Need Help!- Would Like Suggests for Machining G-10

[burroughs]

Hi,
I'm planning for a good-sized job out of G-10 (actually it's G-11) and I would really like to hear what has for worked for folks and what has not.

I'll be running with coolant on my VMC. Am planning on mostly using 2 flute carbide. I'm wondering: Are coated tools preferable? Should I run my Rpm's on the slow side (push the feed)?

I've worked with the stuff before and understand it's nature but I want to be able to plan on tooling and don't want to go broke getting a good looking part.

Any shared experience would be great! Thanks

[Boots]

I had a project to do with G-10 1/2 in. thick and I started with 3/8 carbide and the stuff just laughed at that tool and destroyed it with in 3 in. of travel. I tried 1/4 and 3/16 but got same results. I had to go to a diamond coated bit Onsrud #67-254 @ $110.00. It's a 1/4 in. 3 flute downshear with diamonds all over it with some room for chip removal. It works great @4,000 RPM @ 20 ipm without coolant. My Router does not use coolant so you might be able to run it faster. My concern was heat and it do get hot. So you might have better luck there. As far as drilling I used HSS drills and compressed air to cool the drill bit. It produces a nasty powder that you won't want to breath so coolant will help there too keeping the dust down but it might contaminate your coolant and be undesireable. You can decide there. But that bit is GREAT for doing the cutting.

[Caprirs]

The tools (even coated) will dull quickly but continue to cut just fine. If the part has tight dimensions, you'll need to check often for tool wear and either make adjustments or change tools. However, even dull tools will cut it pretty easily.

I've worked with G10 & G11 a bunch. Flood coolant will keep the tools cool by flushing away the powder/dust. Drills tend to pack up the flutes so peck drilling is recommended.

The finish tends to be rough because the tools cut the epoxy but "snap" the glass fibers. Some light scotchbrite or sandpaper will leave a nice finish.

Depending on your coolant setup, the powder/dust can accumulate in the sump and clog screens. The glass is very abrasive and can damage the seals in the coolant pump.

[Gary55Ford]

I cut alot of G-10 at work with 1/16 to 1/2 inch 2 flute carbide end mills and use whats called a cool gun. It uses compressed air and it seperates the cold air from the hot. It takes compressed air almost down to freezing, and I get vary good use out of my end mills

[dertsap]

i'm with Caprirs



the stuff is brutal on the coolant system , plan to spend a few hrs or more draining the tanks and flushing the system clean , the stuff gets everywhere ,and takes a lot to get it all out of the machine , ive worked with loads of the stuff , it is nasty everywhich way , i hate it !
you'll know your cutter is too dull when you see some delamination (watch for light spots) , you need to keep a decent feed rate but at the same time keep the speeds relatively low or you'll burn the cutter out prematurely , it is very abrasive material no matter how you look at it

i wouldn t machine g11 on a machine i liked !

it is by no means healthy stuff to be breathing in so i would suggest some type of ventilation and plan to get vert itchy if your working with large amounts of it

[burroughs]

Hey, thanks for the suggestions. I get itchy just reading about the stuff. haha I probably should try out a couple of workhorse diamond tools but with different features and some length of cut requirements I will still be relying heavily on a variety of different carbide endmills for finishing.

I hope folks continue to reply to this. And I also will add what worked for me with the G- 11.

[Caprirs]

See attached for a fixture I made for a customer. The base and the center blocks are G11. It is a fixture for curing parts in an oven.

Their old one was made of wood and would smoke.

[Multi-DNC_user]

I first machined G10 over this past Christmas. It was a beast of a part and I had to use a lot of different tools to accomplish the job. I used Diamond coated endmills and Diamond Coated face mills to rough the material down, then came behind those with 4-flute standard carbide endmills for finishing. I found that the Diamond facemill finished really well. But profiling the contour had to be finished with carbide.

I even had a fire going in the machine from plunging down on the material with a 1" Diamond Rougher. Pecking will be used for the next time. HSS drills worked sufficiently for holes, and I used an HSS multi-flute counter sink for some deep CSs and burnt it out but finished the job with it nonetheless.

Still, with the Diamond tooling, I was able to take fully loaded cuts with the 1" at a 20 ipm. Air was the cooling method and as long as the tools were clean, I didn't experience any more fires...

[kentw]

We cut G10 here day in and day out, its a bear, but if done properly with the right tooling it becomes second nature. Be careful as tools dull, they will cause the material to de-laminate or split, depending on which way the grain is running on your parts. We use Mazak VTC20Bs and flood coolant on everything, these machines are setup perfect due to the traveling head and stationary tables, no abrasive wash over the ways. We have to clean the chip pans daily, but put "filter paper" on the grid so it catches most of it in the chip pans, we clean the tanks about every 2-3 months. If you use any kind of air pressure/blast for coolant you will fog up your shop with dust unless you have some sort of dust collection, and youll need to wear some sort of breathing protection. We use all carbide tooling, no diamond, and have very little problems. Altho we are experiencing an issue now with keeping some .039diameter holes straight going thru 3/8"thk G10. We use a 3/8diameter carbide burr to ruff the parts out (8000rpm and around 40ipm)and then standard 3/8, 1/4, and 1/8 carbide 4flute endmills (6500-8000rpms and around 30-40ipm) to finish. I tried to attach some photos but its not letting me. Ill try again to put some on here.

[kentw]

see photo