SBS - The Best Value in QMS software

PPK, CPK of >= 1.67 Automotive Requirement and Auditing

Q

qualityboi

#1
What are your comments regarding a Cpk level of 1.67 as a requirement of the ISO/TS 16949 Standard or Automotive industry?

Background: Discussion is among quality managers in my company (we have 6 of them at last count). There is some discussion that the 1.67 cpk level must be strived for in "critical" processes, critical meaning those processes have special or critical measurements in the control plan.
Should the Cpk level be strived for anyway as an "unstated requirement" of the automotive industry? How do you define as "communicated by the customer"? Is this in a contract form, a verbal comment by the customer's supplier quality engineer during a supplier audit (either)?
Do you ever write up a non-conformance when a critical process is not equal to or exceeding a Cpk of 1.67? If you were going to write them up would you still do it even if they had improvement plans to get there?

Thanks
 
Elsmar Forum Sponsor

bobdoering

Stop X-bar/R Madness!!
Trusted Information Resource
#2
What are your comments regarding a Cpk level of 1.67 as a requirement of the ISO/TS 16949 Standard or Automotive industry?
Demonstrating capability is a PPAP requirement. Either you identify your process is stable and capable (PPAP 2.2.11.3), or deal with the customer on unstable processes (PPAP 2.2.11.4 and 2.2.11.6).

Pay close attention to PPAP 2.2.11.5 concerning one-sided specifications and non-normal distributions!!!

There is some discussion that the 1.67 cpk level must be strived for in "critical" processes, critical meaning those processes have special or critical measurements in the control plan.
Not "strived"...met and maintained.

The requirement states "Special Characteristics designated by the customer or organization (you)"

If the customer's print does not cite special characteristics, the customer reserves the right to require capability on other characteristics. And, of course, any characteristics you identify as special (or critical, if you will) will need to show capability.

Note it states special characteristics, it does not specify anything about "special processes".

Should the Cpk level be strived for anyway as an "unstated requirement" of the automotive industry? How do you define as "communicated by the customer"? Is this in a contract form, a verbal comment by the customer's supplier quality engineer during a supplier audit (either)?
The requirement is it must be met for special characteristics - whether the customers or yours. It is "stated", actually (PPAP 2.2.11.3)

How do you define as "communicated by the customer"? Is this in a contract form, a verbal comment by the customer's supplier quality engineer during a supplier audit (either)?
Should be identified with a special character on their print.

Do you ever write up a non-conformance when a critical process is not equal to or exceeding a Cpk of 1.67? If you were going to write them up would you still do it even if they had improvement plans to get there?
Yes. If it is not capable, you must develop a corrective action (TS 16949 8.2.3.1) - not improvement plan, including containment and 100% inspection as appropriate. :cool:
 
Thread starter Similar threads Forum Replies Date
C Capability in sewing processes CP,CPk,PP,PPk Capability, Accuracy and Stability - Processes, Machines, etc. 10
W LTPD, AQL, Ppk and Cpk validation sampling plan table Inspection, Prints (Drawings), Testing, Sampling and Related Topics 0
A Interpretation with regards to Ppk > Cpk Capability, Accuracy and Stability - Processes, Machines, etc. 14
E SPC Production - Getting Cpk and Ppk Statistical Analysis Tools, Techniques and SPC 8
V When to use Cp Cpk and Pp Ppk Capability, Accuracy and Stability - Processes, Machines, etc. 4
S Value of Ppk or Cpk when targeting thinner material Statistical Analysis Tools, Techniques and SPC 4
B Cpk vs Ppk to look at the Capability by Fixture Capability, Accuracy and Stability - Processes, Machines, etc. 4
V Customer requires CpK 2 and PpK 1.5 Capability, Accuracy and Stability - Processes, Machines, etc. 2
R Which of the following indicators is important for Operations - Ppk, Cpk, or Cpm? Statistical Analysis Tools, Techniques and SPC 15
U Cpk and Ppk for different Countries/Standards Capability, Accuracy and Stability - Processes, Machines, etc. 7
B Understanding why my CpK and PpK are low, and LCL Statistical Analysis Tools, Techniques and SPC 20
S Which one is better to calculate, Cpk or Ppk? Statistical Analysis Tools, Techniques and SPC 11
A How to calculate Cpk & Ppk if the tolerance changes during the period? Capability, Accuracy and Stability - Processes, Machines, etc. 5
B Formula Data Validation Set for Cp, Cpk, Pp & Ppk Capability, Accuracy and Stability - Processes, Machines, etc. 1
F Please share an MS Excel sheet to calculate Cpk and Ppk Statistical Analysis Tools, Techniques and SPC 1
R Ppk vs Cpk: Big Differences - What conclusion can I reach about my process? Six Sigma 3
A How to interpret Minitab Results? What is difference in Cpk and Ppk values? Using Minitab Software 2
J Cpk & Ppk - Reviewing a PPAP Package - Some questions Statistical Analysis Tools, Techniques and SPC 8
S Ppk & Cpk - Within Subgroup Variation is always smaller than Total Variation Capability, Accuracy and Stability - Processes, Machines, etc. 18
V CNC Process Validation Cpk Ppk & In-Process Inspection Inspection, Prints (Drawings), Testing, Sampling and Related Topics 7
S Pp/Ppk & Cp/Cpk - Which is appropriate for Long/Short Term Study? Statistical Analysis Tools, Techniques and SPC 20
R Cpk & Ppk and Differences between Minitab and an Excel Spreadsheet Results Statistical Analysis Tools, Techniques and SPC 4
S How is Cpk /Ppk value calculated in Minitab since I have subgroup size of 1 Capability, Accuracy and Stability - Processes, Machines, etc. 1
Q When to use Cpk or Ppk for a Process Capability Study? Capability, Accuracy and Stability - Processes, Machines, etc. 14
A Deciding on when to go for Cp & Cpk or Pp & Ppk Study? Statistical Analysis Tools, Techniques and SPC 3
C Understanding the relationship of Pp, Ppk, Cp, Cpk Six Sigma 4
S Cpk and Ppk Differences and Questions Capability, Accuracy and Stability - Processes, Machines, etc. 5
E Cpk and Ppk template wanted Capability, Accuracy and Stability - Processes, Machines, etc. 3
Q ASQ CSSBB Question on Cpk and PPk , can you solve it ? Capability, Accuracy and Stability - Processes, Machines, etc. 15
M Calculation of Cpk and Ppk for an unstable process Statistical Analysis Tools, Techniques and SPC 7
P Individual & MR chart - Ppk or Cpk? Capability, Accuracy and Stability - Processes, Machines, etc. 9
K Normality of distribution prior to Cpk and PpK Statistical Analysis Tools, Techniques and SPC 4
R Can Ppk value be greater than Cpk and if yes, under what conditions? Statistical Analysis Tools, Techniques and SPC 10
C Is it possible to get Pp,Ppk more than the within subgroup (Cp,Cpk's) indices? Statistical Analysis Tools, Techniques and SPC 7
S Are Pp and Ppk more useful than Cp and Cpk as a benchmark for further studies? Statistical Analysis Tools, Techniques and SPC 1
J Using Pin Gages as a Measurement Tool for Ppk/Cpk studies Capability, Accuracy and Stability - Processes, Machines, etc. 11
B Difference between Ppk (Preliminary), Cpk, Performance Capability Statistical Analysis Tools, Techniques and SPC 2
D Real life example of the difference between Cpk and Ppk Capability, Accuracy and Stability - Processes, Machines, etc. 0
N Cpk vs Ppk - Which should you use and How to Calculate Cpk and Ppk Statistical Analysis Tools, Techniques and SPC 25
V Quality Control Index - We thought that Cpk or Ppk would be good choices Capability, Accuracy and Stability - Processes, Machines, etc. 6
Tim Folkerts Interpreting the common capability indices: Cp, Cpk, Pk, and Ppk. The Reading Room 5
J Machine issue in Cpk/Ppk and Control Plan - PPAP Submissions APQP and PPAP 5
D Use of an outlier in calculating Cpk/Ppk Capability, Accuracy and Stability - Processes, Machines, etc. 8
N Analysis of non-normal stratified data for cpk/ppk? Rupture test Capability, Accuracy and Stability - Processes, Machines, etc. 6
F Ppk/Cpk value with 1-sided specification - Only given a lower specification Statistical Analysis Tools, Techniques and SPC 1
S Ppk/Cpk for geometrical true position of hole with MMC Capability, Accuracy and Stability - Processes, Machines, etc. 17
Howard Atkins Validation of Cpk and Ppk calculations - Sheet to check Cpk and Ppk values Statistical Analysis Tools, Techniques and SPC 4
S What is the meaning of "k" in Cpk and Ppk? And Cpk vs. Ppk Capability, Accuracy and Stability - Processes, Machines, etc. 15
A Capability Indexes for ISO/TS16949 - Cpk & Ppk after PPAP Statistical Analysis Tools, Techniques and SPC 6
C I need help verifying formula's in a database for LCL UCL Cp Cpk PPk Statistical Analysis Tools, Techniques and SPC 14

Similar threads

Top Bottom