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 why can''t i read my textbook, Why can't I read my textbook? Every ...

Why can't I read my textbook? Every time I click the link "Read Now" a box pops up telling me the Privacy Policy. I have no way of agreeing to the policy, it just states all the ru

Process based layout, Process Based Layout In this layout machines and...

Process Based Layout In this layout machines and services are grouped on a functional basis operation of the same type are performed in the same area. For example all welding

Process focused production system, Process Focused Production System Th...

Process Focused Production System This is a form of production system in which production operations are grouped according to the type of process. In other words, all productio

Compute productivity indices and compare rises productivity, 1. Productivit...

1. Productivity is considered by many to be the essence of operations management - suggest reasons to support this assertion.  2. Using the figures in the table, if we use 2000

Manufacturing process technology, Manufacturing Process Technology New...

Manufacturing Process Technology New products are not physical realities until are manufactured. Process technology refers to the equipment, people and systems used to produce

Describe why financial objectives essential for the company, Why do financi...

Why do financial objectives essential for the company to succeed?

Explain how effective are actions by project managers, Provide two examples...

Provide two examples of current leaders and describe how they demonstrate their leadership characteristics. What separates these characteristics from management techniques? How eff

Managing organizational change, Applying models and concepts from the cours...

Applying models and concepts from the course, analyze a significant change initiative you have observed, have been affected by or have had a hand in implementing in your organizati

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