MMC Result

[[Ke...]]

I recall the topic being discussed, but I can never find the old topics in the forum history...

Q1: how do I quantify the last result "Position (M)" (I thought it was said that it was a percentage of some sort), and how is it calculated?

Q2: If I am doing a Best Fit position in the X direction, and I it displays Y also... how do I remove the Y direction evaluation form the report? (Can this be done with the basic version of PiWeb

[[Er...]]

Maybe this link will help some. Not sure about your second questions though.

viewtopic.php?p=26152&hilit=removing+M#p26152

[[Ke...]]

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Thank you sir, that is the topic I was thinking of!

[[Jo...]]

You can turn off "additional" reporting and use result elements with formula to select Datum shift values.

shift.JPG

[[Ri...]]

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Regarding Q1: It is a percentage, but it is also factored.

So say your base tolerance is 0.1mm, and for the sake of simplicity your bonus tolerance is 0.025mm, so your total tolerance is now 0.125mm. If your actual was 0.071mm that would mean you used 56.8% (actual divided by total tolerance).

So technically Calypso/PiWeb should show 0.568 as your result with a tolerance (on the .M) as 1.0, but it doesn't, it likes to show that, it likes to show the base tolerance, so you will need to factor. In this case my base tolerance was 0.1mm, so 0.1 is a factor of 10 to 1.0, so just take your 0.568 and divide it by 10, and you will get 0.0568 for the .M



So if your case, it looks like your base tolerance is 3mm. Your bonus tolerance was 0.1505mm for a total tolerance of 3.1505mm. Your .M SHOULD be 2.7629/3.1505 to equal 87.697% or 0.87697, but once again calypso doesn't like showing that, so you will need to factor it. 3mm is a factor of 3 times 1.0, so take your 0.87697 times 3 and your result should be 2.6309.


I'm not a huge fan of the factoring because it's just confusing, but it is what it is.

[[Ke...]]

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Wow. Thanks. I *never* would have figured that out 🤣

[[Ri...]]

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Well, just wait until you use a base tolerance of 0 and see what happens.

Hint - it doesn't work because since it is trying to factor, it will always be 0.

[[Je...]]

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In much simpler terms .m = (Actual / (Tolerance + Bonus Applied)) * Actual

This is almost purely for statistical purposes as floating tolerance values throw SPC on its ear.

[[Ke...]]

The reported actual of the ".M" value is the equivalent calculated actual as if there were not bonus tolerance.
In this example, we have with bonus tolerance: (2.7629/3.1505)=87.7% of total tolerance used.
And without bonus tolerance: (2.6309/3.0)=87.7% of total tolerance used.
This is useful because statistical calculations do not like variable tolerance, so this gives a way to have a consistent tolerance for those calculations.
The formula for calculation your ".m" value would be: ".m" = (measured actual / (tolerance + bonus applied)) * tolerance
In this example: (2.7629/(3.000+0.1505))*3.0=2.6309

PiwebTPDotM.png

[[Ri...]]

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Jeffrey,

That math doesn't work.

Please look at my example.

.M = (Actual / (Base Tolerance + Bonus Tolerance)) * (Base Tolerance)

I understand the need for SPC, but the factoring is absolutely unnecessary, and in the case of 0 base tolerances, it breaks the calculation.

It would just be much simpler if it was .M = (Actual / (Base Tolerance + Bonus Tolerance)). Then the upper limit of the .M should always be 1.0 or 100%

[[Ri...]]

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Sorry I skipped over your reply.

Yes, I agree with the math, but I don't agree in the last portion of the calculation. Which is why I said it completely breaks when you have a base tolerance of 0.

There should be no need of conversion/factoring. It should always just be a percentage based on 100% or 1.0 being the upper limit.

[[Je...]]

My mistake. Didn't proof-read. Should have copied from my notes instead of retyping.

.M = (Actual / (Tolerance + Bonus Applied)) * Tolerance.

Kevin is correct.

[[Gu...]]

Challenge at MMC
Characteristics that have MMC are assigned an additional characteristic in the database to make this characteristic statistically capable. The challenge with MMC is, that tolerance can change with each measurement. In the database, the tolerance for a characteristic is available only once, in contrast to the actual value, which is available multiple times in the system. If the tolerance changes due to MMC/LMC bonus, it will be overwritten. Thus, no statistical statement can be made about this characteristic.

Summary:
Characteristics that have MMC are not statistically evaluable, since the tolerance can change with each measurement.
The scaled additional characteristics for MMC can be statistically evaluated. With the scaled additional characteristics, however, you still have the problem that the MMC bonus can have different effects on the situation.
For uniqueness, it is recommended to statistically evaluate the inspection characteristic without MMC.

[[To...]]

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Will this (M) become a user-selectable option for non-SPC users?

[[Gu...]]

Activate/deactivate MMC output in the report. Will that be possible?
The scaled MMC value must always be output in the CALYPSO standard reports, regardless of whether statistics are used or not.

Reason:
The possible change in tolerance caused by MMC/LMC is the tolerance value that is in the database. If you would now select an older measurement with the StandardProtocol.ptx, then the last tolerance calculated by MMC/LMC applies as the reference for the deviation. This is basically the same problem as with a statistical evaluation. The scaled measured value, on the other hand, retains its tolerance and is therefore not changed. If you didn't see the scaled reading, you wouldn't see the potential problem.

When exporting results to other statistics programs, please note:
The possible tolerance change in MMC/LMC is a fundamental issue in every database. Our PiWeb enterprise has a "tolerance history" function. If necessary, this would generate new database records for each measurement. However, the bonus extension by MMC/LMC with each measurement is not a tolerance history.
If you generate your own reports, you can connect an individual selection of characteristics. If you don't select the scaled MMC/LMC, you might not see the problem described.

By the way:
With CALYPSO 2023 we are bringing a new basic function. You can automatically save pdf files that were generated with Reporting to the data record of the measurement. We are thus expanding the data set to a “pdf measurement report database”

[[To...]]

The number 2 question I get from customers is "What is the (M)? on my report?"

The number 3 question is "How do I take if off my report?"

[[Ca...]]

Richard,

You can always make a suggestion to have that changed to be between 1 and 0 on the MyVoice section of the ZEISS Portal. https://portal.zeiss.com/my-voice/software/metrology

It looks like this topic was covered extensively here, but I also wanted to add to this post a few articles from the Knowledge Base so that anyone who comes across this thread in the future can have all the information we have gathered for this as well:

Here is an explanation on what the (M) is: https://portal.zeiss.com/knowledge-base?id=401667

And here is an explanation on how to hide the .(M) if you do not want it on the report: https://portal.zeiss.com/knowledge-base?id=458620