what is cpk? - quality digest · why use cpk? • in the supply chain –cpk is a standard way for...
TRANSCRIPT
![Page 1: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/1.jpg)
![Page 2: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/2.jpg)
What is Cpk?
• A statistic
• Simple to calculate
![Page 3: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/3.jpg)
Why use Cpk?
• Cpk can answer this question:
– Are we able to meet customer requirements?
![Page 4: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/4.jpg)
Why use Cpk?
• More specifically:
– Can our system produce consistently within
tolerances required by the customer now and
in the future?
![Page 5: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/5.jpg)
Why use Cpk?
• In the supply chain
– Cpk is a standard way for producers and
consumers to communicate about quality
levels.
![Page 6: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/6.jpg)
What is a good Cpk value?
• Your customer has a requirement for Cpk.
• A higher number is better; reduced risk of delivering a product that is out of tolerance.
• A Cpk of 1.0 is considered “capable.” Your customer may require 1.33 or 1.66.
![Page 7: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/7.jpg)
Fully understand Cpk
• Facts are stubborn things, but statistics are
pliable.
• Mark Twain
![Page 8: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/8.jpg)
![Page 9: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/9.jpg)
![Page 10: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/10.jpg)
Fully understand Cpk
![Page 11: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/11.jpg)
![Page 12: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/12.jpg)
![Page 13: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/13.jpg)
Fully understand Cpk
![Page 14: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/14.jpg)
Understand what your customer needs
• Once you fully understand Cpk and
Capability analysis…
• Seek to understand what your customer
needs.
![Page 15: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/15.jpg)
Understand what your customer needs
![Page 16: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/16.jpg)
Understand what your customer needs
• Potentially thousands of characteristics…
• Which ones are critical?
“One that is both important to your customer and difficult to produce consistently within the specifications.”
Donald Wheeler, Ph.D.
![Page 17: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/17.jpg)
Study what your current system can do
• Ensure process is in-control, predictable, stable (using control chart)
– Alternative definition of SPC:• Stability, Predictability, then Capability
• Perform capability analysis on critical characteristics
![Page 18: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/18.jpg)
Study what your current system can do
• Specification limits:– The voice of the customer
• Control limits:– The voice of the process
“There is no logical connection between control limits and specifications.”
– Dr. W. Edwards Deming
![Page 19: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/19.jpg)
Customer needs vs. your capability
• Increasing Cpk
Customer needs Your capability
Cpk 1.33 or higher Cpk = 0.96
Cpk 1.0 or higher Cpk = 1.17
![Page 20: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/20.jpg)
Your capability is less than customer needs…
• Steer the process average to the Target
![Page 21: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/21.jpg)
Your capability is less than customer needs…
• Reduce variation
![Page 22: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/22.jpg)
Your capability is less than customer needs…
• Widen tolerances
![Page 23: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/23.jpg)
Your capability is less than customer needs…
• Can you supply
what they need?
![Page 24: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/24.jpg)
When you do meet customer requirements:
• Continue to improve process
• Move from old school to new school
– Old school (category thinking):
• In specs = good
• Out of specs = bad
– New school (continuous thinking):
• Any distance from target is a loss
• Further from target = more loss
• Taguchi Loss Function
![Page 25: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/25.jpg)
Taguchi Loss Function:
Good
Bad Bad
![Page 26: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/26.jpg)
Taguchi Loss Function:
Loss -><- Loss
![Page 27: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/27.jpg)
Taguchi Loss Function:
![Page 28: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/28.jpg)
When you do meet customer requirements:
• Increase:
– Capability mindset among employees
– Scale and speed at which you can assess capability
– Holistic view including measurement system, control, and capability
![Page 29: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/29.jpg)
Tips for improving capability analysis
• Six-Way Analysis – holistic view
![Page 30: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/30.jpg)
Tips for improving capability analysis
• Strive for “at-a-
glance” visuals:
![Page 31: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/31.jpg)
• Capability summary
chart – red means
“bad”
Tips for improving capability analysis
![Page 32: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/32.jpg)
Tips for improving capability analysis
• Key requirement:
Statistically stable
process
![Page 33: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/33.jpg)
Tips for improving capability analysis
• Requirements for a
good control chart:
![Page 34: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/34.jpg)
Tips for improving capability analysis
• Requirements for a
good control chart:
![Page 35: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/35.jpg)
Tips for improving capability analysis
• Requirements for a
good control chart:
![Page 36: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/36.jpg)
1. Fully understand capability analysis
2. Understand what your customer needs
3. Study what your current system can do
4. Compare customer needs with your capability
5. On-going monitoring for system changes
Getting the most from Cpk (Capability Analysis)
![Page 37: What is Cpk? - Quality Digest · Why use Cpk? • In the supply chain –Cpk is a standard way for producers and consumers to communicate about quality levels](https://reader031.vdocuments.us/reader031/viewer/2022012312/5b20ff777f8b9a6f6e8b45f1/html5/thumbnails/37.jpg)
Thank you for attending!
Questions?
Matt Savage – [email protected]
Steve Daum – [email protected]
Request the white paper
Cpk: Indispensable index or misleading measure?
www.pqsystems.com/cpkwhitepaper
Get a free trial of SQCpack
www.sqcpack.com