Facemilling A360/380 diecast parts, I think I'm getting occasional chip welding?

I'm machining some die cast aluminum, 360 or 380 material, approximately 3" x 7" x .400" thick.

I'm bolting through 3 holes that are already cast into the part. I'm holding at those 3 points with pads underneath the part, the rest of the part is not touching anything. There are 2 adjacent holes spaced 2.3" apart on one side, and 1 hole in the middle on the other side of the part, 6" away from the 2 adjacent holes.

The part is bolted to a fixture in our horizontal, and I'm using a 4" (and tried 3") iscar facemill, octogonal inserts.

I'm trying to achieve a 125ra surface finish and hold .0005 flatness. Both of these are easy to achieve (usually)

The problem I'm having is, occasionally (once every 2-10 cycles) I will get "gouge marks" from the facemill, in random places in the travel (it is facing in the y axis, due to how I have to hold the part). I run 2 parts per cycle. Sometimes these gouges are in the part on the left, sometimes on the right. The parts are tight, when watching it, there's no noticeable chatter, nothing on the machine is moving (tool changer, for example).

I've tried the following:
alumimum specific sharp carbide wiper insert, 1 insert, 4" feedmill (treating it like a flycutter, basically), both dry and with coolant
aluminum specific sharp carbide inserts, 1 insert, 4 inch facemill, dry and coolant
alumimum specific sharp carbide insert, 6 inserts, 4 inch facemill, dry and coolant
general purpose insert with honed edge, 6 inserts, 3 inch facemill, dry, coolant, and dry with airblast


I'm only removing about .02" of material as that is all that was given.

I've tried all of the above with different amounts of cut, .02 all at once, .018 and .002, .015 .004 .001, etc.

Currently, my "best" setup is with the 3" using honed inserts, dry with airblast. But 10 cycles isn't great.


The "gouge marks" are less than .001 deep, as a .001 deep skim pass gets rid of them 90% of the time.



Does it sound like I'm getting a chip stuck to the tool? Would it drag a chip under it like that? The only other thing I think it might be is the part getting "excited" in the middle and vibrating momentarily, but I've never heard a sound out of this operation and it is sometimes near the entry or exit, where it would be the most rigid.


Ideas? Diamond tipped insert perhaps? other ideas? I'm all ears.

Does appear to be dragging chips from the description - or you are getting BUE on one of the inserts. Diamond would definitely be a plus in this situation.

Maybe you're dragging on the exit, like th e spindle isn't perfectly square to the setup? Do you have thru spindle coolant as an option? Have you tried a shear hog? Diamond would probably do it, but you should be able to pull this off without that extreme of a step.

thanks for the replies, guys. Don't think that I didn't notice them a week ago.

So, its been a week, I tried some stuff and found out the solution to my problem.

First, I had grabbed the only diamond inserts we had, mounted it on a boring bar, and stuck the boring bar in a flycutter body. The finish was okay; the insert had a tiny radius so it wasn't that great. Anyway, it didn't really work for very long (5 pcs) before it happened again.

Bought a couple inserts from Iscar (adkw150508 id5), and mounted a single insert to a 4" facemill. Gives a beautiful finish. But after about 5 pcs, it did it again.


I guess the one detail I didn't give was that it is a '93 Leadwell H400... older linear way machine, pretty used and abused over the years, and not the most rigid of machines. And while I KNEW that nothing was moving automatically (such as the tool changer, or even the chip augers/conveyor), it wasn't until that cycle that I had an idea.

The operator loads one pallet while the other one loads. And then I wondered, could it be vibrations from loading one pallet while the other is cutting? I put it to the test. I put an M00 after the first tool, and have the operator load the other pallet fully before hitting the cycle start button so the second tool (facemill) can go.

We've now ran about 60 cycles without a single gouge in any part.


Just for shits and giggles, i threw an indicator on the head and touched the pallet inside the machine and could get it to move .0005 each way just by turning/locking/pulling on the pallet outside of the machine

I'm going to give the machine a good level and tram after this job is complete, making sure all the feet are on the ground. For now, we're making good parts.

Had a tow motor going by once or twice a day causing me a mystery bad part once or twice a day. Literally took MONTHS to figure that one out. Also caused by a non-weighted foot on the machine.

dandrummerman21 thanks for posting your follow up. It'll be interesting to hear if the machine had settled out of level.

Well, I assume the machine was not trammed in very well when we got it about 4 years ago. It was a notch out of level in x, but the table was pretty good in z.

Y is out of square in the yz plane to the table about .001 over 15", tilting away from the pallet as it goes up, which is good enough for what we use the machine for (generally), xz plane looked pretty good.

The spindle is tilted down, It is out .004 over a 10" circle. I believe my only recourse on that would be to shim the skates and/or ways, and I'm not about to do that!


After I checked that, I checked the feet, 2 of them were just loose, and one foot was missing a pad. one was near the pallet loading station, and it did help bring the machine into level along the x, but it did nothing to correct the issue where the machine inside moves when loading a part. (you kinda have to be forceful to get it to move inside, but it still moves .0005 either way).

Its a pretty light weight machine, so I don't think there's much I can do. I'll leave it as is, and I'll be aware of it when setting up future jobs.