Wobble in cut

[ausman]

Hi there,

We have a problem with or Amada FO that has plagued us for some time now & i can't seem to resolve it.

When changing the direction we seems to get a wobble affect on the on the side/edge (best example is that the affect is like dropping a pebble into a pond), the waves are big upon the direction change then slowly fade away as the cut leads out further.
This problem occurs identically any where on the cutting table.
It occurs when changing direction from Y- to X-, however when cutting along Y+ then direction change to X+ it does not occur.

We recently had the Fanuc service Tech in to fix - 6 hours spent checking drive tuning, overshoot/ under shoot, parameter setting and adjusts to tune it out, checked mechanical back lash & there is almost zero on both X (rack)& Y (ball screw) axis.
End result was assurance the problem is not electrical/ controller related.

I have attached a couple of photos of this weird phenomenon.

Any input or suggestions would be greatly appreciated...
Cheers

 

[ausman]

Another photo, sorry for the large file sizes.

 

[JeanFreli]

Hi Ausman
My first thinking is the program you run, I mean the G-code or something like that. It just an idea folks. If the tech guy passed and found nothing wromg on the mechanic stuff.........Hopefully you"ll find something. I'll keep reading the comments...curious about it and can learn more.

 

[ausman]

Hi JeanFreli.

Thanks for you reply, yeah no change with the code. When we fist acquired the machine about years ago the cut was perfect with no wobble.
Cheers

 

[nicknick]

we had the same problem on our amada 2415 it turned out to be two sheared of bolts on the z axis carriage we bought the machine used so who ever had before probably crashed it once or twice. we had techs install and look everything over they said it was just a old machine. i ran it probably 6 months like that til i got persistent about it they finally figured it out. now i have no wobble. edge settings will help if you can slow it down but who likes to slow down. good luck

 

[LASERNINJA]

I am leaning toward the cutting head as well. If it only happens on high pressure gas, clean cut, then that is a good indication.

If I remember, Your machine has that funny U axis on it. Would you mind posting a picture of it?

 

[ausman]

Hi NickNick & laserNinja,

Thanks for you help, I had checked the head previously but however I was not very through, simply just trying to wiggle the head around to check the movement but nothing stood out.
I will do a more through inspection on the head assembly & mounting to the linear rails & see if I can see anything out of the ordinary.

The wobble occurs when cutting all materials at all gas pressure ranges, if the feed rate is below around 1300mm per minute then the wobble is gone or if i use the edge codes (slow down around corners) or exact stop code then the wobble is completely gone.

The machine doesn't have a U axis, just X,Y,Z & B (focus lens) + the pneumatic AO mirror.

Cheers

 

[Foostrap]

Definitely looks like a vibration issue (either axis vibration or plate vibration). Is your machine is not flying optic, make sure the plate is not moving. Make sure it's not the lens that is loose (had that once). If possible, slow down the acceleration of the machine; if vibration goes away or is less, definitely an axis issue.

 

[ausman]

Hi Foostrap,

Thanks for your advice, machine is flying optic so the sheet is always stationary.
I'm still checking the head and will also check for vibration as well.
We did spend a few hours checking the head last week. however we found nothing out of the ordinary
Cheers

 

[Chally72]

Slowing down the cut speed as Footstrap suggested would give you an indication as to where the waviness is coming from.