign markets, A U.S. manufacturer that exports goods...

A U.S. manufacturer that exports goods made at its U.S. plants for shipment to foreign markets

Manufacturing process technology, eloberate manufacturing process technolog...

eloberate manufacturing process technology with its types. project,jobshop,batch,assembly line,contineous..?

Level capacity plan, Level Capacity Plan The inventory size is varied ...

Level Capacity Plan The inventory size is varied keeping the workforce size and utilization of work constant. The number of workers ( working size) is kept constant throughout

Explain what is the role of participation in goal setting, What is the role...

What is the role of participation in goal setting? Answer Participation is positively correlated with performance Participation provides more goal clarity Participation

Explain why do companies that advertise their csr policies, 1. Why do compa...

1. Why do companies that advertise their CSR policies so often face serious controversies anyway 2. Identify an area in which Apple is regarded as responsible to a stakeholder

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