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beanbag
10-18-2009, 05:20 AM
Having problems creating long stringy tangles of aluminum on the lathe. I've read that to get more "curl" on the chip (which causes it to hit something and break into pieces) you should use more feed. However, I'm not using a CNC to do production level work, so I tend to use relatively low feeds. I really have no desire to blast thru the workpiece.

I'm using carbide inserts for aluminum, and while they have a nice long ramp, the chip just gently slides down it, and then makes these big curls about 1 cm diameter which shortly turn into tangles.

I was wondering if there are any aluminum inserts that have a very short / close chip breaker, or whether I can add one on by sticking something part way down the ramp, to cause the chip to curl up faster.

Bguns
10-18-2009, 05:25 AM
Why carbide?
Non production..
Wear is not an issue...
Speed is not an issue...
Just grind a HSS tool with a chipbreaker that suits, and proceed on...

http://books.google.com/books?id=WCYDAAAAMBAJ&pg=PA150&lpg=PA150&dq=chip+breaker+for+aluminum&source=bl&ots=uNUkYZUkKx&sig=_9zeqjfwBx2R2VqAJqt8BXbWwas&hl=en&ei=jdHaStOMDYjWtAO3x9XJBQ&sa=X&oi=book_result&ct=result&resnum=2&ved=0CBAQ6AEwATgU#v=onepage&q=chip%20breaker%20for%20aluminum&f=false

Proper insert and holders are out there for aluminum turning, but why speed $$ when a simple HSS cutter will do EXACTLY what you need...

jeepnxj96
10-18-2009, 10:10 AM
try a heavier DOC @ your current SFM, you can get better chip formation and it should break up better. or try leaving your DOC the same and run higer SFM. either one should create a better chip that breaks sooner into smaller more manageable pieces. insert doesn't care if it is production or not, just how they are designed:D

beanbag
10-19-2009, 06:53 AM
Thanks for the link to Popular Science Magazine. It's neat to see how things were done "before my time". I actually do have some sticks of HSS laying around, but I never got around to grinding them since I am always cutting at different angles. A few years ago, I did grinding of HSS for lathe work, but I didn't know what I was doing back then.

Today I tried a different carbide insert I remembered I had, namely a Mitsubishi insert with a chipbreaker on it. It's a little raised ridge about 1 mm back from the cutting edge. This at least made much smaller curls of chips, namely 1/8" or so, and sometimes the chips would even break. Mostly, they shot out as compacted balls, which is still a lot better than before.

Now that I think about it, the previous insert I used had a pretty large nose radius. That also might have something to do with it.

Black_Moons
10-20-2009, 08:45 PM
for a lot of those chip brakers you need the depth and feed just right. And by just right I mean agressive.

If you have a 12x36 or similar, your not doing it any good by taking a dozen passes to cut off 0.1" unless the workpeice is too thin to support that much cutting force.

Try chucking up a 1"~2" diamiter peice and take off 0.1" in a SINGLE pass! (0.05 depth of cut)

In aluminum on my 12x36, with lube driped over the peice, iv done 0.1" deep cuts and it just loves it.

When its that deep, the chips tend to be too thick/brittle to curl much and snap, you end up with a shower of scalding hot chips (If your doing mild steel with carbide, you can end up in a shower of scalding hot chips that turn blue apon contacting air)

the long curls arnt that bad, because if they do get caught on something they tend to snap easily

Whats INCREDABLEY dangerious is when it forms a long string that ISENT curled up, those are VERY strong and often razor sharp and can wrap around you or controls and get yanked in by the chuck with much strength. Be very careful when your lathe produces this type of chip.

gr8life
10-21-2009, 12:46 AM
Look over on the Home Machinist site there is a long string of posts about chip breakers. Deep & fast is the answer. If you really want to remove alum. I have an Iscar carbide bit on my Grizzly G4003G that will remove .350 depth of cut
.0048 per rev feed rate @1000 rpm and you will never see anything but little curls that look like 9999's. If you are interested let me know.
ed

EVguru
10-21-2009, 06:18 AM
I can't remember what the part was, but I was using the very worn and abused Myford ML7 at work to turn down a big lump of Aluminium. I recall making up a hook with a handle and walking backwards down the 46 foot length of the workshop pulling the swarf and then jogging back to the lathe to hook another length. I think I got to seven lengths by the end of the cut.