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Anonymous Poster #1

Rejection PPM Calculation

12/09/2016 10:06 PM

Suppose a manufacturing unit has two departments, let say dept. X and Y,
Processes X1 & X2 are performed at dept. X
& Y1 & Y2 are performed at dept Y.

Now, suppose 10000 nos. of pieces gets processed during X1 process...10 pieces gets rejected...so its output is 9990 good pieces....
so only 9990 nos of pieces gets processed during X2 process...& 30 pieces gets rejected during X2 process...so the output is 9960 nos of pieces...
So only 9960 nos of pieces is carried forward for further processes at department Y.
Where again 50 pieces gets rejected at dept. Y i.e.during Y1 & Y2 processing. So ultimately 9910 nos is the good production.

Now the question is how to calculate Rejection PPM for process X1, process X2 & for department X.? How to calculate rejection PPM of Plant?

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#1

Re: Rejection PPM Calculation

12/09/2016 10:21 PM

By simple arithmetic.

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#2

Re: Rejection PPM Calculation

12/09/2016 10:21 PM

Sounds like a homework problem.

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#3

Re: Rejection PPM Calculation

12/09/2016 11:08 PM

You have a good point here. How does one calculate PPM when one does not understand what the three letters "PPM" stand for: Pi$$ Poor Management; Pecans, Pralines and Macaroons; Peter, Paul and Mary (that's before your time)

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#18
In reply to #3

Re: Rejection PPM Calculation

12/11/2016 10:46 PM

If I had a hammer . . . .

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#4

Re: Rejection PPM Calculation

12/09/2016 11:41 PM

In each instance, 1,000,000 (nin - nout)/nin.

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#5

Re: Rejection PPM Calculation

12/10/2016 10:24 AM

It's not how many get rejected, it's how many get returned that matters....

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#6

Re: Rejection PPM Calculation

12/10/2016 10:59 AM

I prefer to analyze DPMO, and not PPM as PPM does not give any indication as to why the parts got rejected.

Maybe you could shoot up a flare, cause you're lost!

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#7

Re: Rejection PPM Calculation

12/10/2016 11:04 AM

Create a new department called A1 and have them count all the rejected parts.

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#8

Re: Rejection PPM Calculation

12/10/2016 11:40 AM

You asked: "How to calculate rejection PPM of Plant?"

The aggregate rejection rate, ie, of all the departments combined, ie, 'the plant', in the same manner as Tornado outlined above in #4.

-----

ps: If this is a homework problem (and a trivial one at that), I'm guessing you:

* aren't paying attention in class?

or

* are paying attention in class but have no knack for this sort of thing and so may wish to reconsider your major?

I'm not trying to be snarky. Really I'm not. I'm just thinking that if you've honestly tried to understand this stuff but just can't get a feel for it, you may wish to consider an alternative major; something more suited to your particular talents and abilities. No crime in that - the best software engineer I ever met bar none was a medical-school dropout. His dad wanted him to become a neurosurgeon but his true love was computer science. He eventually got his PhD in that.

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#9
In reply to #8

Re: Rejection PPM Calculation

12/10/2016 11:48 AM

I'm betting we'll never hear from this joker again.

Another reason to ban anonymous posters. No way to track the lazy losers and differentiate them from real members.

If even anonymous posters have to register, as I have been told, let them stand behind all their posts!

I don't buy Phys argument. If you're afraid of losing your job over something posted on an anonymous forum. don't post it!

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#10
In reply to #9

Re: Rejection PPM Calculation

12/10/2016 12:18 PM

I don't have an opinion either way on anonymous posters and so can't speak to that; perhaps the OP here is simply too embarrassed to associate his/her name with the question. I dunno, but behind the anonymity is a real person - possibly a student - struggling with what for many here I'm sure is a fairly trivial concept. Obviously some posters feel anonymity is necessary, so why do they? Some are trolls, to be sure. But for those who are not, maybe we are supplying the motive? Perhaps if we were not so quick to castigate posters they would have much less reason to wish to post anonymously?

I have no idea who this person is, much less that they're a 'joker' or a 'loser.' Nothing this poster has said suggests anything of the sort, at least not to me; and aren't people generally much less likely to preemptively hide behind a defense when they're not expecting to be shot at? With all due respect, Lyn, maybe we are the problem. If we are, the question now becomes: what do we do about it?

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#11
In reply to #10

Re: Rejection PPM Calculation

12/10/2016 1:10 PM

No, "we" are not the problem here. There are clear prohibitions on asking homework questions here.

Surely, the student(assuming that is the case) is aware of the internet, and I'd bet $5.00 that they used a search engine to find CR4.

I'd also bet that by asking that question, the "person" would have heard the term 6 Sigma, as it is the source of the PPM/DPMO terminology relating to defective parts, or actually operations.

Following that, is it unreasonable to assume that that same person would have the gumption carry the process forward and simply type 6 simga into that same engine and come up with 430,000 different explanations of how it works and how to figure the defect rate.

No, "we" are not the problem here.

The problem is that many people had rather have someone else do the research for them and simply provide them with the answer to the question while remaining clueless about the hows and whys of the answer.

You have not been a member long enough to see that many times the forum gives more than enough help to honest people who explain their reasons for asking, students included.

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#12
In reply to #11

Re: Rejection PPM Calculation

12/10/2016 1:28 PM

"Another reason to ban anonymous posters. No way to track the lazy losers and differentiate them from real members.

"If even anonymous posters have to register, as I have been told, let them stand behind all their posts!"

My reply was in the context of your stated objections to anonymous posters, not posters posing homework questions, was it not? If you are equating 'lazy losers' with those posting homework questions, perhaps you should have made this equivalence clear? I am not a telepath, Lyn, in spite of my ex's insistence otherwise.

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#13
In reply to #12

Re: Rejection PPM Calculation

12/10/2016 2:29 PM

What we have, is failure to communicate.

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#14
In reply to #13

Re: Rejection PPM Calculation

12/10/2016 4:36 PM

Well, I suppose we could say that there is a failure to communicate. Superficially it may look that way, anyway, but I think we both know that isn't the whole story.

I rather think I touched a nerve when I alluded to the fact that the behavior on this forum may prompt others to use anonymity as a preemptive defense. Would you agree that civil behavior on this forum is somewhat lacking? I mean, I've only been here a few days and even I can tell.

Not once in your post did you say anything at all about homework posts. Not once. The entire thrust of your post concerned anonymous posters generally. But in reply to my comment you suddenly switch horses mid-stream and now the context is homework questions specifically? Why would you do that when the context of my comment was perfectly clear - unless of course the subject is hitting a wee bit too close and so we bring out the diversionary tactics? Dead giveaway. So why are you so uncomfortable with the idea that we may be largely at fault where anonymous posters are concerned? Because it's true?

There was no failure to communicate, Lyn. We understand each other perfectly.

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#15
In reply to #14

Re: Rejection PPM Calculation

12/10/2016 5:25 PM

Sensitive PC answers has went....

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#16
In reply to #14

Re: Rejection PPM Calculation

12/10/2016 7:16 PM

"I've only been here a few days" says it all.

Instead of offering lessons in forum etiquette, you can always do everything in your power to answer the question offered by the Anonymous Poster.

Aside from suggesting that they change professions, what have you offered in the way of constructive help, except:

"you may wish to consider an alternative major"

" If this is a homework problem (and a trivial one at that), I'm guessing you:

* aren't paying attention in class?"

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#17

Re: Rejection PPM Calculation

12/11/2016 9:22 AM

I'm guessing that if you knew that 1% is equal to 10,000 ppm, you'd be able to answer this question yourself.

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#19

Re: Rejection PPM Calculation

12/12/2016 8:01 AM

Those sorts of rejection figures just wouldn't be acceptable in a Japanese manufacturing unit; these just don't make rejects.

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#20

Re: Rejection PPM Calculation

12/12/2016 2:57 PM

I'm at home and can do some work on this. Homework you might say. I think I have read and answered your question correctly. No doubt soon to be advised by CR4 members if not. This is how I see it.

X1 has 10 rejects out of 10,000 they started with. Pro-rate this means they would make 10 dud ones for every 10,000 they take in, until they made a million, where there would be one thousand rejects. The same as saying 1,000 ppm in numbers.

X2 has 30 rejects out of 9,990 they started with. Pro-rate this means they would make 30 dud ones for every 9,990 they take in, until they made a million, where there would be 3 thousand and 3 rejects. The same as saying 3,003 ppm in numbers.

Y1 has 50 rejects out of 9,960 they started with. Pro-rate this means they would make 50 dud ones for every 9,910 they take in, until they made a million, where there would be 5 thousand and 20 rejects. The same as saying 5,020 ppm in numbers.

Finally (although not asked) the overall rate would 90 rejects in all from the original 10,000 which is 9,000 ppm.

I don't have any experience in mass production or sampling methods, but it sounds quite a lot to me.

Mathwise words: Quantity of Rejects times 1 million divided by quantity to start with = qty in ppm

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