I'm looking for ways to prevent/lessen cmm crash on run

[[Th...]]

Background: The shop I'm working for has a large inventory of many different parts and we cmm many different parts throughout the day. Currently our QC department runs parts on cmm on auto alignment i.e. setup the fixturing and then banked the part and go. Each part has a setup sheet of the fixturing sizes, locations and where to position the part.

Problem is rarely but due to operator error we might place the fixturing a hole off on the Rayco plate and the cmm would crashed.

Do you guys run many different parts a day and how do you try to prevent this kind of crashed from happening?

One idea is switching to manual alignment and take hits to locate part, and if on a production run switch next part to auto alignment if fixturing hasn't been changed. But I'm introducing more steps for the operator to perform which mean more errors will potentially be made.

Does PCM have a function where first part on a production run you are required do a manual alignment. Next part it will ask if fixturing has moved, if yes then you need to do manual alignment, if no then auto alignment?

[[Ch...]]

Yes I would suggest PCM and test some things like diameter size, z height, clocking , etc ...

and stop or back up and have operator correct, etc

[[Cl...]]

We use a Schunk pneumatic pallet system bolted to an R&R fixtures grid plate, located in same the XY center of each CMM.
This never moves. We have a dedicated Poke Yoke fixture for each part we measure, that fits (keyed) into that pneumatic chuck. We perform the start alignment initially for each part program. Once that's been established, we run from the Base Alignment. This eliminates the need for a start alignment each time, because the fixture/part are both in the exact same location every time the program is ran. All our programs are run from autorun. When the program ends, a CNC end park position puts the stylus up and away from the fixture to allow safe removal of the part. There will always be operator error, but the method I described here works very well to eliminate most of those errors.
You run an airline to this with a toggle switch. the piston in the ID locks into the mating part on the fixture base that we make.

[[To...]]

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Do you have to remove the R&R plate when you get your machine calibrated? If so, how does this affect the process?

[[Cl...]]

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Yes, it has to be removed for calibration. After replacing it we just re-run the start alignment.

[[To...]]

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Is it 1 start alignment for all parts or 1 SA for each part?

[[Cl...]]

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I guess you could use the same start alignment off the Schunk, but we use one off each part.

[[DW...]]

Honestly I am surprised Zeiss has not rolled out a camera system that monitors the volume and can compare two images against one another before running a program. When you create the program, you attach a picture of the setup and part and a simple line of code would take another picture on every subsequent run before executing and compare the images. If the images are different, it won't run. Perhaps I should develop this...

[[Cl...]]

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This is where Poke Yoke fixturing comes in handy.

[[Ro...]]

One quick and simple way to make sure the part is in the correct position is to place a CMM Position in your first feature before it runs. Have the probe go over a hole, corner of the part, something so you can just look at it quick and know the part is in the correct location. Have a message pop up to make sure it is located right, clearance plane and off it goes. It is pretty basic, but will only take a second to make sure the part is loaded in the correct location on the fixture.

[[Cl...]]

Thats not a bad idea Robert, but again if you have good Poke Yoke fixturing, were the fixture and is keyed in such a way as to ensure that it can only be installed one way, then the part also can only be installed one way, you've won half the battle.