OT - carbide router bits and aluminum

Risky

Bill Tindall, E.Tn.

"Carbide" will cut aluminum. At Misenheimer I have seen several foot diameter carbide blades being sharpened for Alcoa to cut aluminum ingots. The relevant question is whether the carbide composition, tooth geometry and tip speed used for wood is safe to use on aluminum. I think it likely these parameters are very different for aluminum.

A warning to others. Just because Tim has successfully sawed aluminum of some form and composition with some kind of wood blade don't assume you won't be showered by fractured teeth or bashed in the head by the piece after it galls to the blade. Been there and done that with a metal cutting blade on a table saw with too high rpm for aluminum. Aluminum stuck to teeth and it was a near mess I will never risk repeating.

Two things can happen. The carbide can fracture or become detached because the carbide is the wrong composition or the cutting geometry wrong . Machining aluminum requires special tooling and aluminum composition to prevent the aluminum from galling(welding) on the tool.

lubricant is the key

Dick Coers

When cutting aluminum, you need a lube to keep the material from sticking to the cutter. When I cut on a bandsaw, I smear an extra heavy coating of paste wax on the cut line. The heat melts the wax and lubes the blade. For router work, WD40 or a little kerosene or mineral spirits do a great job. It can get messy, but way better than picking chunks of aluminum off the cutter. Doing much cutting with aluminum with a router and you will want an O flute bit designed to cut aluminum. The slowest speed on a variable speed router helps, but the juice is the key to success.

Second Dick's comments

John in NM

Most routers go way too fast to cut aluminum well, but they will do it. First shop I worked for did a lot of aluminum cutting for making designer light fixtures. It worked, but it was horrible to do compared to using a milling machine - the bit speed meant a shower of hot chips. Lube will help some but they will still be hot - lube mostly helps prevent galling and improves cut appearance rather than reducing chip temperature.

I think I would use a spiral carbide bit myself. I might also pre-drill most of the waste out of the cut if I understand what you are doing. If you want to do just a single pass with the router rather than small step passes through the thickness of aluminum, pre-drilling will help a lot by reducing the amount of material the router bit is dragging on. Our machinist at work was just doing some big pockets in stainless steel and used this method, it was much faster as well as reducing wear on his more expensive tooling.

There's lube intended for this

Steve Elliott

The key to routing aluminum is lubricant. I had to rout 1/8" slots into the face of aluminum door fronts and used a stick lubricant from an industrial supplier. A heavy coat of the waxy lube solved the problem of aluminum sticking to the bit.

After I was done the shop floor was slippery for a couple of weeks because little bits of lube had been sprayed all over.

I'll post the brand of lubricant when I've been to the shop to check.

All of the above +

Barry Irby

Wear Eye Protection. Really, wear excellent Eye Protection and a face shield. If you get an embedded aluminum chip they can't use a magnet to pluck it out.