SURFACE QUALITY-FADAL

[AREK]

I am using Fadal VMC 4020.Recently for the first time on this machine I have machined a mold cavity shaped as a half sphere.I used DNC. The program was made on Mastercam V8 from a solid model and posted with a proven post processor.The surface after finishing looked like segmented,as if the arcs

consisted of 0.25" straight lines. What is wrong?

[Kenneth Potter]

Tolerance & arc filter settings set to low ?????

 

[gmenzies]

increase your cut tolarance to .0001"

its not the fadal . but having said that. with our fadal 3016,box way machine.

on a g18 or g19 move , we get a small dwell

mark on the transition from down to up move.

it is measurable in tenths.

on the identical move on a okuma,just a line.

i guess thats what a extra 50,000K gets you

[Charles Davis]

As far as the dwell mark goes, try turning the machine accel/decel function off (G8 or G9, can't remember which; check your Fadal manual).

The machine will no longer pause between blocks of code. A negative side effect is the machine will tend to bang against the ways when turning sharp corners. Not that big a problem with surface shapes, where the direction of the cut is changing gradually; except between cut paths. Use the Mastercam Gap Settings, MotionHope this helps.

[gmenzies]

Charles

thanks for the suggestion . but the g8 or g9 plays no part in that move on the machine.

on a 180 degree radius g18 move the ijk determine the movement on our fadal.

the problem i believe is backlash . even though it is a one year old machine . this has been the problem from the start.

the servo motors must change direction .

fadal now comes out with a simens control,that apperantly uses simens servos motors. which allow 3d curves to be machines.

[AREK]

I converted arcs into splines and my tolerances on arcs and filtering were set to 0.0002". Surface still came out segmented.

By the way can Fadal control handle Nurbs?

Fadal dealer says definetly yes,with 300 blocks read ahead. I know there ars shops using Fadal for mold making ;I would like to hear from somebody with this kind of experience on Fadal.

[SVO]

I hate to sound negative, but we had 2 brand new Fadal 4020's purchased for the sole purpose of contour milling a particular mold package. Dwell marks, backlash, loose gibs, we went through servo motors like candy. Reps from CA came down and couldn't make either one of them machine a true hole. Let alone surfacing with any kind of tolerance. I wish you better luck than we had. We took our losses and spent a little more on better equipment.

[Guest CNC Apps Guy 1]

OK friends, here's the deal. What he's seeing most likely is the pitch in the ball screws showing up on his surface machining. Don't fret, EVERY machine will show this if the conditions are right. It usually occurs in large radii machining on contours as well. There's nothing that can be done short of getting a finer pitch ballscrew for your machine. It's not a defect in the machine. It's just the way it is until you get on a machine that has linear motors instead of ballscrews.

James Meyette

------------------

James Meyette