Join

What is Process Capability ? Process Capability Indices | Cp and Cpk

A process capability study is carried out to measure the ability of a process to meet the specifications (Customer Voice).

SPC– Statistical Process Control is used to measure and control the Process Capability and controlling quality during the production process.

The frequency distribution diagram called Histogram and Control Charts are the basic 7 QC Tools that are used to measure, analyze, and control Process Variations and Process Capability.

Process Capability

Process

The process is a set of interrelated activities that convert the inputs such as equipment, materials, people, methods, and environment into desirable output.

The quality of the process is measured by the output of product quality characteristics. If product characteristics/specifications conform to engineering/customer requirements, then the process is considered stable/capable and performing well as per set standards.

A process is considered stable if there are only Common Causes of Variation present in the process.

Process Capability Meaning and Definition

Minimum spread of process variation present in a manufacturing process.

Process capability means how likely a product is going to meet the design specification.

It is the 6 Sigma range of process Inherent variation.

In SPC, Control limits are one of the most basic requirements of a process capability study, So it is very important to ensure the condition of the 4M input while calculating trial control limits.

Process Capability = +/- 3 Sigma = Total spread of 6 Sigma

Need for process capability (PC)

  • For meeting customer requirements/specifications.
  • To measure and control the spread of the process.
  • To provide more realistic tolerances for product dimensions.
  • Improve the process performance capability

Factors influencing PC

  • Condition of machine and equipment.
  • Operation type and operational conditions.
  • Type of Raw Materials.
  • The Skill of Operators and Inspectors.
  • Measurement method.
  • Gauge/Instruments condition.

Tools for PC estimation

  • Histogram.
  • Control charts.
  • Analysis of Variances.
  • Run chart.

Process Capability Indices: Cp and Cpk

Process capability – Cp:  It is defined as the tolerance width divided by the total spread of the process.

process capability analysis

Cp indicates the spread of variation present in a process.

cpk process capability

Cpk Process Capability Index:  Cpk is the capability index that accounts for both the spread and location of the process or the centering of the process.

Cpk in quality is a measure of the process performance capability.

It measures how close your manufacturing process is to the center of the design specification limits.

Cpk in the manufacturing process should be greater or equal to 1.33, and it is defined as the minimum of Cpu and Cpl.

CpCpk
Cp is the Process Capability and it is defined as the tolerance width divided by the process width(6Sigma).Cpk is the Process Capability Index and measures how close your manufacturing process is to the center of the design specification limits.
Cp doesn’t take into account the centering of the process.
Cp accounts for only spread or  variation of the process


Cpk take into accounts for both spread
and centering of the process

Formula:
Cp =  Design Tolerance/6Sigma     
  =  (USL-LSL)/6Sigma

Where
USL- Upper Specification Limit,
LSL-Lower Specification Limit
Sigma(σ) – Short-term Standard Deviation
Formula:
Cpk is the minimum value of Cpu or Cpl

denoted as Cpk = Min (Cpu, Cpl)

Cpu = (USL – X Double Bar)/(3Sigma)
Cpl  = (X Double bar – LSL)/(3Sigma)

Where
Cpu – Upper Capability Index,
Cpl  – Lower Capability Index
Sigma(σ) – Short-term Standard Deviation
Cp should not looked into isolation, it is the only used to find out whether the process is capable or not i.e. Cp  ≥1.33Cpk should always be looked into, it is used to find out whether the process is capable to meet the customer requirements or not i.e. Cpk  ≥1.33

You may also like:

How to Calculate Process Capability? Example and Interpretation

What is Statistical Process Control  (SPC)?

Process Variations | Common Causes Vs Special Causes

126 thoughts on “What is Process Capability ? Process Capability Indices | Cp and Cpk”

  1. I think this internet site has some rattling great information for everyone :D. “Anybody who watches three games of football in a row should be declared brain dead.” by Erma Bombeck.

  2. I have been exploring for a little for any high-quality articles or weblog posts in this sort of space . Exploring in Yahoo I ultimately stumbled upon this website. Studying this info So i am satisfied to convey that I have an incredibly good uncanny feeling I came upon exactly what I needed. I such a lot without a doubt will make certain to do not forget this site and give it a look on a constant basis.

  3. Thank you for sharing superb informations. Your site is so cool. I’m impressed by the details that you’ve on this website. It reveals how nicely you understand this subject. Bookmarked this web page, will come back for extra articles. You, my pal, ROCK! I found simply the info I already searched everywhere and simply couldn’t come across. What a great site.

  4. I’m still learning from you, but I’m trying to achieve my goals. I certainly love reading all that is posted on your website.Keep the stories coming. I loved it!

  5. I like this blog very much, Its a real nice position to read and get info . “Do pleasant things yourself, but unpleasant things through others.” by Baltasar Gracian.

  6. You completed a few good points there. I did a search on the matter and found the majority of people will agree with your blog.

  7. F*ckin’ remarkable things here. I am very glad to peer your article. Thanks so much and i am looking forward to touch you. Will you please drop me a e-mail?

  8. Attractive element of content. I just stumbled upon your web site and in accession capital to claim that I acquire actually enjoyed account your blog posts. Anyway I will be subscribing in your feeds and even I success you access persistently quickly.

  9. Greetings from Ohio! I’m bored at work so I decided to check out your site on my iphone during lunch break. I really like the information you present here and can’t wait to take a look when I get home. I’m amazed at how quick your blog loaded on my cell phone .. I’m not even using WIFI, just 3G .. Anyways, wonderful site!

  10. Hello! Do you know if they make any plugins to assist with SEO? I’m trying to get my blog to rank for some targeted keywords but I’m not seeing very good results. If you know of any please share. Cheers!

  11. I think this is among the most significant information for me. And i am glad reading your article. But wanna remark on some general things, The site style is ideal, the articles is really nice : D. Good job, cheers

  12. I do consider all the ideas you have offered in your post. They’re very convincing and can certainly work. Still, the posts are very quick for beginners. Could you please prolong them a bit from subsequent time? Thank you for the post.

  13. It?¦s actually a great and helpful piece of information. I?¦m happy that you just shared this useful information with us. Please keep us up to date like this. Thank you for sharing.

  14. My brother suggested I might like this blog. He was entirely right. This post truly made my day. You cann’t imagine simply how much time I had spent for this info! Thanks!

  15. Thanks , I have just been looking for information approximately this topic for ages and yours is the best I have found out so far. But, what about the conclusion? Are you sure about the supply?

  16. Very well written information. It will be beneficial to everyone who employess it, including me. Keep doing what you are doing – can’r wait to read more posts.

  17. Greetings from Idaho! I’m bored at work so I decided to check out your site on my iphone during lunch break. I love the information you present here and can’t wait to take a look when I get home. I’m shocked at how fast your blog loaded on my mobile .. I’m not even using WIFI, just 3G .. Anyways, excellent blog!

  18. I precisely wanted to appreciate you once again. I am not sure what I could possibly have tried in the absence of the actual aspects contributed by you regarding my industry. It previously was a frustrating circumstance in my position, however , spending time with your specialised fashion you resolved it took me to jump with contentment. Now i’m thankful for this guidance as well as trust you recognize what an amazing job you’re getting into educating people through the use of a blog. I know that you have never met all of us.

  19. Thanks , I’ve just been searching for information about this topic for ages and yours is the best I have discovered till now. However, what about the conclusion? Are you certain concerning the supply?

  20. When I originally commented I clicked the -Notify me when new comments are added- checkbox and now each time a comment is added I get four emails with the same comment. Is there any way you can remove me from that service? Thanks!

  21. What’s Taking place i’m new to this, I stumbled upon this I have found It absolutely helpful and it has aided me out loads. I’m hoping to give a contribution & assist different customers like its aided me. Great job.

  22. I’ve recently started a blog, the information you offer on this site has helped me tremendously. Thanks for all of your time & work. “Everyone is responsible and no one is to blame.” by Will Schutz.

  23. I enjoy you because of your own efforts on this web site. My mom really loves carrying out internet research and it is simple to grasp why. Almost all know all regarding the lively method you convey functional things via this web site and as well foster response from people on the situation so our own princess is without question studying a lot. Enjoy the remaining portion of the new year. You have been doing a dazzling job.

  24. Thanks for sharing superb informations. Your web site is so cool. I am impressed by the details that you’ve on this web site. It reveals how nicely you understand this subject. Bookmarked this web page, will come back for extra articles. You, my friend, ROCK! I found just the information I already searched everywhere and just could not come across. What an ideal web site.

  25. Nice post. I was checking constantly this weblog and I’m impressed! Very helpful information particularly the remaining phase 🙂 I take care of such information much. I used to be looking for this particular info for a very lengthy time. Thank you and good luck.

  26. I truly appreciate this post. I have been looking everywhere for this! Thank goodness I found it on Bing. You’ve made my day! Thanks again

  27. The very heart of your writing whilst appearing agreeable at first, did not really sit very well with me after some time. Somewhere within the paragraphs you actually managed to make me a believer unfortunately only for a very short while. I still have got a problem with your leaps in assumptions and you might do nicely to help fill in all those breaks. In the event you actually can accomplish that, I could certainly end up being amazed.

  28. I was suggested this blog by my cousin. I am not sure whether this post is written by him as nobody else know such detailed about my trouble. You’re wonderful! Thanks!

  29. I do agree with all of the ideas you’ve presented in your post. They are very convincing and will certainly work. Still, the posts are too short for newbies. Could you please extend them a bit from next time? Thanks for the post.

  30. What’s Going down i am new to this, I stumbled upon this I’ve discovered It positively useful and it has helped me out loads. I am hoping to contribute & help other users like its aided me. Great job.

  31. Wow! This can be one particular of the most useful blogs We have ever arrive across on this subject. Actually Magnificent. I am also a specialist in this topic so I can understand your hard work.

  32. Good write-up, I’m normal visitor of one’s web site, maintain up the excellent operate, and It’s going to be a regular visitor for a lengthy time.

  33. Heya i am for the first time here. I found this board and I find It really useful & it helped me out a lot. I hope to give something back and aid others like you helped me.

  34. What¦s Happening i am new to this, I stumbled upon this I’ve discovered It absolutely helpful and it has aided me out loads. I am hoping to give a contribution & aid different users like its aided me. Great job.

  35. Whats up very nice site!! Man .. Excellent .. Superb .. I’ll bookmark your blog and take the feeds additionally…I’m satisfied to search out numerous helpful information here within the put up, we’d like develop more strategies in this regard, thank you for sharing. . . . . .

  36. It is the best time to make some plans for the future and it’s time to be happy. I have read this post and if I could I wish to suggest you some interesting things or advice. Perhaps you can write next articles referring to this article. I wish to read more things about it!

  37. of course like your web site but you need to take a look at the spelling on quite a few of your posts. Several of them are rife with spelling problems and I to find it very troublesome to tell the truth however I will surely come back again.

  38. Hiya, I am really glad I have found this information. Today bloggers publish only about gossips and web and this is really annoying. A good web site with interesting content, that is what I need. Thanks for keeping this site, I’ll be visiting it. Do you do newsletters? Can’t find it.

  39. Can I just say what a aid to seek out somebody who truly is aware of what theyre speaking about on the internet. You positively know easy methods to convey an issue to light and make it important. More folks have to learn this and perceive this side of the story. I cant imagine youre no more widespread because you positively have the gift.

  40. I am really enjoying the theme/design of your web site. Do you ever run into any browser compatibility problems? A small number of my blog readers have complained about my website not operating correctly in Explorer but looks great in Opera. Do you have any suggestions to help fix this problem?

  41. I must show my gratitude for your kind-heartedness supporting people that actually need help on this important field. Your very own commitment to getting the solution around turned out to be remarkably insightful and have continually empowered women much like me to achieve their targets. Your amazing informative guide implies so much a person like me and especially to my office workers. Thanks a lot; from all of us.

  42. F*ckin’ amazing issues here. I’m very glad to peer your post. Thank you a lot and i’m looking ahead to touch you. Will you kindly drop me a mail?

  43. It is truly a nice and helpful piece of information. I am happy that you simply shared this useful information with us. Please keep us up to date like this. Thank you for sharing.

  44. Thank you for another great article. Where else may anyone get that kind of information in such an ideal manner of writing? I’ve a presentation subsequent week, and I am on the look for such information.

  45. What i do not understood is actually how you’re not really much more well-liked than you may be right now. You are so intelligent. You realize thus significantly relating to this subject, made me personally consider it from numerous varied angles. Its like men and women aren’t fascinated unless it’s one thing to do with Lady gaga! Your own stuffs excellent. Always maintain it up!

  46. certainly like your website but you need to check the spelling on quite a few of your posts. Several of them are rife with spelling problems and I find it very troublesome to inform the reality however I will surely come again again.

  47. I like the helpful information you provide in your articles. I will bookmark your weblog and check again here regularly. I am quite certain I will learn a lot of new stuff right here! Best of luck for the next!

  48. F*ckin’ awesome things here. I’m very glad to see your article. Thanks a lot and i am looking forward to contact you. Will you please drop me a mail?

  49. Thanks for some other magnificent article. The place else could anyone get that type of info in such an ideal way of writing? I have a presentation subsequent week, and I am at the search for such info.

  50. Amazing! This blog looks exactly like my old one! It’s on a completely different topic but it has pretty much the same layout and design. Excellent choice of colors!

  51. excellent issues altogether, you just gained a new reader. What may you suggest in regards to your submit that you just made a few days ago? Any positive?

  52. I¦ve been exploring for a bit for any high quality articles or weblog posts on this sort of house . Exploring in Yahoo I at last stumbled upon this web site. Reading this information So i am glad to show that I’ve an incredibly just right uncanny feeling I discovered exactly what I needed. I so much definitely will make certain to do not fail to remember this site and give it a look regularly.

  53. What i don’t understood is in truth how you are not really a lot more neatly-favored than you might be right now. You’re very intelligent. You realize thus significantly in terms of this matter, made me for my part consider it from numerous varied angles. Its like women and men don’t seem to be interested unless it is one thing to accomplish with Woman gaga! Your own stuffs excellent. Always handle it up!

  54. This blog is definitely rather handy since I’m at the moment creating an internet floral website – although I am only starting out therefore it’s really fairly small, nothing like this site. Can link to a few of the posts here as they are quite. Thanks much. Zoey Olsen

  55. I will immediately seize your rss feed as I can not find your e-mail subscription link or e-newsletter service. Do you have any? Kindly permit me recognize in order that I could subscribe. Thanks.

  56. I love your blog.. very nice colors & theme. Did you create this website yourself? Plz reply back as I’m looking to create my own blog and would like to know wheere u got this from. thanks

  57. Usually I do not read post on blogs, but I would like to say that this write-up very pressured me to try and do so! Your writing style has been surprised me. Thank you, very nice article.

  58. My coder is trying to convince me to move to .net from PHP. I have always disliked the idea because of the expenses. But he’s tryiong none the less. I’ve been using WordPress on a number of websites for about a year and am worried about switching to another platform. I have heard fantastic things about blogengine.net. Is there a way I can import all my wordpress content into it? Any kind of help would be greatly appreciated!

  59. Hey, you used to write wonderful, but the last several posts have been kinda boring… I miss your tremendous writings. Past several posts are just a little out of track! come on!

  60. It?¦s really a nice and helpful piece of info. I?¦m glad that you shared this helpful information with us. Please keep us up to date like this. Thanks for sharing.

  61. I loved as much as you will receive carried out right here. The cartoon is attractive, your authored material stylish. however, you command get bought an shakiness over that you would like be delivering the following. unwell certainly come further in the past again as exactly the similar just about a lot incessantly inside of case you protect this increase.

  62. Hi, i read your blog occasionally and i own a similar one and i was just wondering if you get a lot of spam remarks? If so how do you stop it, any plugin or anything you can advise? I get so much lately it’s driving me crazy so any help is very much appreciated.

  63. I simply wished to say thanks all over again. I do not know what I could possibly have gone through in the absence of the entire smart ideas provided by you regarding this problem. This has been a difficult case for me personally, nevertheless understanding a new skilled way you solved that took me to leap over fulfillment. I am happier for the help and even expect you recognize what a powerful job that you’re undertaking instructing other individuals with the aid of your web blog. More than likely you’ve never got to know all of us.

  64. A powerful share, I just given this onto a colleague who was doing just a little evaluation on this. And he in fact bought me breakfast as a result of I found it for him.. smile. So let me reword that: Thnx for the deal with! But yeah Thnkx for spending the time to debate this, I feel strongly about it and love studying extra on this topic. If doable, as you turn into expertise, would you mind updating your weblog with more particulars? It is extremely useful for me. Massive thumb up for this weblog put up!

Leave a Comment

Your email address will not be published. Required fields are marked *

Social Share Buttons and Icons powered by Ultimatelysocial
Pinterest
Pinterest
fb-share-icon