Need Help!- Aluminum part off issues.

[fizzissist]

We're all missing something very obvious here......It's something stupid simple. Has to be.

Could you post some pics?
1. Close up of the blade installed in the toolholder, installed in the turret.
2. Close ups of the insert, top, side, front, oblique
3. ... Face (manually, using handwheel) maybe .01" off the bar with the tool, stopping feed in X so that a .01-.02 nub remains... and take a close up so we can see the surface finish on the bar side, and where the tip is relative to the CL (not that we think you're fibbing about the CL.... we just wanna see)

This problem is pissin' me off, and I wanna see you with a happy cutoff.

[jimmyjolly]

Where is the material sourced from? We use a huge amount of 6061 t6 from varying suppliers, we have found certain batches coming in from china to be right on the limit of the t6 temper making it almost impossible to cut, just gums up and even using steel tips and insane feed rates cannot get any chip breakage. I would suggest trying another supplier for your 6061 or failing that, can you get away with using 6262 t6? It anodizes well, has similar shear strength and machines like a breeze!

I would try and bump up the concentration of your coolant mix too, always helps on aluminium, and if you are having trouble with chip breakage, use a more negative steel insert, just steer away from TiN coatings.

Another thing, is the coolant directed onto the tip the whole way through the cut? Probably sounds like a stupid question, but coolant flow is critical for parting, make sure you have a consistent flow the whole way through the cut.

Hope you have some luck!

[neilw20]

Try some WD40 or kerosene from a spray bottle.
Your chips are screwing out crooked so tool is not square, or forces are causing misalignment. Chip exit path on top of tool must be smooth.
0.002-0.003 per rev. Front clearance 3-4°. Top rake at least 5-6°. VERY sharp.
If the machine can't take the force and deflects use a narrower tool so the deflection is less because of lighter load.
Chips screwing sideways are damaging the face.

[PixMan]

Walter makes a single-ended insert designed specifically for parting off aluminum. It looks nothing like the CF6, CF5 or CE4 shown in their video that was posted. Nor does it look like any other insert made by any other company. It is the CK8 chpbreaker, available in the FX2.2, FX3.1 and FX4.1 size single-ended inserts and in only the uncoated grade WK1. It fits only in their 26 and 32mm tall "XLCFN" blades (so far as I know.)

I've tried almost every parting tool known to man, from hand-ground HSS tools to various single and double-ended inserts. Nothing else seem to work quite so perfect!

[bob1112]

Sorry guys, been busy with work and kids.. Coolant is at 6% and carefully aimed to supply coolant inside the cut.

Something to consider, I am running the blade as LH and M4. I do believe the holder block is reversable and the insert does come up to CL but something I should add I guess.

I will work on some pics. I have a couple jobs that that need my attention on the mills but I DO want to work this cut off issue out on the lathe. Very much appreciate the help from you guys! I cannot help but think it is something simple that I am missing here. Going to be irritated/happy when I find it!

[littlerob]

I hate to be that guy that suggests you buy a new tool holder, because I often think to myself "hey I just gotta get through these parts a$$".

But I never use part off blades, unless absolutely necessary. I use groove/turn tool holders, and at that diameter you might want to think about it. You have much more control over what you want to do, even if it still sucks you can leave stock for a finish pass like fizzissist suggested, but I can never get it to work with a part off blade.

Robert

[bob1112]

I was close to abandoning the blade but would have to replace them with multiple single ended holders because I adjust them a lot for the most rigid setup. There seems to be several people using them without issue which is damn frustrating. Been working with mills for years and know feeds/speeds pretty well and just cannot find a spot where the blade works. Even the inserts were confirmed to be specifically ground for Al but I still think the major issue is they are dragging on the sides for some reason. I just don't think another holder will help but I will see if I can find another in the shop to try.

I do have a tool rep coming out on Monday WITH some other "expert". I told the guy if he does not have experience, this is a wasted visit because I have done about everything any machinist would know to try. maybe we can find the issue.

[littlerob]

Originally Posted by bob1112 I do have a tool rep coming out on Monday WITH some other "expert". I told the guy if he does not have experience, this is a wasted visit because I have done about everything any machinist would know to try. maybe we can find the issue.

I love those visits (not), I spent 3 hours with a guy last week whose tool failed again and again. You haven't tried everything, otherwise your parts would be coming out the way wanted, sorry. Even the video that was posted was not a part off blade it was a grooving tool. There is so much deflection with a part off blade, that is why you were getting convex part shapes before.

If you are going to stick with it though, here is some geometry knowledge: the geometry of the insert on a part off tool is designed to make the chip curl up on the flanks, making the chip narrower than the groove itself, allowing coolant in and allowing the chip to get out. The key to making that work is pushing the tool hard enough to generate that chip. I don't care much about SFM when parting, go low it will generate less heat, but feed is important, .005 in AL is no big deal.

But if you can find a groove tool that will do it that is where my next step would be personally.

Robert

[UniqueMachining]

Bob1112

At 3:49 in the 2nd video (should not look like this), I noticed significant deflection to the left.

Had a similar problem and discovered that the tool was radiused on one side only and when mounted in the holder it cocked it slightly, causing it to wander. The tool was designed to be used at one end only. Of course I was using the wrong end.

Have also had this happen when the tool is not exactly perpendicular to the work.

John

[bob1112]

Originally Posted by littlerob I love those visits (not), I spent 3 hours with a guy last week whose tool failed again and again. You haven't tried everything, otherwise your parts would be coming out the way wanted, sorry. Even the video that was posted was not a part off blade it was a grooving tool. There is so much deflection with a part off blade, that is why you were getting convex part shapes before. If you are going to stick with it though, here is some geometry knowledge: the geometry of the insert on a part off tool is designed to make the chip curl up on the flanks, making the chip narrower than the groove itself, allowing coolant in and allowing the chip to get out. The key to making that work is pushing the tool hard enough to generate that chip. I don't care much about SFM when parting, go low it will generate less heat, but feed is important, .005 in AL is no big deal. But if you can find a groove tool that will do it that is where my next step would be personally. Robert

LOL, the visit was a waste of time. Typical sales visit. 30sec talking about the problem, then the book comes out showing me what I should buy. I am turning tight clock springs which cannot be that far off.

I would not mind running a groove tool for parting but I have been warned before that groove/turn tools and inserts are expensive and to use a cheaper cut off for that dedicated op.

I am seriously lacking anyway in lathe tooling and really looking for a line that is reasonable and works well. I am running TMX WNMGs with high polish inserts for Al and really liking them. The rep that came in sells Kyocera which I am not familiar with. 30 bucks/insert is not in my budget.

[tmcallister74]

I hate to say this, but Kennametals part off stuff works awesome. I was never a fan and fought it for a long time but I had to eat crow. It works and works well. Get a rep in there and find out.

[littlerob]

I use iscar, I don't really have the budget for it either, but the investment has paid for itself 100 times over. Plus availability is important to me, iscar is available through MSC and next day is good for me.