Thread: Parting Insert Tip Problems

The only thing I have seen like this is my cheap Chinese inserts used in the 9 piece sets. I have cracked them just putting a new one in they are so brittle, but luckily they are only 25 a pack of 9. Though I have not had a problem with the parting ones at all, so your problem sounds strange.

Dave

Lee,
That type of fracture indicates that the insert lacks the necessary toughness for the job.
What suffix was indicated for the grade eg P20?
Coated Part Off inserts for general steel cutting applications are usually classified as P20, giving a good toughness characteristic with the wear resistance coming from the coating.

It could be:
1. A K type straight tungsten/cobalt carbide. Possibly K10 used for Brass, Aluminium and Cast Iron.Which has high wear resistance and lower toughness.
2. Inserts that have been incorrectly Sintered , that is overcooked but as that is an Iscar designation it should be a rarity ( but fairly usual in some Chinese cemented carbides.
3. They used the wrong powders in the process.

Col

Dave and Col, tks for your input................

Col, they are TiN coated C-5 Grade which covers stainless as well as all steels (so they claim!).

The trouble with purchasing from bulk retailers, is that unless you know the brand or they provide the code under which they are manufactured, it's impossible to know who made them and to what code

These were purchased from Shars, they advertised them as "general purpose for cutting all steel and stainless".............these had no brands so you take in good faith what the seller claims them to be....knowing full well they didn't make them.

I'll just put these down to experience I think and return to my normal Vandurit/Iscar inserts at 4 times the price ................I was more concerned that I may have been doing something wrong, but going back over what happened - more inclined to think Point 2 above is what the problem is....and certainly not my machining........couldn't possibly be!!!......could it??.

Tks for your suggestions.......Lee

Lee what were you parting?

Yes I have seen this type of failure, just recently in fact when turning some stainless. They were conventional inserts but the failure looked identical. I think Col is spot on with his description of the issue.

Pete

Pete, was cutting 5/8" cold rolled MS rod which I had turned down to 3/8 BSW threads and was parting to length......I've had no issues in any parting with other tips.....just these and that's why I'm thinking along Col's post....makes sense.........

Did some close inspection to make sure it was square as to me it looks like they are mostly fracturing on the one side - unfortunately most of them I couldn't find!! ...lots of things go through your mind like, not square to the work, blade bent, feed/speed, approach angle etc...anyway, went through everything I could think of and couldn't see any reason other than most likely they are faulty......unfortunately I didn't have any other tips for a comparro at the moment - but have ordered some different ones from another supplier so will wait and see....guess the original post was to see if anyone else had experienced similar..........now crossed these ones off the list for trying to save some dollars............Lee

Yes when you said you swapped out to HSS I guessed it couldn't have been anything too exotic! I just use a crappy HSS blade for parting but have been looking at these "fancy" insert parting tools. Your story makes me wonder whether they're really a good substitute for a sharp HSS tool, though I've heard many people absolutely swear by them.

Let us know how you get on with the replacement inserts.

Pete