Laser cut carbon fiber?
 

Hi guys,

I'm currently working on a little project with Carbon Fiber that will require some custom cuts (a chassis to be specific) and the only 'CNC machine' I may have access to, is a 120 watt laser.

I would like to know your person experiences with this method of cutting... The pros and cons. The Carbon is 4.3mm think and they are quite a few detailed cuts for upper and lower plates.

Any help will be appreciated

Alien

Lazer cuts tend to be more precise due to the smaller cutting 'tool' diameter, though what thickness you can do is another question. I would suggest doing some test cuts of various intricate shapes on a scrap piece of material to see if it leaves a clean finish/edge like you desire. One thought is that the heat of the lazer will either leave a nice clean edge that seels itself, so is less prone to splintering, or it may leave a slightly singed edge- only one way to find out, unless there are websites that offer the same service so could advice you on what to expect.

Hey Neil, thanks for the suggestions man... I will get some tests done to see how the Carbon reacts to the laser.

Alien

hey dude,
DONT USE LAZER TO CUT CARBON. i have been building some custom carbon chassis over the past few months and i initially tried laser to cut them out as it was going to save me money. the cuts were straight and everything but what happens is the laser melted the epoxy ever so slightly along every cut made. this caused the fabric to be frayed really bad along every cut and the the part looked like shit. also, the frayed fabric gets in your skin like fiberglass and is horrible to try to work with after that.

i just use a CNC shop to cut all my carbon now and it is 10x better. save yourself the trouble. idk, i have heard of people using laser to cut carbon successfully so i dont know if the piece i had cut was inferior or what but since then i have used the same carbon cut on the CNC for my 1/8 brushless truggies and have been racing with them for weeks without any issues. and this is only 3mm carbon so i would say it is decent carbon to hold up to the abuse i have given it.

pm me if you have any other questions. i have been working with custom carbon stuff for the past 6 months and can maybe help you out with any more questions.

Has anyone thought about waterjet?

Hey Ryu, Thanks for sharing your experience man, I'll have to go search for someone here in Jamaica with the appropriate CNC machine to get this done right then...
The same company with the laser might have one. The other problem is, if I do find them, it's hard to convince the shop to try a material outside of the list they may already used for their business.

Hi Lutach, no waterjets here so far:oops:... So that's not an option for me right now.


Alien

Ok, all I know about carbon fiber and high heat is that carbon fiber burn pretty good. I've heard of people using a CNC machine and placing the CF under some sort of liquid to avoid all the harmful dust. If the same can be used with the laser then it might work.

i started out using a dremel tool with carbide tungsten bits to make my own carbon parts. then i found a CNC shop to do stuff. just make sure they use carbide tungsten bits. all other bits melt. also, the dust is extremely harmfil to breathe so you need to wear a mask when doing work with carbon. and i think it is better to run the bit at the slowest speed possible that still cuts efficiently. going faster only melts the bits or the carbon. i have found a slow speed cuts much better.

as for waterjets i havent tried it but i have heard that it also frays the carbon resulting in a very ugly part and one that most likely cant be used.

CNC is the way to go but may require some experimentation on your part.

there are some CNC shops that work with carbon all the time and really have a good system down of how to do it best. i have yet to find one locally but look around as i know there are shops that specialize in working with carbon and have already gone thru the trial and error.

Thanks for all the help guys... Here's a little preview of what I am working on.


http://lh4.ggpht.com/_4vPm5E8J5HA/Sf...0/DSC_8702.jpg

http://lh5.ggpht.com/_4vPm5E8J5HA/Sf...0/DSC_8703.jpg

http://lh3.ggpht.com/_4vPm5E8J5HA/Sf...0/DSC_8704.jpg

http://lh5.ggpht.com/_4vPm5E8J5HA/Sf...0/DSC_8705.jpg

Alien

That is a very pretty maxx.

Very nice deisgn indeed- FLM meets GorillaMaxx. Have you seen Serum's customized FLM chassis, has a similar bottom plate design attached to the FLM braces.

Thanks BL_RVO... I can't wait to see it in carbon.:yipi:

Hey Neil, I did see Serum's chassis, it was actually one of the four trucks I used for inspiration.... Here are the others:

http://i228.photobucket.com/albums/e...ntruth/top.jpg

http://www.unlimitedengineering.com/...6/DSC00532.JPG

http://www.unlimitedengineering.com/...is2_375204.JPG


Alien

Update time.. The laser ( http://www.engravingsolutions.com/ext.html ) did not work so well. :no: It started etching into the carbon,
but at the same time the epxoy melted causing the fabric to be fray:whip: (same thing Ryu James experienced).

So, for now, I'm going to be using 3/16 Lexan to build the chassis hoping it will hold up until I find another option for cutting the carbon here.

Thanks for you help guys

Alien

There must be a place there that has a CNC machine or a water jet machine.

The shop that made the test for me does have a CNC, but it's not easy convincing them to make the cut because of the dangers with the dust and the fact they don't have the appropriate cutting tool. :whip:
I explained to them it could work if the carbon is wet and there is a vacuum source pulling the dust away.

Where Water Jets are concerned, they are none. I will find a way to cut the carbon soon... Just not by who or when.:neutral:

Alien

I don't know where, or who, but you could have it punched out. It would not fray the edges if the die were made to very tight tolerances, and it would be fast once the die was made such that you could have quite a few punched out and possibly make a few bucks. :wink: :wink: :yes:

:yes:Yes, that's an idea I could look into... I do know a few print houses that employ die makers. I'll get on the phone tomorrow.

Thanks Man.

Alien

:surprised: Hey, no problem!

DO NOT USE A WATERJET!!!!

I actually posted a thread some time back with sample pics of very clean cuts on CF by a waterjet. I have completely changed my opinion. I got lots of delaminating at the corners when they actually cut my chassis, and am out nearly $100 in material.

I don't have any experience with laser on CF, but it seems to me I remember reading that it doesn't work well. At least do a trial cut, and be prepared that it may do worse on the final cut than the sample.

I have quite a few years in amateur CF, including laying-up custom bent pieces. The BEST way to cut it accurately on a budget is to use a router table. Yes, a woodworking router table. Get a fiberglass router bit (available from online tool stores if not local) and cut away with your fence guides. Be sure to be wearing a mask and have the vacuum running! If you are having internal cut-outs (as your drawing shows), you can make yourself a pattern first from wood. Mount a pin the same diameter as your bit immediately above your bit in a v-notched piece of wood secured by clamps or the like to the table, and drill a pilot hole in the CF, and run the pattern using the pin against the wood as a guide. This will work just as well as a pattern-cutting router bit (which for some reason aren't available in the fiberglass variety) does on wood.

Otherwise, full cnc is the way to go.

Here's the earlier thread I mentioned: http://www.rc-monster.com/forum/showthread.php?t=17697

I also use a router-table & router, drill-press with 3-axis milling vice, my trusty Dremel, some stationary grinders & sanders, and a couple files...you can get very professional results if you take your time.

I am buying a CNC Masters CNC Jr. ($5,000), or maybe the CNC Baron ($7,500), so that I can start manufacturing custom Carbon-Fiber, ALuminum, Titanium, Delrin, & Nylon parts for RC, 1:1 vehicles, and other things as well...I can't wait to get started!

Wow, I'm learning every day... To be honest a friend who I fly models with, told me something similar before (he's a mechanical engineer). He said because of the velocity and force of the water jet, it may be possible to delaminate the carbon.

The router option sounds like another cool idea. Do you have any photos of your setup? I am still hopeful one of the CNC owners will accommodate me and help out with the cut.

Alien

Did the place that cut your chassis use just water or did they use any abrasive material? Here is a video that shows a nice piece of CF being cut using a water jet: http://www.youtube.com/watch?v=zI4QnWOwAys.

I do agree that cnc is the way to go.

An option for you - use the laser but with a 3mm gap around the whole chassis and then sand in the rest.

For the holes just burn a tiny guide hole and then drill it out...

:yes:Yep, CNC is looking like the 'easier' way to get this done right. I also like the router option too... I really want to get this chassis done... It's my first real 'design'.

An idea, but the heat made the fibers/epoxy flash area so big (even with a mask), the frayed fibers were longer than 5mm.:whip:

Yes they used an abrasive slurry. It would be better without on the CF, but it is rare to find a shop that will jet a piece anymore without the slurry.

I don't have any pics since I haven't had it set up for the last couple years. If you're really brave (and steady handed) you can just use the fiberglass router bit in a router or even Dremel freehand.

Cool... I'll make an attempt with a small part first when I get some time.


Alien

I understand Laser/CNC are the options being discussed but I can add a little to water cutting problems

Watercutting CF will work BUT and it's a big but...delamination will occur at the point of entry (first cut) & can be up to a diameter of 20-30mm - no good for holes! and the operator should have a map & enough material to cut into the final shape from 30mm plus of the final cut

Watercutting CF can be improved by sandwiching the CF between alloy plate, this may be advantageous if you want alloy bits the same?? adds some cost though

CNC is best but destroys most tools & again the operator needs a good understanding of CF to get the best outcome

Wow, 4.3 mm carbon, are you sure you need that? Quasi-isotropic carbon has about the same stiffness as aluminium, with 40% weight reduction. I would use 2 mm or 3 mm carbon and make less cut-outs. Of course you need some for servos etc., but the others don't do much for weight saving and might hurt stiffness a lot (if you haven't done FEM on them).

Laser cutting of carbon: Yes, it does work, but you need the right machine and the right settings. Of course it doesn't work with a 120 W engraving laser, you want something in the kW range to evaporate the material instead of slowly melting it. A big problem might be emissions, which can pollute the mirrors (which results in overheating) or contaminate the environment.

Water jet cutting of carbon: Yes, it does work. We have cut 10 mm solid carbon and 5 mm sandwich consisting of 3 mm wood core and 1 mm carbon coverings. Last year, the parts were done in wet lay-up and showed minor delamination after cutting. This year, prepreg material was used with autoclave curing and the cuts are very neat.

Machining of carbon: Yes, it does work, and again, you need the right tools and settings. Carbide tools are not suitable for this, as they're very brittle. The best tools for carbon are CBN, but expensive as well. Steel tools are not suitable because carbon diffuses into the tool, changing the chemical composition.
For drilling holes, HSS tools don't last long, but are cheap. HSCO works last longer, but are more expensive.
For straight cuts, a diamond equipped circular saw is working well.

If you get a lot of fraying, I'd say you're not using the right machine or settings.

For any RC project with small quantities and a budget, I would recommend using a dremel with the cheap cutting blades and some cylindrical sandpaper grinders.

That's all off the top of my head, but it should be correct.

Regards,
Thomas