Skip to main content
Main Menu
  • Capabilities
    Back
    Capabilities
    • Assembly
    • Catheter Design
    • High Purity Specialty Closures
      Back
      High Purity Specialty Closures
      • Closure Assemblies
      • Liners
    • COVID-19 Rapid Manufacturing Capabilities
    • Custom Compounding
    • Custom Filtration
    • Medical Extrusion
    • Medical Molding
    • Prototyping and Tooling
    • Product Co-Development
  • Materials
    Back
    Materials
    • Fluoropolymers
      Back
      Fluoropolymers
      • Basics 101: Fluoropolymers
    • Other Materials
    • Silicone
      Back
      Silicone
      • Basics of Silicone:101
    • Thermoplastics
      Back
      Thermoplastics
      • Basics 101: Thermoplastics
      • PEEK page
  • Markets
    Back
    Markets
    • Cardiology
    • Diabetic Care
    • Drug Delivery
    • Nephrology
    • Ophthalmology
    • Other Medical Markets
    • Surgery
  • Resources
    Back
    Resources
    • Schedule a Lunch and Learn
    • Technical Data and Literature
    • White Papers
      Back
      White Papers
      • Effect of Sterilization on the Mechanical Properties
      • Extruded Silicone Tubing with Optimized Precision for medical device manufacturers
      • Flow Rate Stability of Medical Peristaltic Pump Tubing Materials
      • Liquid Silicone Rubber Injection Molding
      • Low Coefficient of Friction Materials: Tygon® LCF Offers the Ideal Combination
      • The Impact of Gamma and Autoclave Sterilization on Silicone Tubing
      • Two-Shot Silicone-Thermoplastic Medical Molding
    • Quality and Regulatory
      Back
      Quality and Regulatory
      • ISO Certifications
      • Medical Product Disclaimer
    • FAQs
    • Videos
  • About Us
    Back
    About Us
    • Events
    • Blog
    • News
    • Case Study
  • Contact Us
world SAINT-GOBAIN
Logo Saint-Gobain Medical
  • Capabilities
    • Assembly
    • Catheter Design
    • High Purity Specialty Closures
      • Closure Assemblies
      • Liners
    • COVID-19 Rapid Manufacturing Capabilities
    • Custom Compounding
    • Custom Filtration
    • Medical Extrusion
    • Medical Molding
    • Prototyping and Tooling
    • Product Co-Development
  • Materials
    • Fluoropolymers
      • Basics 101: Fluoropolymers
    • Other Materials
    • Silicone
      • Basics of Silicone:101
    • Thermoplastics
      • Basics 101: Thermoplastics
      • PEEK page
  • Markets
    • Cardiology
    • Diabetic Care
    • Drug Delivery
    • Nephrology
    • Ophthalmology
    • Other Medical Markets
    • Surgery
  • Resources
    • Schedule a Lunch and Learn
    • Technical Data and Literature
    • White Papers
      • Extruded Silicone Tubing with Optimized Precision for medical device manufacturers
      • Two-Shot Silicone-Thermoplastic Medical Molding
      • The Impact of Gamma and Autoclave Sterilization on Silicone Tubing
      • Low Coefficient of Friction Materials: Tygon® LCF Offers the Ideal Combination
      • Liquid Silicone Rubber Injection Molding
      • Flow Rate Stability of Medical Peristaltic Pump Tubing Materials
      • Effect of Sterilization on the Mechanical Properties
    • Quality and Regulatory
      • Medical Product Disclaimer
      • ISO Certifications
    • FAQs
    • Videos
  • About Us
    • Events
    • Blog
    • News
    • Case Study
  • Contact Us
COVID-19 Rapid Manufacturing Capabilities – LEARN MORE

You are here

  1. Home
  2. About Us
  3. Blog
  4. Cpk vs Ppk? What Is The Difference and Why It Is Important

Cpk vs Ppk? What Is The Difference and Why It Is Important

March 15th, 2019

Author: Kelly Jakinovich - Medical Extrusion Product Manager

 

Understanding these concepts can be tough when you aren’t regularly working with them. This article is not how to calculate Cpk or Ppk, as there are several resources in print or on the internet to figure that out. Instead this article is intended to explain the difference between the two and why the different calculations are important.

In the short sense, Cpk and Ppk are about process capability and process performance, respectively.

Process capability, Cpk, is important because it indicates whether a process potentially can meet a specification. Essentially, it is a prediction of the ability of a process to meet a specification.

Process performance, Ppk, is important because it indicates how the actual process performed over a period of time. Essentially, it is an evaluation of how well a process performed.

So the key takeaway is that Cpk is the potential of a process to meet a specification (short term) while Ppk is how the process actually did (long term).

Another way to look at the difference is that Cpk is used for a subgroup of data, while Ppk is used for the whole process. Cpk is typically used while processing in the ideal conditions to identify if the process is capable of meeting the specifications. Ppk tends to be more realistic because it doesn’t cut out real data,  while Cpk data gathering could inadvertently skew the data into looking like a process is capable but not addressing its performance.

When the Cpk calculation is a high number (general industry guideline is 1.66 or higher), then it is a good indication the process is statistically in control. If the Cpk and Ppk calculations are very close or equal, then there is an even better indication that the process is statically in control. However, if the two calculations are considerably different, even though the Cpk value may be acceptable, this is an indication that the process is not in statistical control because there are more data points that have been evaluated in actual process conditions. This is a very important piece of information! Long term, it’s not clear that consistent parts are being produced. Even though they may be within the specification limits, the parts could be at the low or high end of the specification. If a process cannot handle that variation well, this could cause all sorts of issues such as installation challenges, performance issues, and other quality issues, which all cost a lot of time and money.

One thing to note is that many people and even resources will confuse the definitions. You will always want to make sure that the potential versus actual is defined so the same language is spoken between the parties. This will ensure that everyone is on the same page.

References
1. https://www.spcforexcel.com/knowledge/process-capability/cpk-vs-ppk-who-wins#ppk_processes
2. https://www.isixsigma.com/tools-templates/capability-indices-process-capability/process-capability-cp-cpk-and-process-performance-pp-ppk-what-difference/
3. http://www.1factory.com/blog-post-process-capability-basics-cpk-ppk-part-1.html

About Saint-Gobain

Saint-Gobain designs, manufactures and distributes materials and solutions which are key ingredients in the wellbeing of each of us and the future of all. They can be found everywhere in our living places and our daily life: in buildings, transportation, infrastructure and in so many industrial applications.

 

Saint-Gobain Performance Plastics' group of businesses gather solutions to save energy, provide protection, improve comfort and sustain the environment for a variety of markets.

MENU

Capabilities
Materials
Markets
Resources
FAQs
About Us
Contact Us
Schedule a Lunch and Learn
Legal
CATSCA

 

 

 

FOLLOW US

 

 CONTACT US

Saint-Gobain’s medical products are distributed exclusively to medical device manufacturers for use in the manufacture, assembly or distribution of their medical devices. Saint-Gobain cannot authorize the sale of its medical products directly to device user facilities (e.g. hospitals, surgery centers, nursing home, clinics, etc.), nor directly to end users (e.g. patients, patients’ caregiver, prescribing physician, nurse, pharmacist, etc.), including distributors serving device user facilities and end users directly. In accordance with every jurisdiction globally, Saint-Gobain’s customers are responsible for determining that any medical device they manufacture and market that incorporates a Saint-Gobain’s medical product, is compliant with each country-specific medical device regulations and has received proper country-specific clearance, certification or registration authorizing the sale of this medical device.


Saint-Gobain’s medical products offer covers:
- Medical Components [21 CFR 820.3(c)], intended for processing or use in the manufacture or assembly of medical devices before the finished medical device is packaged/labeled; Medical Components are intended to be included as part of the finished, packaged, and labeled device [21CFR820.3(c)].
- Finished Devices [21CFR820.3(l)] made on behalf of medical device manufacturers [21 CFR 807.20(a)(2)] under contract-manufacturing agreement. In accordance with the United States’ jurisdiction, Saint-Gobain complies with the FDA’s requirements for contract manufacturers of finished devices.

© Copyright Saint-Gobain 2019. All rights reserved.