I am wondering in what business which kind of Cpk standards are used. I know for automotive Cpk >=1.67 Short and Cpk >=1.33 long base is very commen.

Please give me some values used in your business and what kind of products are involved. Thanks!

why are you asking? this will help us frame your request and our answers

Bev D, thanks for your reply. Me is asked to do a benchmark re. this, in order to determine what's a commen standard for our business. We want to follow at least this standard. We produce and sell consumer products for the audio and video market.

The ppk or Cpk or/and Specs normaly are fixed by customers, so if no way to play with them.

There are fields ( aero-space, transport, medical ) that the Cpk must be high because is needed to reduce the risk to produce injures or death, your field looks a "safe" ones, so if the customer doesn't ask for a specific indicator value, 1.33 could be the value.

:2cents:If the customers don't ask for a specific cpk value (fixing the specs and asking for the index value), one thing that you can do is to benchmark other companies to obtain competitive standards for your line of products, or you can evaluate your process and look for better indicators reducing variation and centering on the target of the variables that affect the behabiur and quality of your products. Keep on mind..., if you are just collecting numbers is a useless hobby.

What do you want your Cpk value to be? Unless it is in a guidance document, or standard (government or industry), a Cpk value is just a "snapshot" of your process. The Cpk value you get today will be different than the one you get tomorrow (as more data is added, the standard deviation and mean will change).

Instead of focusing on Cpk, focus on sources of variation. Variation is the enemy of quality.

As Steve has mentioned about variation, variation is the cause of reducing the CPK the wider the spread the lower the CPK, so in terms of focusing on the variation you will be rectifying the CPK, but the correct interval of CPK really depends on the setup(Spec limits) and process(Production type) so most processes will have different results unless they have the exactly the same setup.

Kind Regards,

Omeil