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looking to find the cause of the swirl marks on faced part on cnc mill

souvik

Plastic
Joined
Jun 23, 2018
I recently bought an Indian made BFW BMV35+ cnc mill with fanuc 0iMF control. Swirl marks on one side of the part . part was symmetrical and supported symmetrically. is it manufacturing defect of the machine. like z axis not perpendicular to the x-y . but if it is so why one side is clean. the material is EN31 steel.

images attached. Thanks.
 

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Looks like edge build up, chip dragging, or insert failure to me, rather than any machine problem. What condition were the inserts in when you were done? Was the coolant obstructed on one side?
 
I agree with the guy ^^ up there. As much as I hate to ask I'm going to anyway. Did you sweep the head with an indicator to see if it was out one way or another?

Brent
 
the spindle runout is about 2 microns

hi gregormarwic, the inserts were new kyocera made BDMT11. and after the run it has seemingly no wear.

hi gregormarwic,
the calibration sheet that came with the machine says runout is 2 microns. my dial test indicator does not even seem to move when i measure runout in the taper. so spindle is pretty accurate. I'm not sure how to measure the axis deviation of the spindle. Should i put on a long tool and drag the indicator by z axis through its sides.

I'm not so expert. A little help will be appriciated. I want to be sure before calling their engineers.
 
Did somebody turn the feed and possibly the speed WAY down for the right half of the part?

Looks to me like it slowly smeared its way around. I don't think you would get full circles
like that unless the feed was really really low.
 
feed and speed was constant, i myself runs the machine

hi Bobw,
the spindle speed was 1600rpm and feed was 800mm/min for a 20mm 3 insert kyocera endmill. and the knob was at 100% all the time
 
Almost looks like washed out ball screws on XY. Check your backlash. Might have some adjustment left.

Sent from my SM-G950U using Tapatalk
 
Only reason I say backlash issue is because of the stall marks as is works through the radius. Had same results from an old FADAL I had, when it got to corners.


Sent from my SM-G950U using Tapatalk
 
hi johneezreno,
it is a new machine (2months) with THK made ballscrews, and i think backlash should come to play only during direction change. but there are marks on straight paths too . see.
 
Backlash corrects itself as it moves. A cutter will force a table one way and the machine will overcompensate if the setting is wrong. That will give stall marks. Or could be your program. Say for some reason the post that was output to your machine had several movements in a straight line could cause pause marks too.
Like
G1 X1Y-4
X1.5Y-4
X2.0Y-4
X2.5Y-4
and so on. Think it's called scaling.
Although it's a straight line, all the extra code causes pause.
If this machine is a "New" purchase, I'd be on the phone with who I bought the machine from, telling them to come fix their machine. Based on picture of swirls we'll also need pics of the cutting tool, and program. There is slop somewhere. Those are bounce or pause markings. Not familiar with machine brand or name. So depending on how ridged the machine could have bearing as well.

Sent from my SM-G950U using Tapatalk
 
hi johneezreno,

I think i will have to call their service engineers on monday to come and see. I wanted to make sure the problem is not mine. and dense g codes should not pause the machine as it has aicc 2 with 200 lines lookahead. i do a lot of small diamater ball end mll tool job for die molds with millions of lines of codes. the cycle time comes within 99 to 98% of the computer estimate.
 
I vote for tool defection and chatter/ poor tool choice. Is the model w/o the tool changer? The inserts may look good but that doesn't always translate to "good" when they are balls deep in a cut. If I'm wrong try to get your money back
 
hi Aejgx6,

The model has tool changer, but as i do die mold work, i do manual tool changes.
Any suggestion why only one side of the part is affected?
 
It could also have something to do with the workholding. Clamping plate material can be tricky.

Was the left side machined first and the right side machined second?
 
Maybe by the time the tool gets there, heat build up causes something something like a fixture or tool holder to expand enough to be problematic. Try face a large test piece with a different tool. Start slow and crank her up to ears pinned and full steam ahead and see when the problem surfaces. I.e. Change one variable at a time until the problem disappears.
 
Does the tool path need to be so complicated for what appears to be a simple facing operation?
 
actually i hasd clamps on the sides which i needed to avoid to i modelled them. so the software created toolpath around the clamps
 








 
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