Cpk or Ppk in packaging closure manufacturing?

E

Ends

#1
#1
I am a Quality Manager in a closure/end manufacturing facility. Our products are used on products such as composite cans for powdered beverage and peanuts. The Cpk/Ppk is a vital measurement that our company lives and dies by. We currently use DataMyte collection systems and run Turbo SPC, a dos based program. Here recently, I pulled raw data out of Turbo and transfered it over to Minitab. After doing this, I discovered that Turbo's Cpk was the Ppk in Minitab. Many of our customers want Cpk reports for the products they are receiving. But our company wants long term capability, Ppk. As I understand, Ppk makes an assumption on what you will do long term if you make no changes. Is this correct? Our process involves metal stamping, we change dies and die components on a certain number of strokes. Therefore, we are consistently makes changes from month to month. What would be the best measurement to use in this type of manfacuring?
 
Standard Work Instruction Software by Dozuki
Elsmar Forum Sponsor
A

Al Dyer

#2
#2
Cpk is used when historical data shows the process to be stable. It is based on using a sample standard deviation.

Ppk is used when a process is chronically unstable but showing a predictable pattern. It is based on the standard deviation of not the sample size, but of all the individual samples.

Your company needs to base its decisions on the above criteria and as always give the customer what he wants. Most software programs today have an option to report either or both of these measurements. One can be used internally and one can be used for the customer.

ASD...
 
You must log in or register to reply here.
Thread starter Similar threads Forum Replies Date
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
Sean Kelley 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
Barahir 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
Q PPK, CPK of >= 1.67 Automotive Requirement and Auditing IATF 16949 - Automotive Quality Systems Standard 1
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. 15
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
S Calculating Cpk/Ppk Simultaneously in SPC software Capability, Accuracy and Stability - Processes, Machines, etc. 6

Similar threads

Top Bottom