View Full Version : Using TNMA 434 inserts/General carbide help

08-10-2003, 04:06 AM
I'm new to inserts and understand that the positive rake inserts are probably best for most HSM projects but I was the only bidder on a lot of TNMA 434 C-5(AN-6) grade inserts and want to make some toolholders for the lathe...I was able to decode the the measurements of the insert easily enough, but I thought I'd seek some guidance before I start.

Is there anything wrong with using carbide for cutting aluminum?

I'm currently using a Southbend light 10" (10K) lathe with a 1/2HP motor...Do I even have the HP for the 1/16" radius on these inserts?

These are 0 rake inserts with a straight through hole and no chipbreaker...That means I can cut on both sides right?

I might make a jig and grind a little clearance into the inserts (If I can't win an auction on some postive inserts)...There's nothing wrong with grinding inserts right?

Should I make the first test holder with 0 degrees or should I put some rake into the holder to compenstate for deflection?


08-10-2003, 03:42 PM
Yes you can use both sides - but note that is one side is damaged or has BUE you will not be able to use it unless the side is lapped flat again. These inserts point slihgtly down in use a few degrees - this gives the clearance required under the cutting edge.

I would not bother making a tool holder - it is cheaper to just buy a proper tool holder for them (most have carbide seats anyway). I have taken cartridges for kennametal boring bars/facemills and modified them as a toolholder - works great (cost $5 at auction, new).

08-10-2003, 07:48 PM

Aluminum is best cut with HSS and a high positive rake. Using carbide is like trying to swat a fly with a sledgehammer. Negative rake also uses about 20% to 50% more horsepower. Many jobs that used to be done with negative rake tools are now being done with positive rake against all machinist "rules". This includes hard to machine metals and work hardening metals.