How to cut aluminum with your CNC router

October 28, 2020

When you think of CNC routing, usually plastic and wood materials come to mind. But CNC routers also cut aluminum, a weaker metal, quite well.

At the same time, you have to watch out for a few things. As you might expect, cutting aluminum has its intricacies (versus wood and plastic). The first to be aware of is that aluminum is a “sticky” metal that wants to cling to your cutting tool. That makes removing chips a little trickier (which you’ll learn more about in a second).

With that in mind, here’s a few things to watch out for when you cut aluminum with your CNC router (Also, special thanks to Bob Warfield of CNC Cookbook for much of the info that appears in this post):

Take it Easy

In any business, your goal is to get the job done with high quality as fast as possible. At least initially, have the willingness to slow down your removal of material. Because, going fast only leads to mistakes and blemishes in your work. You don’t have to slow down your feeds and speeds. But how fast you actually remove your material should be slowed down.

Use a Feed Rate Calculator

When you cut aluminum, you have much tighter windows for your feeds and speeds. So, you want to be precise when you calculate them. For help, check out our feed rate calculator.

Obsess About Clearing Chips

Recutting chips is a leading cause of broken router bits. You can use a vacuum dust collection system. But remember, you can’t necessarily count on it to remove all chips. Before you start recutting, inspect every cut to make sure chips are clear.

Examine Cut Depths and Slotting

Chips become harder to clear as you cut deeper and closer to a slot. To ease the difficulty this causes, take more passes.

Bits with Fewer Flutes Make More Sense

When you cut aluminum, you create large chips. You can’t get around that. However, you can use a bit with 3 or fewer flutes. This allows more space between cutting edges, and that gives big chips more room to blow away. The fewer the flutes, the better. If you have 4 or more flutes, chips jam your flutes, and your bit breaks.

And Don’t Forget to Lubricate with Mist

Since aluminum likes to stick to your cutting edges, it makes sense to reduce this effect by using lubricating mist.

Now You’re Ready to Cut Aluminum

With these tips in mind, you’re now ready to cut aluminum, and experience a whole lot less frustration. Review them before you cut aluminum with your CNC router next time, learn from your mistakes, and improve your ability to cut aluminum.

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