Carbide inserts tolerance

[kmanuele]

I read a post (sorry, can't remember where) which suggested trying some 'G' tolerance inserts, as in CCGT, instead of typical CCMT. Stated that the insert is honed to dimension and has sharper edges as a result - finer finish and/or low DOCs.

So, I ordered some CCGTs from Kennametal, and found that the edges were quite sharp. Not quite as sharp as an aluminum insert, but close. Worked quite well on 1045, compared to CCMT.

Not sure that tight tolerance automatically means sharp edges and maybe it was the Kennametal brand, but has anyone seen this effect on 'G' tolerance inserts?

thx

K

 

[MyLilMule]

Someone told me it was the cutting radius, but I understand that not to be correct.

M = .08mm radius
G = .04mm radius

In any case, I have some CCGT inserts as well. I've only used them a couple of times, and so far so good. I would imagine they won't hold up as well.

Insert Designation Chart - provides ANSI and ISO designation code definitions for carbide insert shapes, relief angles, tolerances, chipbreaker codes, hole types, size values, thickness values, radius values, wiper lead angle, wiper clearance angle,

Carbide Insert Designation Chart

www.carbidedepot.com

 

[mattthemuppet2]

The nose radius is the number after the decimal for SAE (**.*1 eg 32.51) and the two size numbers for metric (**04 eg 0904).

The G is a tighter tolerance on size vs M, which usually means ground vs just pressed, but doesn't have to be for the big name brands. It's simply that grinding is an easier way to get the tolerance

 

[davidpbest]

I read a post (sorry, can't remember where) which suggested trying some 'G' tolerance inserts, as in CCGT, instead of typical CCMT. Stated that the insert is honed to dimension and has sharper edges as a result - finer finish and/or low DOCs.

So, I ordered some CCGTs from Kennametal, and found that the edges were quite sharp. Not quite as sharp as an aluminum insert, but close. Worked quite well on 1045, compared to CCMT.

Not sure that tight tolerance automatically means sharp edges and maybe it was the Kennametal brand, but has anyone seen this effect on 'G' tolerance inserts?

thx

K

A CCGT insert has a much tighter dimensional tolerance than a CCMT insert, and to attain that tighter tolerance, the CCGT is typically honed or ground to size after sintering (the process of fusing the carbide, cobalt, etc mixture under heat and pressure). A CCMT is is not typically honed or ground after sintering and thus will almost certainly have a molded cutting edge. But that doesn't mean that all CCGT inserts have a razor sharp edge. The insert "Grade" and chip breaker specification will further define the actual edge sharpness.

I don't know the specific grade of insert you bought from Kennametal, but they make several CCGT insert grades, each having particular properties typically matched to the type of material and operation (roughing, finishing, etc.). A CCGT graded for use on steel will certainly have a sharper cutting edge than a CCMT of the same grade, but that doesn't mean a CCGT that's graded for steel will have the same cutting edge geometry of a CCGT graded for use with aluminum. Along the same lines, a CCGT graded for use with aluminum will certainly cut mild steel and most stainless materials, but it won't last nearly as long as a CCGT insert graded specifically for steel or stainless.

 

[kmanuele]

A CCGT insert has a much tighter dimensional tolerance than a CCMT insert, and to attain that tighter tolerance, the CCGT is typically honed or ground to size after sintering (the process of fusing the carbide, cobalt, etc mixture under heat and pressure). A CCMT is is not typically honed or ground after sintering and thus will almost certainly have a molded cutting edge. But that doesn't mean that all CCGT inserts have a razor sharp edge. The insert "Grade" and chip breaker specification will further define the actual edge sharpness.

I don't know the specific grade of insert you bought from Kennametal, but they make several CCGT insert grades, each having particular properties typically matched to the type of material and operation (roughing, finishing, etc.). A CCGT graded for use on steel will certainly have a sharper cutting edge than a CCMT of the same grade, but that doesn't mean a CCGT that's graded for steel will have the same cutting edge geometry of a CCGT graded for use with aluminum. Along the same lines, a CCGT graded for use with aluminum will certainly cut mild steel and most stainless materials, but it won't last nearly as long as a CCGT insert graded specifically for steel or stainless.

It was a CCGT32505LF KCU10 0.008" corner radius. For multiple materials including steel. The edges are definitely ground or honed. My calibrated fingernail says they're sharp . Looks like a basic 'C' insert, just with sharper edges. Not shaped like an aluminum insert, with those high positive rake edges.


I've tested aluminum inserts on mild steel. Worked well until edge failure -- probably my fault, but they do look fragile.

 

[davidpbest]

At this link, you can enter all the variables to find a suitable CCGT insert from Kennametal - Just use the pull-downs filters in the box on the left.

ISO Carbide Inserts - Screw-On Inserts

CCGT-HP - 100001913

tinyurl.com

Your KCU10 grade insert is indeed optimized for use on steel, stainless, and high strength alloys:

ISO Carbide Inserts - Screw-On Inserts

CCGT-HP - 4045141

www.kennametal.com