consistant sizes moving citizen m32

Peeps,
Ive had a Citizen Cincom M32 for about 2 months now, set up to produce a pretty intricate part roughly 120mm long. Proved job, got 1st off, been running since.
However, when inspecting I've noticed the sizes have been jumping.
Long story short, looking properly the machine will run a perfect part, next part is 0.07 big head one, 0.04 big head 2 on ALL dimensions.
Next part perfect, next part big, next part perfect, next part big...
The big parts are consistently big to within .005mm. Its almost like the machine has a parameter to move after each part.
Any ideas guys?

T13

I would check the tool holder. Those tun tool insert pockets do wear and the insert can rock back and forth.

Its too consistent for wear on the tooling, also there are 3 different tools finishing the diameters and all the sizes over the different cutters are moving constantly. Citizen have themselves said it's probably a programming error but I have no communications set up to the machine to send them a copy for review.

Are you canceling offsets after each cut with a T00 and a move? Old Fanucs had issues if you didn't do that, worth a try.

Perhaps you have a bent "cam pin" in your stick tool. That will cause a headache.

Strange problem to chase down. If it is that repeatable, perhaps you can 'trick' the control by running a second copy of the program at a different work offset. Initially, just make both work offsets identical, but this would have the effect of forcing the control to at least reread the work offset. Then, if the problem continues, make an adjustment in the second work offset to bring it into wack.

if you are using tnrc make sure you do not activate it and then have two lines of information in a row without axis motion until it is canceled, this can cause what you are seeing

Possible sticking guide bushing?

Maybe it has a little slop?

Doo you ever pull the bar back inside at all?

I'm just wondering - if a draw-back movement could pull the bushing back into the taper a little more (tightening it up), and then sometimes it stays there, and sometimes maybe it slips out (looser) a little bit - allowing a larger diameter.


With 3 diff tools and all acting the same - I'm going with mechanical somehow, and the "spindle (bushing)" is about the only common denominator that I can think of.


Are all tools on the same X axis?
Could be a loose belt, pulley, keyway, or sleeve connector?


----------------------------

Think Snow Eh!
Ox

turner13 said:

Peeps,
Ive had a Citizen Cincom M32 for about 2 months now, set up to produce a pretty intricate part roughly 120mm long. Proved job, got 1st off, been running since.
However, when inspecting I've noticed the sizes have been jumping.
Long story short, looking properly the machine will run a perfect part, next part is 0.07 big head one, 0.04 big head 2 on ALL dimensions.
Next part perfect, next part big, next part perfect, next part big...
The big parts are consistently big to within .005mm. Its almost like the machine has a parameter to move after each part.
Any ideas guys?

T13

Click to expand...

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often it is a machine warming up and changing size thing. a warmup or long G4 delay sometimes used
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others is slides can have backlash and rocking motion on direction reversal. like 4 legged chair with one leg short it can tilt when a axis reverses direction. i often use programs with programmed moves to always come from same direction to lower backlash problems. so restarting it will use extra moves just in case so again always coming from same direction even on restart
.
i have also seen where coolant temperature caused tooling to change size during long cuts. for example a final cut being bigger or smaller than a test cut. even with coolant temperature control a coolant spray through evaporation creates a cooling effect from the evaporation

I'm with Ox...mic your material and see if it varies and also double check to make sure the guide bushing is adjusted properly.

Eeeeeh, I take that back...I doubt it's material if your parts are bouncing back and forth that consistently.

You’re saying a part will be oversized on dimensions turned on both the main and sub spindles?

That machine has thermal compensation, which axes is it active for? Try running with it turned off for a day.

i have seen hundreds of times where a bigger boring head made of aluminum and steel is getting smaller as its cutting
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basically measure test cut say 10.0000 and final bore starts as 10.0000 and back of bore is 9.9995 cause of cooling action of coolant. same boring bar used hours later with no adjustment will do same thing start a bore at 10.0000 and back of bore 9.9995 so its not cutting edge wear.
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i have also seen where tool and tool holder was getting longer and lower on a vertical mill as much as .0008" lower from end of cut compared to beginning. again recutting often it will do same but maybe only .0004 lower at end cause beginning of cut tool holder still warm. sometimes just use a 5 minute G4 delay with spindle running to give it time to warm up.
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turning coolant on and off can easily cause temperature changes. thats the whole point to prevent overheating but the "cold" coolant even evaporation from coolant spray can be hard to get perfect temp control over