NEGATIVE POSITIVE Insert

Hey Folks,
Before you bother reading this know that I'm a nube to CNC Machining. I scored a fully decked out HAAS TM-P3 about 6 months ago and have been learning as fast as I can go. Please bear with me.

SO - Haas had their year end tool sale and considering the price of the haas tools and the junk tools I started with I thought it maybe a good time to score some less junky tools and I did just that. One of the things I purchased was a complete short neck 3" shell mill with inserts that state they have positive and negative rakes. The inserts are sold as "general purpose" for aluminum. I understand what a positive rake is for and what a negative rake is for but what the hell does it mean to have both a positive and a negative rake.

Here are the inserts. HAAS SQUARE SIX NEGATIVE POSITIVE (HS6NP) CONVEX TRIANGLE INSERT, 6 SIDES, ALUMINUM, N05-25, - PACK OF 10

Thank you for your time.

Generally these are a double sided insert that has a twisted shape to give a positive cutting edge with a negative mounting angle in the cutter body.
like these iscar ones
https://www.iscar.com/eCatalog/Family.aspx?fnum=2739&mapp=ML&GFSTYP=M

Obviously these haas aluminum inserts have a more exaggerated profile

Well, this is kind of a WAG, but it looks like 3 neg rake corners and 3 pos rake corners on the same insert. I’ve never seen anything like and really don’t know what the advantage would be.

Maybe someone else could chime in.

Booze Daily said:

Well, this is kind of a WAG, but it looks like 3 neg rake corners and 3 pos rake corners on the same insert. I’ve never seen anything like and really don’t know what the advantage would be.

Maybe someone else could chime in.

Click to expand...

It seems that by very clever (IMO) ''twisting'' of the insert mounting, you can get a positive cutting action from a double sided neg insert - here's the cutter body 90 DEG FACE MILL, 2.5" DIA, TRIANGULAR 6 SIDED INSERT, NEG / POS GEOMETRY

First off, the material does not care about what angle the insert sits in the pocket, it only cares about the cutting edge presented to it.

Those inserts. I'm not sure what to say. I'd really need to hold one and look at it really good to see what I think about it.

One thing I can say. Proprietary inserts, especially funky ones, tend to die a quick death, which means that the holders and face mills you buy now, may be worth scrap price in a year, and you'll be out buying new face mills and tool holders because you can't get inserts anymore.

We had pos neg cutters that were positive to the face but negative to the OD with having the insert edge set above the centerline facing the OD.
The angles were given as axial and radial.

But that was in the cutter/insert pocket placement..not the insert design.

That would suck ;(

Thanks for all the input guys. Ill be using it today on some 7075 and hopefully it works well. Im also hoping for a descent surface finish.

Thank you!

can you post a picture of the insert from the side?