Chip Breaker for Aluminum?

[epanzella]

I've been doing all steel since I got my lathe a few months ago but just started a project in aluminum. I have some inherited HSS tools that appear to have chip breakers and have some indexable carbide with chip breakers. These both work great on steel with manageable chips that I can pick up with my shop vac. Last nite I started turning aluminum and no tool I had would break the chips. I tried DOC of .030, .050, and .100 and all produce a bushel basket sized cloud of concertina wire with each pass that scares the heck out of me, particularly when it gets snatched by a chuck jaw. The lathe cuts all three DOCs smoothly with a good finish but the swarf seems pretty dangerous. I ended up using a 12 inch long nose pliers to rip away the chip every few seconds to keep it from looking like a monster movie but there's gotta be a better way than this. Is there some special way to break aluminum chips that's different from the way steel chips are handled?

 

[Bill Gruby]

This will get you started. I don't use a chip breaker for Aluminum, I use a steeper rake angle.

"Billy G"

http://www.steves-workshop.co.uk/tips/toolgrinding/toolgrinding.htm

 

[Halligan142]

I use a half moon nick on the cutting edge. Check out this video. Fast fwd to 20:00 unless you want to watch the whole thing. https://www.youtube.com/watch?v=sFnTXgXMbrQ

 

[Ray C]

Also keep in mind that some chip breakers have a range of DoC where they work the best. Many will do nothing until you get over 15 thou then they work fine up to 35 thou then start making long (dangerous) curls beyond that. You're taking some pretty deep cuts. How much stock do you need to remove? Anyhow try 20 or 25 thou or maybe try a different brand of insert with a different breaker style. Is the breaker getting packed-up and clogged?

Anyhow, aluminum does tend to birdnest so, you're not alone.

Ray

 

[Tony Wells]

Sometimes it's the alloy. Pure aluminum is very soft and very ductile, both properties that work against chip management. Other alloys are less so, and easier to get a chip to break. And it's not all about DoC, feedrate has a tremendous bearing on breaking chips. Speed also, as warm or hot aluminum is more likely to bend than to break. Coolant and high speed and feed often break a chip fairly well in the common alloys of aluminum.

 

[epanzella]

I use a half moon nick on the cutting edge. Check out this video. Fast fwd to 20:00 unless you want to watch the whole thing. https://www.youtube.com/watch?v=sFnTXgXMbrQ

Thanks. I'll try that half moon cut.
Ed P

- - - Updated - - -

Sometimes it's the alloy. Pure aluminum is very soft and very ductile, both properties that work against chip management. Other alloys are less so, and easier to get a chip to break. And it's not all about DoC, feedrate has a tremendous bearing on breaking chips. Speed also, as warm or hot aluminum is more likely to bend than to break. Coolant and high speed and feed often break a chip fairly well in the common alloys of aluminum.

I was cutting dry. 600 rpm, .0038 feed rate, DOC .030, .050, .100 Finish was excellent. My only complaint was the huge ball of swarf. I'll try some coolant.

- - - Updated - - -

Also keep in mind that some chip breakers have a range of DoC where they work the best. Many will do nothing until you get over 15 thou then they work fine up to 35 thou then start making long (dangerous) curls beyond that. You're taking some pretty deep cuts. How much stock do you need to remove? Anyhow try 20 or 25 thou or maybe try a different brand of insert with a different breaker style. Is the breaker getting packed-up and clogged?

Anyhow, aluminum does tend to birdnest so, you're not alone.

Ray

I had to take an inch off a 3 1/2 inch cylinder. The whole tool tip does get buried in the swarf sometimes and when that happens it will periodically get sucked thru the cut making a dull spot in the finish. I don't have much for tooling with only one kind on carbide inserts and a handful of hand-me-down HSS bits. Thanks for the info, Ray
Ed P

- - - Updated - - -

This will get you started. I don't use a chip breaker for Aluminum, I use a steeper rake angle.

"Billy G"

http://www.steves-workshop.co.uk/tips/toolgrinding/toolgrinding.htm

Good info, Thanks.
Ed P

 

[bret4]

Like one person mentioned. It can depend on the grade of aluminum. Your feed rate can go up to .010" or .012" per rev at .015 to .030" per side. Also using a cutter with a .015 to .030" radius. Just leave .005 or .010" for a finish cut at around .003" per rev.

 

[Mid Day Machining]

Chip breaking in aluminum depends on what alloy you are cutting. 6061 won't break. 2024 and 7075 will make nice little popcorn chips.

I might add though, whether or not your chips break depends on your depth of cut, spindle RPM and your feed rate.

 

[Chipbuff]

I feel your pain! I do a lot of alum. projects and there is no one good answer. Material, speed and feed are variable. I have never gotten chips from 6061 at any speed or feed. I use the needle nose pliers method. I do turn most alum. stock around 900 rpm with good results. I do agree with taking more reasonable cuts of .025 to .030 and then using a light finish cut with a slower feed. I get really good, smooth results doing this. I turn a lot of 1-1/2" tube for model rockets and it works very well. Good luck with your project.

 

[epanzella]

I feel your pain! I do a lot of alum. projects and there is no one good answer. Material, speed and feed are variable. I have never gotten chips from 6061 at any speed or feed. I use the needle nose pliers method. I do turn most alum. stock around 900 rpm with good results. I do agree with taking more reasonable cuts of .025 to .030 and then using a light finish cut with a slower feed. I get really good, smooth results doing this. I turn a lot of 1-1/2" tube for model rockets and it works very well. Good luck with your project.

I bought this hunk of aluminum a long time ago for another project but I think it is 6061. I guess I'll have to keep my needlenose handy.
Thx
Ed P