Import Carbide insert review:

[Doc Nickel]

A couple of weeks back I asked about some import carbide inserts that ENCO had on sale. Inserts that were usually $4.95 going for $1.19, and so on.

I like deals as much as the next guy, but I tend to get leery when the price seems too good. I asked if anyone had tried 'em. Some said yea, some said nay.

Anyway, I bit the bullet and ordered four boxes; two 10-packs of TPU-322 (one in C2 grade and one C5) and two packs of CNMG; one was 431 C6 with a Tin coat (I was after the grade more than the Tin, that was just what they had) and some 432, also C6 but no Tin. (1/64" nose radius and 1/32" nose radius.)

Grand total with shipping was just a bit over $80, so they cost me right at $2 per insert.

Haven't cut anything yet, but here's my impressions so far:

The two sets of TPU came in identical boxes but with different labels, and obviously of different manufacture. The C2s are noticibly ground better (smoother/shinier) and under magnification have a noticibly sharper edge.

Pretty much the same game with the CNMG- The uncoated C6 is slightly, but definitely, made and ground better than the Tin coated ones. Under magnification, the uncoated has a fairly sharp, square corner, while the coated has a teeny, tiny, but again definite radius.

Other than all that, they seem uniform and of pretty decent quality. I couldn't beat the price, and now I have inserts that'll last me years and years at the rate I use 'em.

Once I've cut some parts, I'll have a better idea how they hold up.

Doc.

[Swamp Donkey]

I don't do much machining all in all, but what I do is almost always inturrupted cuts in hardend tool steel, so I only use carbide, and the inserts (TPG 322) don't last very long.
Buying the Pro Cut brand of cheap imports from Rex Supply I've seen a wide variation in quality. Most was pretty uniform and lasted about the same amount of time, but I got one box a while back where every single one chipped the edge on the first cut.

[Doc Nickel]

A TPG 322 strikes me as pretty small for an interrupted cut in hard steel, unless the part is itself pretty small.

When I did those transmission rings, I blew the tips off a TPG in about a half a revolution- pretty hard sintered steel, plus the interrupted cut on the "gear" teeth on the outer edge.

I beat that by bumping up to an SNMG insert- 1/2" IC rather than 3/8", 3/16" thick rather than 1/8", and since it was a zero-clearance insert, the cutting edge had better support.

Even then I smoked five of the inserts' eight points in the course of doing all five rings.

Now then, I agree with you on the variation. There's clearly three or four different manufacturers- or at least job lots- in the inserts I bought. Two look good, two don't look quite so good. And even the "good" ones don't look quite as good (cosmetically speaking) as a name-brand Kennemetal or Valenite.

I plan on buying a small supply of "real" name-brand inserts for the holders I have, just so I have some on hand for that rare high-dollar, crucial customer job. I'll save the cheapies for the jobs where I'm turning off layers of rust or mill scale, and use the name-brands for the quality work where precision is important.

Doc.