Ppk - Seeking short-term study examples - Chronically unstable processes

[Joe_winter]

As no R&D, ppap is necessary in our inc.But where chronically unstable processes in ppap manual I.2.2.9.2? We just offer cpk over time and never ppk for short-term studies, and I can not find one example. Pls help me!

[Al Dyer]

Welcome!


What exactly are you looking for in an example?
Al...

[Joe_winter]

Yeah!!! Here I am freshman. one week ago, a new customer came touring, he asked for ppk studies for his future product, and I am the QC responsible for it, confused by ppk requirement. c/p pk value, ofcourse, they are facilitated. btw,the product is clocked-timer,to UL917.
Joe

[Wes Bucey]

Originally Posted by Joe_winter

Yeah!!! Here I am freshman. one week ago, a new customer came touring, he asked for ppk studies for his future product, and I am the QC responsible for it, confused by ppk requirement. c/p pk value, ofcourse, they are facilitated. btw,the product is clocked-timer, to UL917.
Joe

Welcome to the Cove, Joe

In order for us to help you, we need a little more detail about your situation.
It's still the weekend in Europe and America, where most of our Covers work, so you may not get answers for almost 24 hours from the time I write this post.

Please tell us

• more about the product you make (clocked-timer, to UL917)
• if it is custom made to the customer's specifications
• if it is a product designed by your organization and sold to more than one customer
• the quantity per hour or shift or day
• whether the customer has outlined "critical characteristics" for his product
• whether there are critical characteristics your own organization has identified which will affect fit or function of the product
• if there are "process critical" characteristics which can be noted during production which will indicate whether there may be a problem with the finished product (for in-process inspection purposes)

I note in another thread you talk about a "family of parts" - are you talking about that same "family of parts" in this thread? Tell us what differentiates one member of the family from another (size? color? etc.?)

UL 917

STANDARD FOR SAFETY FOR CLOCK-OPERATED SWITCHES
Scope
These requirements cover clock-operated switches rated 600 V or less, to be used in ordinary locations designed to close and open circuits to a load at predetermined intervals, and intended to be employed in accordance with the National Electrical Code, ANSI/NFPA 70.

These requirements cover only clock-operated switches in which the switching contacts are actuated by a clock-work, by a gear-train, by hand, by electrically-wound spring motors, by electric clock-type motors, or by equivalent arrangements. In addition to closing and opening the switching contacts, the devices may also indicate the time of day or time interval.

These requirements do not cover devices incorporating electronic timing circuits or switching circuits without separable contacts.

A clock-operated switch, which is incomplete in construction features or restricted in performance capabilities, is acceptable for use as a factory-installed component provided that the restrictions established for the component are eliminated when the component is installed.

Specific provisions are included in these requirements for TV rated clock-operated switches. A product that contains features, characteristics, components, materials, or systems new or different from those in use when the Standard was developed, and that involves a risk of fire, electric shock, or injury to persons, shall be evaluated using the appropriate additional component and end-product requirements as determined necessary to maintain the level of safety for the user of the product as originally anticipated by the intent of this Standard.

[Joe_winter]

Thanks, Wes!
about the product :
1-being a new one, never done before.
2-run is also via spring motor, components plastic, e.g. small gears, and hardwares, e.g. springs, axes, materials include AL,plastic,stainless steel,etc.
the processes include injection, punching, assembling.
3-I just feel confused about where ppk for short-term is, an example is hoped to ****.
4-As new product, how to know whether stable ro not??no historics data would be utilized? just by the other similar procucts, or just rule of thumb?

I am in a plight.Shed some light!!

[Howard Atkins]

If I understand the customer wants a PPK study to see the capabability for a new process.
This is standard and the PPAP manual gives the alternatives depending on the stage of production.
In the initila stage if you have only run some 300 parts then the PPK is what you need.
In general there is a looseness of speech in this area and people say CPK instead of PPK and the opposite.
In fact the PPK gives you some important information as to where you are at the beginnig.
I hope this helps.

[remsqa]

Hai Joe

God to see in another thread,The ppk is done for the Charactertics in which the same required control and the same should be measurable.

The short and long time are the confusing part of Quality world don't got in to that.

Ex Short term: IF the customer requirement is 1.67 ppk & CPK. Is your process is getting only 1.33 then your short term willbe achive immediately 1.67 .

Ex Long term : IF your co is a sixsigma Co then you should get 2.00cpk to operate in 50% of tolerance Then your long term is to get the process to perform the cpk more than 2.00 .

Expecting all your mails.and feedback.


REGARDS

R.L.SATTHISH KUMAR

[Joe_winter]

Thanks remsqa as well as Howard!

Howard, your 'looseness of speech' greatly illumines me. sometimes, there are actually difficults to separate where ppk or cpk, as routine processes cpk are adequate, otherwise ppk will get more risks to be attained although it would provide your more informations important.
Don't got in long/short term? that is good idea,but I would have to face requirements from my customers. and my co. is not 6sigma without R&D, that is a small one, the usual reqest is cpk, except the recent ppk from a new customer.