Dimensional ptoblem

[Alex S.A]

HI Guys!
I need your help again. I am facing a problem one gantry equipment.
The problem is on dimensional on cutting part with oxyfuel process.
I checked some things out, as:
1. The kerf used;
2. The parameters of process for 1/2" thickness;
3. I used a pen to measure the dimensional then I found I little bit difference on transverse axy (Y) after that I corrected the parameter of encoder and the difference was ok;
I observed that the problem happens in kind of program only another ones are okay. this problem happens in a bigger part(3688X866 mm), in smaller parts the problem does not happen
I used Axor servomotors and the CNC is Vision Le from ESAB.
I am not sure if the problem is in encoder so that I would to receive some guindance from you to get a soluion for problem.

I am looking forward to hear back from you soon.

Thanks,
Alex S.A

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[Al_The_Man]

Usually that problem is you do not have the right encoder multiplier, you say you have changed the parameter, but if it is off, it will show up on the larger part.
Did you use a known method for measuring and correcting.
I use this formula.
X/Y = Z
1/Z * W = New Value
Where X = The distance the Machine readout shows.
Y = The distance the Machine actually travelled, measured with as much precision as possible over long distance.
W = The Value that is in the machine Parameter.
It normally takes a couple of tries to zero in on the correct number.
Al.

[Alex S.A]

Hi Al the Man,

As regards you wrote I made this procedure and checked it by make the trace using a pen and the result was okay. As you wrote I had to do the calculating many times untill find the correct measurement.
The mechanical parts I checked too and I have saw no slack.
I got the information with the customer and the equipament showed the problem again . It is like the machine lost the parameters I don't know exactly.
Do you have new advice to me about the problem?

[Al_The_Man]

If the control still has in fact the parameter you last entered but the error has returned, I would say that there is something mechanical changing, or slipping, if the machine has planetary gear reducers, I would check these for wear and also the condition of gear rack, especially the spur gear itself.
Is the travel always less than the commanded move or greater than what you command?
Al

[Alex S.A]

The travell is less than what I command.

[Al_The_Man]

I would see if the change is fairly consistant, measure a long travel move repeatedly about 10 times and measure each time to see if there is a change, I would still tend to check the mechanical wear situation. make sure nothing is slipping etc.
Al