TPG vs. TPC for indexable end mill?

[homebrewed]

I have a 1.25" R8 indexable end mill. It accepts two TPx-322 inserts, where "x" is either G or C. According to one source, the C variant has ground-in "wiping flats" and is considerably more expensive, compared to the TPG with just one radius ground at each corner.

What is the purpose of the wiping flats? Is the TPC more suitable for end mills, compared to a TPG?

I suspect the answer will greatly depend on what I'm cutting and quality of finish I want but it would be good to know what the tradeoffs are for a 4X difference in price (from one online source I use, anyway).

I'm currently working on some hot-rolled to get it to size and the indexable end mill is mostly being used to get below the mill scale so in this case the finish really isn't a factor. Thinking that a cheaper set of TPG inserts would be just fine for that....unless the flats extend the life of the cutting edge by a factor of 4 or better....

 

[MrWhoopee]

Stick with the TPG. You might get a better finish with the TPC, but I doubt any better life and certainly not 4x better.

 

[GeneT45]

I believe the difference between 'C' & 'G' is simple tolerance. 'C' is a tighter tolerance to nominal. Usually this doesn't matter for manual machines, since you'll probably cut-measure-adjust, but it can be important for CNC work.

GsT

 

[Jimsehr]

I have a 1.25" R8 indexable end mill. It accepts two TPx-322 inserts, where "x" is either G or C. According to one source, the C variant has ground-in "wiping flats" and is considerably more expensive, compared to the TPG with just one radius ground at each corner.

What is the purpose of the wiping flats? Is the TPC more suitable for end mills, compared to a TPG?

I suspect the answer will greatly depend on what I'm cutting and quality of finish I want but it would be good to know what the tradeoffs are for a 4X difference in price (from one online source I use, anyway).

I'm currently working on some hot-rolled to get it to size and the indexable end mill is mostly being used to get below the mill scale so in this case the finish really isn't a factor. Thinking that a cheaper set of TPG inserts would be just fine for that....unless the flats extend the life of the cutting edge by a factor of 4 or better....

Try tpu same insert but ground on top and bottom. Cheaper than TPG which are ground all over.

 

[homebrewed]

Try tpu same insert but ground on top and bottom. Cheaper than TPG which are ground all over.

Good idea but TPU style inserts seem to be kinda rare. Carbide Depot doesn't carry any larger than 22x versions. Shars doesn't have any in the size I need. Neither does McMaster-Carr. Scrolling through a few pages of ebay "hits" didn't reveal any, either (but I gave up after scrolling through a few pages).

Carbide Depot has a bunch of TPG322 inserts but it's not easy to figure out which ones are suitable for a particular application. The "grade description" for a product doesn't contain any ANSI specs so who knows for sure in that regard. It looks like it's just a rehash of a sales brochure.