Mazak QT350 Nexus Program Shift Losing Position??

[Arc-On]

So, I have a 2002 Mazak Quick Turn 350 with the 640T Nexus control.

I'm having problems with the machine shifting the program with repetitive parts.

I'm making a simple part in delrin, its basically a fancy cap that goes over a seal. 3.25" diameter bar, the part basically looks like a large bottle cap. Real simple stuff, turn to diameter, drill, bore, put a groove in the OD, part off. I don't have a bar feeder/puller so in the past what I'd do is pull out maybe 8" of bar, and just have Mazatrol shift the program over 4 or 5 times and repeat while I go do something else, then I just manually pull out more bar and keep it going.

Today though it isn't shifting properly. Program is set up to repeat 5 times, each time shifting zero 1.405". The first part comes out fine, the second part comes out fine but the third part crashes. The tool we use for facing and turning seems to lose track of where it is in space and hits both the face and the OD in between the rough and finish passes.

It's weird, the tools all seem to be hesitant or "confused" for lack of a better word after the first part. On part one, all the tools go right to where they need to go for the start of the cut. On part two, the tools go to a point close to but seemingly unrelated to part geometry, pause a second, then go to the shifted start point. On part two, they don't crash or hit anywhere they're not supposed to be, but on part 3 the tool just seems to ignore the just cut part geometry and drives the tool right to where the start point is of the next op and hits the part in the process.

Any thoughts?

 

[Arc-On]

Part is supposed to be like on the right, the left part is what happens on part 3 of the cycle. I stopped it before it tried to drill and bore.



I tried again from the beginning and it did the exact same thing. I figured I might have an issue with my program somehow so I redid the program on a new number but it didn’t change anything.

I can’t find what’s causing this. Part one is bang on to the numbers, part two is also correct but the tools act funny after one shift and after two shifts it all goes to shit.

But the machine seems to still cut accurately if I start back over at one, it’s like it loses something somewhere after shifting zero a few times?

 

[Philabuster]

Sounds like the stock is moving in the jaws during the machining op? It's plastic, so you cannot chuck on it very hard. I have never seen the end process loop have an issue repeating or holding size with old or new controls, but I don't know.

 

[gmc1724]

Part is supposed to be like on the right, the left part is what happens on part 3 of the cycle. I stopped it before it tried to drill and bore.

View attachment 392768

I tried again from the beginning and it did the exact same thing. I figured I might have an issue with my program somehow so I redid the program on a new number but it didn’t change anything.

I can’t find what’s causing this. Part one is bang on to the numbers, part two is also correct but the tools act funny after one shift and after two shifts it all goes to shit.

But the machine seems to still cut accurately if I start back over at one, it’s like it loses something somewhere after shifting zero a few times?

How much memory do you have left? I've seen weird things happen when the memory gets towards full, try removing some programs and see if helps.

 

[Arc-On]

Sounds like the stock is moving in the jaws during the machining op? It's plastic, so you cannot chuck on it very hard. I have never seen the end process loop have an issue repeating or holding size with old or new controls, but I don't know.

I do mostly plastic, we have a decent handle on our work holding, but I can adjust the chuck pressure and see if anything changes.

I’m using hard, serrated master jaws, normally that stuff grips delrin and doesn’t let go.

Problem is I can watch it try to do the wrong thing. Like, it does the rough op of the bar out then tries to drive right into the bar headed for the start of the finish pass. Taking maybe .05” on the rough pass. You’d think it would move on the first or second part of the stock was moving.

I’ll try dropping the chuck pressure down a bit and see if that changes anything.

 

[Arc-On]

How much memory do you have left? I've seen weird things happen when the memory gets towards full, try removing some programs and see if helps.

I think I have maybe 20% of the total machine memory used, but i do have a lot of programs in the active directory, that directory is pretty full. I’ll try moving most of them to the backup directory and see if that changes anything. Thanks.