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PCD & CBN Inserts!!

thestelster

thestelster

Ultra Member
Premium Member
A guy was selling a whole bunch of inserts that he got from an auction. I picked up a whole bunch of laydown threading inserts, UN60, M60, UNJ, Acme, and buttress. Also some CCMT, DCMT. The packs were all mixed in several cardboard boxes, so it took a while to go through them. A lot of the inserts in there were really old stock, or stuff that I don't have tooling for. But I found a few gems.

PCD inserts, Polycrystalline Diamond inserts, for aluminum.

CBN inserts, Cubic Boron Nitride, for machining hardened steel (60-65HRC)

Also a 6mm solid carbide boring bar with carbide inserts at the front. You can get threading, boring, back boring, grooving heads.
 

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I bought a TNMG CBN insert figured I'd give it try. I have a chrome hydraulic cylinder rod that I'm going to use for a project (haven't yet). When I ordered I thought it was a box 10 well to my surprise it's was only for1 insert @ $12.59 delivered. A little pricey. We'll see how well it works.
 
Aliva said:
I bought a TNMG CBN insert figured I'd give it try. I have a chrome hydraulic cylinder rod that I'm going to use for a project (haven't yet). When I ordered I thought it was a box 10 well to my surprise it's was only for1 insert @ $12.59 delivered. A little pricey. We'll see how well it works.
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Usually, those CBN inserts from Sandvik or Kennametal are $130.00 each for single sided inserts, and $230.00 each for double sided inserts. And minimum order of 5.
 
thestelster said:
Usually, those CBN inserts from Sandvik or Kennametal are $130.00 each for single sided inserts, and $230.00 each for double sided inserts. And minimum order of 5.
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Well in light of that I guess I got deal. By the way the insert is double sided so a total of 6 edges.
 
thestelster said:
Hey Tom, what was your experience with the ceramics? What material were you cutting?
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I feel its around as big (or bigger) of a step as going from HSS to Carbide --- i.e. you need to think ... different. Chipping is an issue - also inserts feel dull and not sharp. It feels like all carbide properties are x3 from HSS perspective, you can cut much faster, chip much easier & its less of a cutting off and more maybe of "ripping off".

It was a while since I did this - I should try one of my indexable EM - it takes 3x round inserts. all of them are heavily chipped by previous owner - I guess we all have similar learning curve.

I usually cut alloy steel - so stuff like 4140 and 4330V.

Especially the 4330V is tough to work with in a home shop.
 
Tom Kitta said:
I feel its around as big (or bigger) of a step as going from HSS to Carbide --- i.e. you need to think ... different. Chipping is an issue - also inserts feel dull and not sharp. It feels like all carbide properties are x3 from HSS perspective, you can cut much faster, chip much easier & its less of a cutting off and more maybe of "ripping off".

It was a while since I did this - I should try one of my indexable EM - it takes 3x round inserts. all of them are heavily chipped by previous owner - I guess we all have similar learning curve.

I usually cut alloy steel - so stuff like 4140 and 4330V.

Especially the 4330V is tough to work with in a home shop.
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You have me intrigued about ceramics. But looking at one of my catalogs, it says ceramics are best suited to to cast iron, heat resistant alloys, hardened steel. And the speeds are 3-4x that of normal carbide inserts. Though, I can't get up to those speeds with what I have unless turning large diameter stuff.

Could the chipping have been caused by cutting normal unhardened steel?
 
thestelster said:
You have me intrigued about ceramics. But looking at one of my catalogs, it says ceramics are best suited to to cast iron, heat resistant alloys, hardened steel. And the speeds are 3-4x that of normal carbide inserts. Though, I can't get up to those speeds with what I have unless turning large diameter stuff.

Could the chipping have been caused by cutting normal unhardened steel?
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I think using it so rarely means people don't know (including myself) how it should be used & do not have a feel for it. Its probably like carbide in 1950s.

It is supposedly tearing material off at very high speed with material to be cut very hot. I.e. everything turns RED or even YELLOW (!!!).

I think chipping is same as with carbide but to the extreme - i.e. running it too slow. I also have a feeling that these inserts hate any interrupted cut 3x more than carbide.

So I guess I should get 1" indexable EM and run it at something like 2000 rpm in 4330 and film the results. I only used the stuff on a lathe so far.
 
Tom Kitta said:
I think using it so rarely means people don't know (including myself) how it should be used & do not have a feel for it. Its probably like carbide in 1950s.

It is supposedly tearing material off at very high speed with material to be cut very hot. I.e. everything turns RED or even YELLOW (!!!).

I think chipping is same as with carbide but to the extreme - i.e. running it too slow. I also have a feeling that these inserts hate any interrupted cut 3x more than carbide.

So I guess I should get 1" indexable EM and run it at something like 2000 rpm in 4330 and film the results. I only used the stuff on a lathe so far.
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Yeah, for sure video that! When you have the chance.
 
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