Knowing these steps to cut aluminum with your CNC router can be the difference between a good day in the shop or dodging a broken cutter bit that’s been hurled across the room at you.
Take your time. Material removal rates will be slower than those on a mill, but since most CNC routers handle material larger than a standard mill, the speed to size ratio is a good trade-off.
Use the proper router bit. Use a 2 or 3 flute carbide endmill. They allow for a higher spindle speed on your router. Avoid cobalt and HSS cutters for working with aluminum.
Use smaller diameter cutters. Forget about 1/2″ endmills and go to 1/4″ or smaller. This allows higher feed rates and makes for smoother cuts.
Clear your chips. Keeping the chips clear of the cutter will avoid breaking endmills. If available, use an air blast aimed at the point of the endmill cut. This will keep your cut clear of chips that can build up and break your cutter.
Lubricate. The use of lubricating oil is highly recommended. It will not only make cutting easier and your success rate higher but aid in keeping your cutting edges sharp. For best results, set up a mist oiler that works with your air blast as you remove the chips.
Avoid overly slow feed rates. By slowing the feed rate too much, you run the risk of making your tool rub instead of cut. Because the spindle is going so fast, this is can be a larger risk for CNC router users than for mill users.
Learn from your errors. As with anything, there will be a learning curve. Success comes from persistence. Mistakes happen — the key is to always stay safe and learn from them.