position inaccuracy at high feed rate

[ethanbrush]

We have a vmc 15 that is making significant errors at feed rates of 150 ipm. What we are doing is making a vacuum chuck out of a plastic material with .100 grooves. Because of the soft material we cranked the feed rate up to 150 but noticed that at the junction of the grooves the dimensions (width) of the grooves go to crap. I redid the piece with a feed rate of 30 ipm and the piece was fine. I am new to cnc machines, are high feed rates while making turns like I am doing usually a problem? We did recently have the keyboard board go bad and upon replacing that and getting the machine back up and running noticed that the rapid traverse rates did seem a bit faster than I remember, but I cant imagine the keyboard board would effect that. Looking for input as to whether I am am just exceeding the limits of the machine or there is a bad setting or parameter? I adjusted the backlash parameters several weeks ago and ended up raising most of them by 3 tenths.

Thanks for any input

[Perfect Circle]

Make sure you have the lookahead function turned on.

[Andre' B]

Originally Posted by ethanbrush I am new to cnc machines, are high feed rates while making turns like I am doing usually a problem?

If the servos and/or the control are slow then yes.
http://www.geonicsinc.com/reference/Hot_Zone.pdf
http://www.geonicsinc.com/reference/...Look_Ahead.pdf

[Neal]

Ethanbrush--
The Fadal control will start to loose tracking at that speed. You might look at the M94 and M94.1 codes for help. Also possibley the G9 as a last resort. Another code to llok at would be the G50.1 Ramp Slope control.

Neal

[ethanbrush]

Great thanks for the leads, Ill check into them

[jvangelder]

G50.1 similar to a G05.1 P1 or P0 ? I use G05.1 whenever i do anything over 40imp where im finish profiling on a few fanuc VMC's at work, we have a couple Fadel's however im not sure if i have a G50.1

-Jacob

[Hennessy]

I have run in to this same problem on my VMC-15 XT. Helical boring cycles are about the only thing that i found to cut cycle time and not scrap parts. I think 150.ipm is just to fast on this style of machine. Generally i cant hold +/- .005 at > 50. to 55.ipm. But if you figure something out i am all ears. the machine is accurate as hell but i wish it was faster to it would be nice to know what you figured out.

Hennessy

[ishaham]

Originally Posted by ethanbrush We have a vmc 15 that is making significant errors at feed rates of 150 ipm. What we are doing is making a vacuum chuck out of a plastic material with .100 grooves. Because of the soft material we cranked the feed rate up to 150 but noticed that at the junction of the grooves the dimensions (width) of the grooves go to crap. I redid the piece with a feed rate of 30 ipm and the piece was fine. I am new to cnc machines, are high feed rates while making turns like I am doing usually a problem? We did recently have the keyboard board go bad and upon replacing that and getting the machine back up and running noticed that the rapid traverse rates did seem a bit faster than I remember, but I cant imagine the keyboard board would effect that. Looking for input as to whether I am am just exceeding the limits of the machine or there is a bad setting or parameter? I adjusted the backlash parameters several weeks ago and ended up raising most of them by 3 tenths. Thanks for any input

Dear Fadal User

You are facing the common problem with the Fadal control, cant cut accurate above 20-30 IPM, the solution is live with this or replace the control with the Numatix control, ~$20,000, this control will cut your part accuratly at 150IPM all day long guaranty or yout money back

[ishaham]

Originally Posted by Hennessy I have run in to this same problem on my VMC-15 XT. Helical boring cycles are about the only thing that i found to cut cycle time and not scrap parts. I think 150.ipm is just to fast on this style of machine. Generally i cant hold +/- .005 at > 50. to 55.ipm. But if you figure something out i am all ears. the machine is accurate as hell but i wish it was faster to it would be nice to know what you figured out. Hennessy

You can run your Fadal at over 100IPM and hold under .002 with the Numatix Control, they have a special Fadal kit for $20,000 and guaranty this performance or your money back