Hi,

Well, the topic says it all. I have been milling in POM and other plastics but now I need to make some parts out of aluminum.

I have a Proxxon MF 70 with 23 stepper motors on each axis.

Could anyone give me some advice on feedrates (mm/sec) and approperiate milling depth for a 3mm tunsten milling bit (Proxxon original)

Thanks for your help,

Christian,

I would start off slowly and work your way up. A good start would be about 8,000 - 10,000RPM and a 100 mm/min ( 1.6 mm/sec) feed rate. I would advise that you use a cutting medium like kerosine or WD-40 in a spray bottle. If you can get your hands on a good soluable oil (hard to find in Europe), that would work as well. If your machine is not vibrating at the above speeds and feeds, then you can try increasing your feedrate, if your machine is vibrating, either drop your feed rate or increase your spindle speed. Remember if you are direct plunging, do not plunge at the same feed rate you are cutting at, try 25 - 50 mm/min (0.4 - 0.8 mm/sec) for plunging. Let us all know how you went.

Christian, Dave's numbers look like a good starting point. By the way, it's nice to see someone remember how well kerosene works on aluminum. Seems like more and more folks today are convinced nothing less than some $100 per gallon wonder-goo will facilitate metal cutting. You may also find it necessary to put an airstream on the cutter to keep the cut free of chips. I don't do much cutting with endmills this small, but to scale down from practical experience, I'd say your depth of cut can safely be at half the cutter diameter for a starting point. With experience you may find you can take a deeper cut, but this depends on the material and the specific cutter. One thing's for sure though......nothing will jam chips and break a cutter quicker than a too deep slotting cut. Also, keep an eye on the edge sharpness of the cutter until you get some feel for how long you can run one until it's dull. Some types of aluminum are surprisingly abrasive to cutting edges. Lots of folks will say carbide is the only way to fly, but I've found the toughness and edge-holding ability of cobalt bearing HSS cutters can make them outperform carbide in aluminum in many instances.