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

Compare the traditional and matrix organization, Compare and contrast the t...

Compare and contrast the traditional and matrix organization. What are its advantages and disadvantages of the matrix organization?

Performance measures - operation strategy, Performance Measures - Operation...

Performance Measures - Operation Strategy It is common to find that measures are made of operational factors which do not contribute to the winning of orders, whilst key facto

Explain confidence interval calculator, Practical Application Scenario 1 To...

Practical Application Scenario 1 To complete this scenario, use the Confidence Interval Calculator and the Area Gas Prices - Random Sample documents, provided in the resources. The

Explain score for energy cost increases, Daniel Tracy, owner of Martin Manu...

Daniel Tracy, owner of Martin Manufacturing, must expand by building a new factory. The search for a location for this factory has been narrowed to four sites: A, B, C and D. The f

Business organisation functions, ''OPERATIONS MANAGEMENT IS THE CENTRAL TO ...

''OPERATIONS MANAGEMENT IS THE CENTRAL TO THE FUNCTIONING OF ALL BUSINESS ORGANISATIONS''.with reference to the organisation of your choice discuss this statement highlighting how

Explain productivity change for labour and investment, Charles Lackey opera...

Charles Lackey operates a bakery in Idaho Falls, Idaho. Because of its excellent product and excellent location, demand has increased by 25% in the last year. On far too many occas

Explain competitive and profitable, How would you respond to Coca Cola's ch...

How would you respond to Coca Cola's change in sales policy? How would you ensure Pepsi's board that this response will allow you to remain competitive and profitable?

Explain how you would influence your family to understand, Discuss the impo...

Discuss the importance of influence. How you would attempt to apply it to convince your team to work an extra day per week to earn time off later. Analyze how you would influence y

How efficient is your system with the cycle time you compute, A firm uses a...

A firm uses a serial assembly system and needs answers to the following- a. A desired output of 900 units per shift (7.5 hours) is desired for a new processing system. The syst

Vogel approximation methods, Vogel Approximation Methods ( VAM): Step...

Vogel Approximation Methods ( VAM): Step 1: For each row the transportation table identify the smallest and next to smallest cost. Determine the different between the

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