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Insert seat damage when turning copper

Ju1ien

Plastic
Joined
Jan 7, 2016
Hi guys,

I am looking for some suggestions with a recurring issue we have when turning copper, which we do a lot of.
On occasion, when someone does an insert change, the dimension will jump or drop by an exaggerated amount like .008 or so.
When I go out and look at the insert seat, sure enough the insert shifts back and forth slightly which is causing the change.

I suspect that the chips jam up on the tool every so often and the sudden impact is making the insert push back into the seat and causing damage, and when the insert is changed it doesn't seat the way it was before. This can occur on both the Z and X direction of the seat, but typically happens in the Z direction. The bottom of the insert seat is fine, it's the sides that are impacted.

We are using standard 1" x 1" square shank Kennametal CCGT holders (SCLCR 163) and they all seem to succumb to the same problem over time.
Does anyone have any suggestions on a turning tool with reinforced seats? Some other solution?

Thanks
Julien
 
and when the insert is changed it doesn't seat the way it was before.
Has the tool been smashed or has the tool had an insert bust while cutting and damaged the seat area?
Take a small needle file and/or stone and go over the seat area to make sure there isn't any raised edges causing this to happen.
 
Orange - the carbide shim is located on the bottom of the insert. The sides of the insert seat are the impacted area. As far as a top clamp style insert - we have some programs that use these but they're never as effective as our Arno / Mits inserts for our applications.

Mtndew - No busted inserts, just lots and lots of chips jamming up over time (massive pecking cycles). No raised edges, just impacted steel and the ability to wiggle the insert back and forth slightly.
 
Got any pictures of the damage?

The fact that the dimension jumps in both directions is odd to me, I feel like if the insert was getting pushed back in the seat, and the operator was making offsets in X- to compensate for the now shorter tool, then when they put a new insert in, it would sit against the damaged seat and stay at the same dimension, or no?
 
Got any pictures of the damage?

The fact that the dimension jumps in both directions is odd to me, I feel like if the insert was getting pushed back in the seat, and the operator was making offsets in X- to compensate for the now shorter tool, then when they put a new insert in, it would sit against the damaged seat and stay at the same dimension, or no?

Yeah I'll get a picture up soon. Sorry if I wasn't clear - the dimension may or may not jump, just depends how the operator puts the insert in and tightens it. When you put an insert into the damaged holder, you can actually wiggle the insert back and forth every so slightly in the seat. If you tighten it down with force then it typically wont move. It's an annoying repeatability issue that causes us to scrap copper
 
Yeah I'll get a picture up soon. Sorry if I wasn't clear - the dimension may or may not jump, just depends how the operator puts the insert in and tightens it. When you put an insert into the damaged holder, you can actually wiggle the insert back and forth every so slightly in the seat. If you tighten it down with force then it typically wont move. It's an annoying repeatability issue that causes us to scrap copper

Tooling is consumable... I assume you have tool life on the inserts... Can you not just set tool life on the holder too?
 
Are you sure you are not putting 11 degree inserts in a 7 degree holder? It's a common mistake because the inserts look so similar with those small 80 degree inserts. A CCGT insert has a 7 degree relief angle. CPGH inserts are 11 degree and yes you can put a CPGH insert in a holder made for CCGT inserts. Just something to check.
 
Tool life on the insert is much more predictable than the tool life of the holder itself, but that is basically what we do. I chuck them in the trash when I see the insert is wiggling. I don't care so much about buying holders I just want a way to prevent copper scrap.
Here is a picture of an old one I kept. Not sure if you can really see the "damage" to the back of the insert seat, but it's there. The insert can move back and forth even when tightened down.

20240523_103201.jpg
 
Switch to an MCLNR holder that uses CNMG negative inserts. They all have carbide shims. Then use an insert with high positive geometry similar to your CCGT inserts.

This seems a good solution. The way the inserr fits in the pocket is more durable, and lots of negative-positive inserts are available.

BTW, the part that is wearing is the pocket, not the seat.
 
This seems a good solution. The way the inserr fits in the pocket is more durable, and lots of negative-positive inserts are available.

BTW, the part that is wearing is the pocket, not the seat.

My bad! Yes, the pocket. And I am looking into the MCLNR inserts now, thanks!
 
Tool life on the insert is much more predictable than the tool life of the holder itself, but that is basically what we do. I chuck them in the trash when I see the insert is wiggling. I don't care so much about buying holders I just want a way to prevent copper scrap.
Here is a picture of an old one I kept. Not sure if you can really see the "damage" to the back of the insert seat, but it's there. The insert can move back and forth even when tightened down.

This a picture of the actual insert and holder in use?
If so .. many things wrong.
 
Missing is the shim seat, threaded inside and out shim screw and correct insert screw.
Insert cutting edge should always be above the pocket wall.
Here is worse if used like this even if you shimmed for C/L height since the locating wall is for a negative shim seat.
This holder number comes in two flavors. With and without shim seat depending on made by who and year.
Maybe the picture is without the insert mounted so as to see the insert pocket walls?
Strange to see a positive rake shim seat but it carries a number I do not know or have prints on. (SKCP-343)

Insert callout being used? "G" or "M" in the third letter?
 
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