The Elsmar Cove Business Standards Discussion Forums More Free Files Forum Discussion Thread Post Attachments Listing Elsmar Cove Discussion Forums Main Page
Welcome to what was The Original Cayman Cove Forums!
This thread is carried over and continued in the Current Elsmar Cove Forums

Search the Elsmar Cove!

Wooden Line
This is a "Frozen" Legacy Forum.
Most links on this page do NOT work.
Discussions since 2001 are HERE

Owl Line
The New Elsmar Cove Forums   The New Elsmar Cove Forums
  Statistical Techniques and 6 Sigma
  More GD&T

Post New Topic  Post A Reply
profile | register | preferences | faq | search

UBBFriend: Email This Page to Someone! next newest topic | next oldest topic
Author Topic:   More GD&T
Lurker (<10 Posts)

Posts: 7
From:Cochran, GA, USA
Registered: Jul 1999

posted 12 August 1999 11:21 AM     Click Here to See the Profile for Tim   Click Here to Email Tim     Edit/Delete Message   Reply w/Quote
Ok guys. This one really baffled me. I was in a meeting with our vendor when the program manager said. We can't compute Cpk using GD&T. (I have since convinced most of them that you actually can, thanks to everyone's input.) He then said but we can compute Cp. I have read some previous posts comparing Cp with Cpk. But I can't for the life of me figure out why you can't (or at least they say you can't) compute Cpk but can compute Cp. Are there any differences that would keep you from making the math work.

IP: Logged

Forum Contributor

Posts: 111
From:Kane, PA 16735

posted 12 August 1999 03:02 PM     Click Here to See the Profile for Batman   Click Here to Email Batman     Edit/Delete Message   Reply w/Quote
Hi Tim!
GD&T is a common set of rules for creating a part drawing with form, fit, and function in mind. Every part has some limits above and below which you cannot go. These limits are called tolerances.

Cpk (and Cp) is a statistical calculation from [usually a sample of] the actual produced parts comparing that data TO the tolerance on the drawing.

In this order:
Create drawing with tolerances, etc.
Make parts to drawing
Analyze (measure) parts - compute average and sigma
Compare this calculation to the tolerance on the drawing.

IP: Logged

Don Winton
Forum Contributor

Posts: 498
From:Tullahoma, TN

posted 13 August 1999 09:23 AM     Click Here to See the Profile for Don Winton   Click Here to Email Don Winton     Edit/Delete Message   Reply w/Quote
Are there any differences that would keep you from making the math work?

No there are not. Both equations use mean and standard deviation, along with constants (3, 6, USL, LSL, etc.) Since you can determine mean and standard deviation, if you can compute Cp on a variable, you can compute Cpk on the same variable.


Just the ramblings of an Old Wizard Warrior.

Check Out dWizard's Lair:
*** Dead Link Removed ***

IP: Logged

All times are Eastern Standard Time (USA)

next newest topic | next oldest topic

Administrative Options: Close Topic | Archive/Move | Delete Topic
Post New Topic  Post A Reply Hop to:

Contact Us | The Elsmar Cove Home Page

Your Input Into These Forums Is Appreciated! Thanks!

Main Site Search
Y'All Come Back Now, Ya Hear?
Powered by FreeBSD!Made With A Mac!Powered by Apache!