End mill on fiberglass & polyester resin composite material

I am cutting fiberglass & polyester resin composite panels. Most are in the range of .090" to .125" thick, so I'll focus my question around those thicknesses.

This stuff is abrasive as heck... so I'm cutting with a PCD bit from RobbJack. .250" in diameter. I am currently cutting at 15,000 RPM with 50-60 IPM. I'm worried that my chipload is too small, and therefore prematurely wearing out my bits. That puts my chipload between .0017 and .0020. I found a chart online that says I should be between .003" and .005", ideally at the top of that range.

My problem is, I have bad suction, and cannot cut much higher than 60 IPM. So if I want to cut with the greatest chipload I can (.005"), I'm at 400 SFM, 6,112 RPM, and 61.12 IPM. Does this make sense?

I'm worried that cutting at my current .002" chipload, I'm prematurely wearing out my bit due to heat.

I am cutting a full slot. No finishing pass. One time around and it looks great on the edges.

Thanks for any help.
Jon

I think you nailed it. Biggest problem I see in the field is customers rubbing their tools to death with too low of a feed. Your logic is solid on lowering the SFM and maintaining chipload.

I do a lot of that stuff for a friend. I run 2 and 3 flute uncoated carbide mostly and have found 8000 RPM for .250 tool about right. I feed as heavily as the parts/fixturing will allow. Which sometimes isn't that much. Stuff flexes a lot.

I use longer LOC tools and vary the cutting depth to get the most out of them.

Interesting thing is that even when they are worn a thou or two they still cut fine. I will just comp diameter for awhile instead of changing tools and they run good enough for our use. Most time our parts are +/- .010" so not like that .002" extra matters.

Thanks guys - I appreciate your help. I'm glad to hear that I am on the right track.

So regarding chip load - do certain materials have certain chip loads? Does it matter what bit I use? So if I'm cutting fiberglass, no matter what bit I use, I want to aim for the .003-.005 inch chip load?