Mazak Help I scrapped a part and I don't understand exactly why.

[Andre.Savoie]

Hello,

Like the Title says I have a problem, I don't know what seaquence of events caused me to scrap a part I was working on.

The program was proven, I had done 2 parts previously. My roughing tool was a 332 VNMG od tool, the lathe I was working on was a Mazak PowerMaster Universal with a 12.5" spindle Bore. The controller is a Mazatrol Fusion 640.

This is the scenario I am faced with, I had proven the program and done 2 parts, I was machining Chrome 13, I was running the program in Single Process, Process one was a Copy In operation roughing the Pre-Roughed OD. The insert broke ( not the main problem). What I did next caused the problem that scrapped the part.

This is the part I am unsure of, I turned the mode to handle and backed out the tool a bit (I cant remember if I was in handle or zero returned and didn't finish the stroke) I replaced the insert and I can't remember if I reset the program or not I don't believe I did, then I hit automatic mode again and went directly to Single Process and selected the Copy In process that I was just using, the tool started cutting but it started cutting .180 deeper then was programmed this is what is stumping my I don't know what I did to screw that up, I didn't change the program or the tool offsets of geometry.

The insert broke again because it was taking too deep a cut this is when I realized something was wrong. I rest the program put a .060 positive X axis offset in and zeroed the machine on X then Z, then proceeded to start the Copy In via the Single Process again, this time it cut fine and the diameters were on size but I only realized this because there was a huge step in the part diameter when there shouldn't have been this was a .186" step I can account for .06 for the X offset change but I was stumped I checked the tool geometry by going to manual and taking a test cut on the OD by hand and measuring the OD with a Micrometer the Positions display showed that the tool was accurately displaying the diameter it had cut.

I am stumped please some one give me some advice on what I did wrong to cause such a huge jump in X diameter (.120") I don't want to repeat this mistake.

Thank you for your time and input,

Sincerely,
Andre Savoie

[jimiscnc]

One remote possibility is the MANUAL ABSOLUTE is off. This seldom used capability means that the machine does not know it's been moved, if done manually.

Another even slimmer possibility is that the machine was not reset, and it was still trying to run the program that had previously been running?

Don't think I've offered anything constructive, here. Just trying to get the ball rolling.


-jim

[Andre.Savoie]

I actually tried to get it to cut deeper again on the bad piece, I went into manual and moved +X a few .100 of an inch and didn't Reset then went back to Single Process and ran it again, the lathe was out but it was out +X not -X like what happened earlier to me.

I will look into the Manual Absolute off but I believe it is turned on, where and how would I verify this? (When I move in on Manual the tool displays the true X diameter as measured with a micrometer, it does not add the offsets table when in manual mode, does this tell me anything?) Ie. if I have a .06 offset on X for tool 3 and I touch it to a 3.500" diameter it displays 3.500" in Position screen on X axis, should it display 3.440" or 3.560"?

I do appreciate the input Jim thank you for contributing. I find it helps to come up with different verbatim and good trouble shooting.

[Andre.Savoie]

does anyone have anything to add to this? I am going to test a few things, like moving away from the work piece with zero return but not actually returning to zero stopping after a quick rapid on X+ to see if it adjusts X- in anyway. I don't believe the machine has Manual Absolute or Absolute encoders turned on because I have to zero the lathe each time I start it up. If it had Manual Absolute I would not need to start the lathe before going into automatic mode. I see lots of people have viewed this thread but I hope more people reply. The weird thing is I didn't go back in on the X axis so Im stumped as to why it made the diameter so much smaller. if anything it should have just cut air.

[Andre.Savoie]

UPDATE:

I tried to replicate the results and manual absolute is definitely not turned on, But as I suspected when I wheeled out on X axis by hand the only thing it did was keep cutting but at the X level I was at i.e. a larger diameter, so im still stumped but im going to try to do a program restart and then go at it again with the hand wheel.