[erd39030]

Our horizontal machining center, Haas EC-400,
leaves a rugged finish when it is going downward (-Y axis).

Leaves a good finish when going up (+Y), bad going down (-Y)

What I've been doing so far is reducing feeds and depths
but I wonder what is causing this?

Is this behavior common in HMC's? or is something wrong with the machine, set-up or programming?

I first thought it was due to high overhang tools,
but now, since I used the same tools in the VF2, VMC with good results
I am thinking there is something wrong with the ballscrew, servo parameters or the holy spirit that insuflate life to the CNC machines.

Any ideas?

Thank you:
Everardo Rascon

[Machineit]

You say Y+ and Y-, but are you plane milling or climb milling? That may be the reason.

[erd39030]

I use climb milling.
In fact, the poor finish i get is like the finish I would expect when doing climb milling in a manual machine without ballscrews,
It is not shatter.

[MIKEL12]

Have the same problem with ours, if you figure something out i would like to know about it.

This is rework of some parts from our lathes, stickout is quite large. but i doubt it would have been a problem in any of our other machines.

https://youtu.be/DEb3xsYxxnI

[HFO Tech]

Could be backlash in your y axis ballscrew.

[MIKEL12]

Not sure but seems that this might be solved for us, or at least greatly improved.
Air amplifier that is part of the pallett retention was set to low from factory, (120 psi), according to what i could find in the manual it should be set at 140 psi.

After increasing this and doing some test runs it seems to be running better.