View Full Version : Newbie question on lathe tools

02-06-2005, 04:17 PM
Okay, this is almost too basic, so jump on me if you want to. I thought I had lathe tooling figured out, but I keep reading conflicting info and getting opposite advice from people. As I understand it, HSS tooling requires lubrication, oil or synthetic, for any ferrous metal. However, our instructor always cuts aluminum dry with HSS. I have also been told to use WD40 for aluminum and HSS.

He also cuts ferrous dry with carbide. But they use indexable inserts in his shop and throw them away. I have welded carbide and want to keep them longer. Should I use lubricant with C-5 and C-6 carbide tooling on ferrous? What about aluminum with C-2 carbide tools? I have got all kinds of opposing views from people.

What about bronze and brass? Or cast iron?


02-06-2005, 04:31 PM
You don't have to use lubrication with HSS. You may (or may not) get a better finish if you do; the cutting edge will probably last longer if you do. But the Machinist Cops aren't going to come bust your shop
door down if you don't.

As far as aluminum is concerned...that somewhat depends on the alloy you're talking about. Kenemetal's "Microchip" alloy for instance, desinged for machining, cuts really well druy. Some alloys are so gummy, however, some sort of lubrication is virtually mandatory to keep the chips from welding to the toolbit.

Brass and cast iron are generally machined dry. Cast iron dust + oil tends to make a dandy lapping compound, which you don't want. It also makes a gummy mess. Bronze is also generally done dry, I think, although that may again depend on the particular alloy you're talking about.

I use very little carbide tooling, so I can't address those questions very well. It's my understanding though that in general, cabide has to be either "drowned or dry." If you use intermittent lubrication, the resultant uneven heating can crack the cutting edge. Mostly though, dry is fine.

02-06-2005, 05:46 PM
Nice answer. And as you can see there are very few hard and fast rules. Always test first if you can and then do the real thing. Try to keep a logbook of types, feeds, and speeds. If you categorize by metal alloy you will be able to search more quickly to relevent information. There is a very smart poster to this board whose website is chock full of stuff. "MKlotz" I believe.

02-06-2005, 11:57 PM
Don, run carbide inserts 99% of the time, make special cutters from HSS as needed.

Run a vortex air-cooler on the mill with carbide inserts, solid carbide tools, and cobalt tools, as it blows chips away from the cutter.

Normally run the lathe tooling dry, even when taking maximum roughing cuts at highest SFM, on mild steel and cast iron.
Aluminum will easily chip-weld with aggressive feed/speed, lubricant helps.
Use lubricant on stainless as it gives me a better surface finish, especially when boring.

I use a vegetable oil called Accu Lube LB2000 (most industrial suppliers have it).
Smells like fish frying (on hot stainless), dog loves to lap it up, makes her coat look shiny. Expensive as hell, $70/gallon, but you don't use much. Still got 1/2 a gallon left after a year.

Barry Milton