Need Help!- Machining copper

[erkiwi]

What is the best cutter and speed to cnc machine a copper head gasket 1mm thick?

[holbieone]

i would dull your cutters a little before cutting

copper will grab a sharp tool

[Karl_T]

dull is the wrong term. Grind them for 0 rake angle for just a few thou. for this part, make a sandwich, sacrifical material above and below. HSS endmills would work well.

[dertsap]

i would use a new 2flt solid carb , you'll need to keep a good chip load but not too heavy that the chips stick to the tool , if you go too light of a chipload you face premature cutter wear due to the fact cooper is quite abrassive and it will result in poor finish and heavy burrs ,use a lot of coolant

[skyline]

We machine alot of Cu at work and the best tool for the job "albeit quite expensive" is a single crystal diamond endmill. I've gotten 20nm surface finishes with it before, verified on a white light interferometer.

[K&Y]

Originally Posted by skyline We machine alot of Cu at work and the best tool for the job "albeit quite expensive" is a single crystal diamond endmill. I've gotten 20nm surface finishes with it before, verified on a white light interferometer.

Very true. Single crystal diamond will give you an optical finish, if the machine in question is rigid enough. If you aren't quite in need of an optical finish however, a PCD-tipped endmill will do a fantastic job on copper, and will outlast carbide at least 100 times.

[SRT Mike]

We machined a ton of 0.062" (1.6mm) copper into a pretty complex shape. We tried everything and eventually got awesome results - looked like it had been laser cut! How?

Machined a block of 6061 with the cut-out pattern relieved so that when the copper is mounted on top, the toolbit wasn't cutting into the bottom plate.

Then took pieces of copper - made sure to keep them FLAT. Lay the block of aluminum on a hot plate - let it get hot. Take a glue stick and rub it over the front, covering it in glue - then stick the copper sheet onto it. Use a dense rubber roller (that wont melt) to make sure it's stuck down nice. Then machine away! We got a perfect finish using a 1/16" end mill (2 flute) from McMaster - it had a purplish coating, it was specifically said it was appropriate for soft gummy materials. When the bits were new the finish was perfect. Only when they got dull (after maybe 50+ pieces) did you see the slightest hint of any tearing.

The nice thing about the glue is it holds the entire surface of the material and does not impact the cutter at all. If you make a template that bolts on top, it can allow the copper to deform at the cut line and give a ragged edge.

To remove the copper, just put your block back on the hot plate and let it melt the glue, then pull the copper off. To get the glue off the copper, put it in a tub of acetone and let it sit for a few hours - the hot melt glue will just flake right off and you are left with a great finish on a perfectly flat piece of copper with no clamp marks and no tool marks.

I can't take credit for this idea, it was given to me by a member here and it worked awesome.