Carbide Inserts?

[terry_g]

I found these in a cabinet in a shop that had a lathe and a milling machine although the milling machine was gone when I hired on. This was over 40 years ago and they could be a lot older. They are .375" square and .130" thick and I think they are tungsten carbide. Some are marked K21 on both side and some are marked Coromant S4 on one side and SQT 122 U2 on the other.
Does anyone here have any idea what they would be used for?

 

[mbond]

too bad - the only think i can think of is clamps. But thats not so good as screws

 

[Proxule]

Braze it on some mild steel and whala, 45 degree chamfer tool!

 

[ducdon]

Braze it on some mild steel and whala, 45 degree chamfer tool!

I totally agree. Braze to a shank and grind to whatever shape you need.

 

[Susquatch]

At 3/8 square, they might be pre-insert-era cutting tool blanks meant to be brazed on and then shaped?

 

[Ironman]

A lot of toolholders have a carbide pad under the insert which looks like that

 

[Susquatch]

A lot of toolholders have a carbide pad under the insert which looks like that

I thought all of those had a hole in them.

 

[Tom Kitta]

"K21 is a C-2 /C-5 hybrid, lots of TaC for thermal cracking, this makes it kind of soft but it likes heat"

You can either braze them on or use a tool holder that does not need a hole. They look to have no angle to them i.e. angle is zero or letter N. So you have 8 edges.

I do not think these are insert pads - I think these are old inserts. Just test one out and see how it does.