Process Capability (Measure)

Process Capability Index

Based on all batches and the population standard deviation

How does the Black Belt determine Mean shift?

Check the Cp value first, and then the Cpk value If Cp greater than 1 and Cpk is also greater than 1, it indicates the process is capable of performing to customer expectations.

Which one of these activities should ideally come first in the implementation of a Measure stage, normality, precision, repeatability or resolution?

Checking Resolution

What calculations are used for capability in discrete data?

DPMO or PPM

Cpk can have negative values (True or False)

False: Cpk can only have positive values

When is a process fully capable?

It has to at least reach 1.33

How to determine best fit in Non normal capability?

Look at p-value in Goodness of fit test p-value must be greater than 0.010 (p>0.010)

If Cpk=Cp

Mean is centered and process accurate, but need to assess variation

If Cpk<Cp

Mean isn't centered, variation is high

Cpk index

Process alignment-how good process delivers with respect to mean

Cp

Process capability (tolerance)how good process delivers what customer wants

Which tool is typically used for scope in Measure Stage

SIPOC

What is the most important pre-cursor for Capability studies?

Stability

Cpk negative

The process mean exceeds the specification limits

What are common goals set in process capability?

1.33 or 1.67 are commonly set as goals. 1.33 correspond to 4 sigma; 1.67 represents 5 sigma levels.

How are specification limits derived?

From Voice of customer; the customer requirements

Ppk- Process Performance Index

How well process is in delivering what customer wants, over time with respect to Mean in the long run

Pp -Process potential

How well process performs over time with respect to specifications

Process performance indices

Index based on a specific batch and sample standard deviation

CP is always greater than Cpk (True or False)

True

True/False: Cpk, Cp cannot be used for Discrete data

True

Cpk cannot be larger than Cp (true or false)

True: Cp represents the maximum capability

If Cp or Cpk <1

Variation is high, capability is low and process incapable

If Cp or Cpk>1

Variation is low, capability is high and process is Capable