What cutter for clutch friction material?

[67Charger]

I'm needing to make some replacement parts for an obsolete model of air actuated fan clutch for a piece of equipment. I'm cutting 5/16 thick non-metallic friction material and it is MURDER on standard HSS tools, even coated. Would carbide fare better? Diamond grit?

The piece is 5.75" OD, 3.5" ID, [10] .500" holes on a 5.25" pattern around the perimeter for the drive pins. The holes drill fine, but the heat from the 1/2" endmill is destroying the bits in a single pass. I've tried 2 and 4 flutes at 2000 rpm and 10 IPM, both evidently bad combos, but there are no available speed/feed specs even in the "Bible".

[Delw]

when we did brake pads and clutchs for a comparny that need to fix there machinery, we uses a square flat carbide insert with a EXTREME positive tool holder. I think it was kenmetal ( in the early 90's) the carbide insert was relieved so the tip would cut and not the bottom. we also used them on honey comb parts (made out of the same material so it would cut and not bend.

it was h13 carbide with like a .008 rad that was very sharp at the top land.
I had never seen a tool like that offered anywhere but it was a kenmetal tool I am sure, as most of our stuff came from kenmetal in those years. it was like a 30+ up degree angle on the insert.

cut great but funniest looking tool I have ever seen.
also dont forget that material is very abrasive.

[RCaffin]

Originally Posted by 67Charger 5/16 thick non-metallic friction material and it is MURDER on standard HSS tools, even coated. Would carbide fare better? Diamond grit? The piece is 5.75" OD, 3.5" ID, [10] .500" holes on a 5.25" pattern around the perimeter for the drive pins. The holes drill fine, but the heat from the 1/2" endmill is destroying the bits in a single pass. I've tried 2 and 4 flutes at 2000 rpm and 10 IPM, both evidently bad combos, but there are no available speed/feed specs even in the "Bible".

First of all, yes, it is terrible stuff. But it can be worked OK. Yes, I have done it.

You say the holes drill fine. That is probably because you are using a low surface speed and a high feed rate with the drill bits. They are seriously cutting, not rubbing. And that is the critical bit.

So ... cut mill speed right down, up feed rate, and use an aggressive coated carbide bit. Make the cutter dig in and cut.

Yes, you could go to diamond grinding, but that is much slower.

Cheers

[67Charger]

You thinking along the lines of4 tooth, 500 rpm and .005 IPT = 10 IPM???
...more bite???

[RCaffin]

Originally Posted by 67Charger You thinking along the lines of4 tooth, 500 rpm and .005 IPT = 10 IPM??? ...more bite???

When you are drilling you are probably getting more than 0.005"/turn. Start there with a pretty solid cutter - maybe 2-tooth, and see how you go.

Cheers