What is the purpose for carbide insert anvils?

[setlab]

I'm wanting to use some carbide threading inserts in a big inside diameter thread cleaning jig design and am wondering if I should include the anvils or not. What are their purpose mounted behind carbide inserts? From what I gather looking at catalog dimensional charts, the anvil sets the angle of attack that the inset cuts at and in the case of ID turning provides clearance to the tools trailing edge to not interfere with the cut. Is that it or do the anvils also provide support so they don't break under high loading?

 

[sfriedberg]

For threading tools, it's both. The smaller threading tools get by without anvils, mostly because there just isn't room for them.
For turning tools, the seats have parallel faces and do only the support job (and I suppose make insert location more repeatable, too). Lots of tools don't have carbide seats, especially mill tools.

 

[Joe Gwinn]

... Is that it or do the anvils also provide support so they don't break under high loading?

Yes. The reason is that carbide is far stiffer than steel, so one needs the anvil to spread and transfer the cutting forces to the steel bit holder bar, without squishing any steel out from under the carbide bit.

 

[CarbideBob]

Yes. The reason is that carbide is far stiffer than steel, so one needs the anvil to spread and transfer the cutting forces to the steel bit holder bar, without squishing any steel out from under the carbide bit.

Wrong... This has a small amount of true for seats but they are there to protect the holder from crash/broken tools.

In threading the flank angle changes with pitch. The thread is moving forward and the insert flank or front side needs the right clearance.
The front side comes at your leading edge faster per rev so one needs to twist the insert to comp for that and hold heel clear.
So one it is how fast you need to feed per rev that needs the help using a standard insert. Ideally the insert would be ground to each thread pitch but that only done in high volume users.
(does any of this make sense?)
Bob

 

[Joe Gwinn]

Wrong... This has a small amount of true for seats but they are there to protect the holder from crash/broken tools.

Hmm. I recall the stiffer-than-steel explanation from such as Iscar, though a carbide seat will also help during a crash et cet. Both statements could be true.

In threading the flank angle changes with pitch. The thread is moving forward and the insert flank or front side needs the right clearance.
The front side comes at your leading edge faster per rev so one needs to twist the insert to comp for that and hold heel clear.
So one it is how fast you need to feed per rev that needs the help using a standard insert. Ideally the insert would be ground to each thread pitch but that only done in high volume users.
(does any of this make sense?)

Yes, it does. Some threading tools have an adjustemet for exactly this purpose. Needed only for steep and/or coarse threads.

 

[Mark Rand]

One problem I've found with my threading tools is that there doesn't seem to be a standard for the anvils like there is for the inserts. So I hadn't been able to work out if any of the anvils available would fit my (no-name) tools when I needed to turn a 7/16" 10tpi left-hand ACME thread. I ended up grinding spacers to go under and over the tool holder to change its angle.