Ford CSR Cpk/Ppk Requirements

[dave.d]

In Ford's CSR there is a table titled "Ongoing Process and Product Monitoring" which defines a process as being in control if the Ppk is "Equal to or Greater than 1.33."

While looking at the prior CSR (2008) I found a table with the same title which is formatted in a very similar manner. In that table there is no reference to Ppk, but Cpk instead.

In the older CSR "Cpk" is preceded by the words "Historical Process Capability."

In the new CSR "Ppk" is preceded by the words "Process Capability."

Has anyone been in a position to discuss this with an auditor or Ford? If so I'm curious how that went.

Thank you,

Dave

 

[Matt Savage]

Are you looking to know why the focus is on Ppk (now) instead of Cpk?

 

[AMIT BALLAL]

@dave.d , there was a mistake in old CSR which is now corrected.

 

[dave.d]

Any idea why are they referring to Ppk as Process Capability instead of Process Performance?

 

[AMIT BALLAL]

Any idea why are they referring to Ppk as Process Capability instead of Process Performance?

I didn't find anywhere in the CSR about Ppk being called "Process capability". Ford mentioned it as "Ongoing production process capability", keeping "performance index" in bracket.

Here is a snapshot of the same.

 

[Matt Savage]

If this helps, the SPC Reference Manual by AIAG (Automotive Industry Action Group) lists:
Cpk - The capability index for a stable process ... and
Ppk - The performance index ...

 

[dave.d]

I'm looking at "Table-A - Ongoing Process and Product Monitoring," on page 40 of the March 2017 release.

 

[Bev D]

Welcome to sloppy language and fungible definitions…at least the table does specify Ppk and not leave it up to the reader to determine waht is meant.

 

[Enghabashy]

Cpk still measure the accuracy , ppk still measure the performance , both are essential

 

[Jason Baur]

In Ford's CSR there is a table titled "Ongoing Process and Product Monitoring" which defines a process as being in control if the Ppk is "Equal to or Greater than 1.33."

While looking at the prior CSR (2008) I found a table with the same title which is formatted in a very similar manner. In that table there is no reference to Ppk, but Cpk instead.

In the older CSR "Cpk" is preceded by the words "Historical Process Capability."

In the new CSR "Ppk" is preceded by the words "Process Capability."

Has anyone been in a position to discuss this with an auditor or Ford? If so I'm curious how that went.

Thank you,

Dave

I am meeting with my STA manager now regarding the transfer of work from one location to another. CPK is not used by Ford in his judgement. He said that this changed recently. He challenged me to look it up in the CSR. I did so and he is correct they use PPk of 1.67 for initial and PPk of 1.33 for long term. Makes no sense to me because they are different formulas. All industries outside automotive use PPK for long term and CPK for short term but the formulas are also inverted so it essentially is the same.