Cutting carbon/epoxy rod

General Composites Discussions Composites Talk
#1

Hello,

New to the forum! Work in a small composite fabrication company. Presently running into some small problems when cutting small diameter rod. I have to cut 1,7 mm round rod into small sections. The problem being, at the end of the cut, when the cutting blade exits the rod it seems to burn of the epoxy there and leave a small bur in the form of some carbon fibres. You can see it in the attached picture on the top two sides of the small piece of rod shown.
The setup I currently use is a saw set up, with a 127mm cutting blade spun at 5000 rpm. I am not cutting with any coolant. What would be a possible solution for this problem? I have tried varying the feed rate, doesn’t seem to help. Maybe higher cutting speed? (tried lower, didn’t seem to matter.) Would wet cutting help? I am thinking about using a tile saw and trying to wet cut, but it would mean that the cutting speed would go down to 3000 rpm, would this still be ok?

Many thank in advance!

#2

Depends on the diameter of the sawblade…

Does anybody know the optimum cutting speed (m/s) for carbon/epoxy?

What kind of blades do you use? Diamond? Slotted?

#3

Hello,

Usea diamond coated abrasive blade. I find a lot of contradictory information on cutting speeds… Diameter of the blade is 130 mm.

#4

Another option could be to feed the rod through a tube, and catch it in another (tight fitting) tube on the other end.

#5

And keep the feed rate very low.

#6

Carbon is a pain to cut, and unidirectional always frays. Abrasive diamond blade, slow feed, and add some coolant maybe. Hard to do on some equipment, but needed. Maybe rotate the rod as you cut, so you are slowly cutting the outside first, then finish the cut on the inside.

#7

rotate the rod

#8

i cut very thin wall (sub .050") uni tubes almost daily. the god send for me was a wet tile saw with diamond grit blade. wet and slow(feed) with no tearout. if you are in production, just get one with a nice sliding bed. also eliminates dust.

rotating does work but in some applications trying to maintain a square end is harder when rotating.

#9

Thanks for the pointers! Tried adding coolant, huge improvement! The present setup doesn’t allow to use a lot of coolant thought, so probably will have to change setup. Does anybody have any experience with sawing at higher rpm’s? Thinking about an air driven sawing unit with coolant. Maybe the higher rpm wll improve the cut too?

Also looked into a tilesaw, typically these run at 3000 rpm, wouldn’t the lower speed reduce the quality of the cut? And yes, it is in a production enviroment, so looking for a solution offering good repeatablity too. (numbers running in several thousand pieces needed)

Unfortunately rotating the product isn’t possible in the process we have…

Thanks again for the advice, much appreciated!

#10

If I have to cut lots of carbon rods and tubes I use a wet-saw for cutting tile. It makes clean cuts, the water keeps things cool, and there is no dust.

#11

In addition to the high RPM, Ive found a backing structure to be the most repeatedly reliable so placing it in another tube, even locating it on some timber and cutting into the timber at the end of cut.
Also important is the tooth design on your cutter: Fine tooth size will obviously have much less chance of delaminating than a rough one.