Cutting tool preference for Aluminium

[Boris Ludwig]

Just wondering if HSS as opposed to carbide is the prefered tool for cutting aluminium on a lathe?

I've tried carbide but seem to get a "gritty" or "torn" surface finish on the part. I've tried faster speeds up to 1200 rpm and slower feeds but can't seem to get it to work well. This has been true with boring internal surfaces too.

I've used HSS and I seem to get a better result but I'm wondering if I'm overlooking something with carbide tool use.

Any comments that might be helpful are appreciated.

Cheers

 

[benmychree]

I(f you use carbide, use uncoated inserts, they have a sharper cutting edge than coated; HSS is good too, using a ground in chip breaker to curl the chips; the most important thing as to finish is using a cutting fluid, traditionally kerosene was used, but light cutting oil works too (non sufurized) or I use Tap Magic, applied with a brush, water based coolants also work, but oil is best for finishing.

 

[wrmiller]

Some 6061 just looks like crap, no matter what I cut it with. 7075 on the other hand...

I use carbide exclusively on my lathe, and have found that the polished 'aluminum only' inserts work really, really well. Careful with them though as they are near razor sharp as I soon discovered when I ran my thumb down the edge of one!

They also work really well for steel, but I only use them for finishing passes so as not to damage the cutting edge.

 

[mikey]

Boris, if you want to stay with carbide, try the SCLCR tool holders with a CCGT AK insert. They are ground, polished, have a chip breaker that actually works and will give you the ability to rough heavy while also producing a fine finish with lighter cuts. The same holders will also take CCMT inserts for use with most other materials. For aluminum, this is one of the best inserts I've seen. I tend to run these AK inserts as fast as my lathe will go and have had very good results.

A well ground HSS tool will do as well or better (better in my opinion) if you get the geometry right.

I use both kinds of tools but 90% of the time, I reach for my HSS tool.

Hands down, the best cutting fluid I've seen for aluminum is Relton's A-9. WD-40 works pretty good, too.

 

[Hawkeye]

I often use Crisco to lubricate aluminum. Brushes on with an acid brush and stays in place, until it gets hot, then flows like oil.

 

[wrmiller]

I recently received PM's lathe tool and boring bar setup (BXA) that takes the CCGT/CCMT 300 series inserts. Set comes with inserts for aluminum and steel. And I only have to remember one size/config of insert when I need more. Those insert charts make my brain hurt...

 

[Boris Ludwig]

Thanks, that's all helpful. I'm going to try those suggestions and report back with my results in case I'm doing something wrong.

I often use Crisco to lubricate aluminum. Brushes on with an acid brush and stays in place, until it gets hot, then flows like oil.

Isn't Crisco a blended vegetable oil for deep frying potatoes? LOL
"......many ways to skin a cat" still holds true!!

 

[Z2V]

I guess the garage shop would smell better like french fries than kerosene

 

[wrmiller]

Thanks, that's all helpful. I'm going to try those suggestions and report back with my results in case I'm doing something wrong.



Isn't Crisco a blended vegetable oil for deep frying potatoes? LOL
"......many ways to skin a cat" still holds true!!

I have Relton's A-9 in my fogbuster and it works well for aluminum, and even mild steel. I guess any cutting fluid is better than none.

Prior to that I kept a small spray bottle of WD-40 on the mill and lathe which works good as well.

 

[coherent]

Any end mills, bit or inserts that are coated generally don't work the best for aluminum. The better chip clearing the cleaner the cut. Cut your tool or buy inserts with a high rake angle. Aluminum is soft and sticky. Coatings tend to grab and gum up the tool bit. I cut a lot of aluminum on a cnc mill and higher speeds and bits with a higher helix that clean the chips make a huge difference. It sounds like you already have but test a few different speeds, especially for the finishing pass. A sharp tool/insert is a must, the duller it is the more it will grab and spall the surface. I also get a better finish when using at least some type of coolant and/or lube. Even air will help some.