Machining of GFRP

General Composites Discussions Composites Talk
#1

Hi everyone,

I have just joined this very informative forum :slight_smile:

I need to machine test specimen to do some ISO tests (tensile/compressive/flexural, etc), which are made of an ortophtalic polyester resin, reinforced with e-glass fibres, mostly CSM and Woven roving. Thickness ranges from 2.5mm up to 6mm.The fibre content by mass is about 30 to 40%. Would a conventional CNC machine (we have Bridgeport manual and a Cincinnati CNC) do the job, or would these damage the slides and equipment?

Thank you for your help!
Regards
Jeremy

#2

coolant/water cooled diamond tools are the best. If you can machine with a fine diamond bit on the CNC, or a diamond coated wet saw, it would be best. Waterjet cutting is also effective if you can.
We use diamond wetsaws for most of our test samples. A slot grinder that takes off 1mm at a time makes a nice finish. Just takes awhile.

#3

Thanks a lot for that, very helpful :slight_smile:

Would a carbide endmill to the job, on a manual milling machine?

#4

i’d get a diamond coated, solid carbide end mill at very least. that’s what i use (with flood coolant) on all the carbon parts I cut, and the end mill is still running strong…not that i cut carbon parts all the time though.

#5

Careful when using end mills they can cause delamination by pulling the layers of material in only one direction. A Compression router bit is what should be used when trimming on a cnc mill. A 5 axis water jet also works well but arn’t exactly available in all areas… Here is a good article how Lockheed has switched to Compression router bits for the F-35 due to delamination issues, and it also talks about the available coatings for tools so they can last in the advanced composites world.
http://customcarbidetools.com/tool-type-and-geometries/the-composite-cutting-tool-challenge/
Then here is another good article about the F-35 program.
http://www.mmsonline.com/articles/composites-machining-for-the-f-35

[ame=“http://www.youtube.com/watch?v=__hbDhZxsaY”]Compression-Style Router - YouTube[/ame]

#6

very good to know!

#7

I am going for a diamond wetsaw, like the one below:

http://www.amazon.com/exec/obidos/ASIN/B00005A1J5/floorstransforme

I hope it would do the job! Thanks for the advice :slight_smile:

#8

Thank you all. I am buying a wet saw and hoping it would do the job!! :slight_smile:

http://www.amazon.com/exec/obidos/ASIN/B00005A1J5/floorstransforme