PDA

View Full Version : Insert needed for 17-4 stainless with chip breaker



ahidley
04-08-2011, 04:09 PM
I am having a hell of a time figuring out which insert I need. The problem is breaking the chips. So lets assume I have everything correct, depth of cut, feed, ridgity, lack of coolant!!! , etc. Presantly I have a set of 1/2 insert tool holders. They have TCMT32.52 inseerts in them. Thats all I know. I know that the chip breaker designation is after the number I just said. SOOOOOO Could somebody tell me the entire insert number I would need for the above listed holder to break 17-4 stainless chips? The depth of cut will be approx .015 inches. I know there are many experienced stainless guys here. I am hesitant to ask the salesman because thay dont actually use them. Thats the next/last resort if this does not pan out. Once I get a number I will patiently look on ebay for them.
Thanks.

mc_n_g
04-08-2011, 05:35 PM
Very general rule of thumb is your radius is the minimum depth of cut. Feed rate is at least half of the radius.
With stainless you have too small of a final cut with a 2 radius insert (0.032"). I do not see you breaking the chip unless you stop the feed.
You might also not be getting under the heated cut and create a work hardeneing part.

PixMan
04-08-2011, 05:55 PM
Where are you located? I might have a couple I could send you to try. BTW, in 17-4 SS, I've learned that steel turning grades with upsharp edges and tight chipbreaker designs work best.

ahidley
04-12-2011, 06:52 PM
PixMan you have email!!! Thanks.

bobw53
04-12-2011, 08:03 PM
For what it's worth, PixMan is right, Kennametal even classifies 17-4 as a "steel" not a "stainless", when it comes to choosing inserts.

It is a little more "stainless" like in the non-heat treated form, and it machines
a little worse.

Pretty much any generic steel insert should work fine for you. Treat it like a pre-hardened 4140 and every thing tends to work out pretty well.

If you aren't breaking the chip, try some more surface speed, some more feed with a smaller DOC, or less feed with a bigger DOC.

You're looking at a depth of cut of only .015, which tells me you are HP and rigidity limited, that means you might not be able to break the chip at all, regardless of insert. It happens, you just have to deal with it, and try not to cut your finger off.

PixMan
04-13-2011, 10:22 AM
E-mail replied to, ahidley.

I regret to say I found I have none of the inserts I'd hoped to have in that TCMT/TCGT geometry.

For light cuts and slower feeds on steels and martensitic/ferritic stainless steels, I've been using Valenite CCGT32.51-PM2 grade 5625. It's their middle-toughness/wear resistance steel-turning grade, and the PM2 chipbreaker is a steep 18 upsharp edge, .033" to the gullet where it then rises at 15. Rated for .020" to .140" depth-of-cut, and .003 to .013" per rev, I've been able to use it successfully in 17-4 as a finishing tool at .0024" per rev and .015" D.O.C.

I'm sure that are other grade and chipbreakers from many other makers at lower prices, but I go with what works.

ahidley
04-13-2011, 06:40 PM
Bobw53 has it exactly in his last sentence.
Pixman Thanks, I will try all advice

Signed,
lucky seven
(they are the only surviving fingers!!!)