# PPM - Determining Parts Per Million to measure our incoming goods rejections

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#### Raam

We would like to measure our incoming goods rejections in parts per million. Can anyone tell me from where can I get more details on this.

Thanks

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#### Jim Biz

I would think if you have the data - one could input the figures into any number of stastical programs..

The program I am most famillar with is "PCCTK"
(Process Control Chart Tool Kit) but there are many others available.

I did a SEARCH of this site that you can duplicate using PPM as a key word and found 17 threads dealing with PPM issues (all in the Statistical Techniques & 6 Sigma section.

Hope this helps

E

#### energy

Try this!

Raam,

I've had this formula for awhile. If there is anything wrong with it, you can be sure that some of the regulars will attack it with vigor!

If you have a "lot" of 100 parts and you have 6 rejects, divide 1,000,000 by 100 (10,000) then mutilply 10,000 by 6......answer is 60,000 DPPM (Defective parts per million) or a 94% accept rate or a 6% reject rate

OKAY Boys, bring it on!

A

#### Al Dyer

Energy,

Hats off, you remember your basic algebra!

M

#### M Greenaway

Well done energy.

I was going to reply to this one but thought the answer too obvious.

Basically a calculation of parts per million is the same as a calculation of percent (or parts per hundred).

Take the quantity defective, divide it by the quantity produced and then multiply by a million.

No sweat.

A

#### Al Dyer

Raam wrote"

"We would like to measure our incoming goods rejections in parts per million."

I read that to mean he wants to record rejected incoming goods in the PPM format.

Atul, while your formula is very correct for "hypothetical" PPM's it is different than actual PPM. PPM needs to be based on quantity as well as quality. If my SQA called me to his/her office because I had a PPM of 1000 for the year based on sampling, I would ask for the hypothetical parts so I could verify them on my hypothetical CMM.

Maybe I'm too attuned to automotive methods in thinking that PPM's are just a different method of reporting actual scrap or rejects.

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Rejected parts X 1,000,000 / total parts = PPM
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D

#### Dawn

When we reveive 2000 parts returnd from the customer; my formula is in Excel and I just plug the numbers every month:

Formula= Total pieces scrap/Total pieces shipped X 1000000
This is added to a yearly chart with a goal. Any comments?

A

#### Al Dyer

Sounds good Dawn, algebra works.

M

#### M Greenaway

Wow

I havent come across measuring PPM based on sampling inspection before - I wonder how reliable the figure is ? I guess it is only a probable PPM.

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#### Sam

Dawn, Thats exactly how DC figures PPM as part of their rating system.