A definitive guide to aluminum machining 

If you are working in a machine shop, aluminum is probably your favorite metal. If you are creating prototypes, I am sure you encounter aluminum or advise your clients to make aluminum parts.

Machined aluminum alloys are one of the most widespread practices in the manufacturing and prototyping industries. Our team has drafted up a small guide for you to revise about aluminum machining. Perhaps you’ll note something new for yourself. And if you are only being introduced to aluminum now, I am sure, you’ll find some useful info.

aluminum machiningThe characteristics of aluminum alloys for machining

Aluminum alloys are the bread and butter for all prototype manufacturers. They have good corrosion resistance, strength and they look good with that oxide sheen of theirs. Aluminum alloys are three times lighter than steel but they can withstand the same loads (However, if rigidity is a concern, you should rather stick to heavier metals).

But most importantly, they were made to be machined. They are quite soft and so the cutting tools live long even at high speeds. They conduct heat really well. It means that the heat will dissipate from the cutting zone faster. Why is it important? The hotter the cutting zone, the hotter the cutter is. And heated metals and carbides can withstand high loads for a shorter amount of time under the same stress.

Apart from that, once you’ve machined the part, it often doesn’t require any kind of coating or painting. The oxide film protects aluminum alloys from corrosion.

Why CNC machining of aluminum is so good for prototyping

Prototyping is a whole unique branch of manufacturing with its perks. You always have to remember that when you make a design verification or a proof-of-concept prototype, you don’t have to be so picky about the technology or the materials. And that is where aluminum machining comes in so handy. It’s the best choice for metal prototypes. Aluminum alloys are stronger than other soft metals that you can machine fast like brass or copper. And they have supreme machinability when we compare them with steel or titanium alloys. So, if you need a metal prototype of something, aluminum is your best choice in 60% of the cases.

Of course, if you are testing the mass-production technology for an object, you’ll have to use the final part material.

Surface treatments for aluminum prototypes

Despite having an oxide film, you may still want to apply some surface finishing operations to your part or prototype. And aluminum alloys actually have some additional options specific only to them. First of all, you can use the standard paint option. There are hundreds of aluminum paints of all the color tints. They offer both a great outlook if your surface finish isn’t very high and additional protection against the elements. Another great option is anodizing. You connect your metal to an electrical circuit in a specific way so that ions are removed from its surface. As a result, microscopic pores are formed in the material. This procedure actually increases the depth of the oxide layer. It makes aluminum alloys impervious to corrosion. But apart from that, you can add paint to the process and the paint will fill the pores. That makes for a great matted surface tinted with your desired color. And you can’t scratch the paint off. And last and not least, you can make a mirror-like surface on the aluminum part by grinding and polishing. Grinding will add high precision to your machined parts while polishing can create a mirror-like surface. There isn’t a lot that is better than the shiny metallic look.

The industries where aluminum machined parts are great

Aluminum Machined parts are coveted where mobility is required. That is because lighter vehicles need less fuel to move and are more maneuverable. So, aluminum parts are frequently used in the automotive, aerospace, and nautical industries. Apart from being lightweight, aluminum alloys are corrosion resistant so you can find them in a lot of marine structures. Those deal with saltwater and must cope with the oxidation of metals. Aluminum parts are used in practical appliances (irons, pans,etc.) They can withstand high temperatures and are lightweight. Aluminum alloys have great electrical conductivity so they are widely used for wiring and electronic devices.

The specifics of aluminum machining processes

Like all other metals, aluminum alloys have some specifics if you want to machine them. Here are some essential points that you need to check before starting to machine aluminum alloys.

  • Your spindle rate is over 12,000 rpm
  • Your tool has 2 or 3 flutes
  • Your feed rate is as fast as possible
  • Your coolant is a mist
  • You are using soft fixtures
  • You have triple checked chip removal
  • You are using Carbide inserts for the cutters
  • Your Chip Conveyor is Functioning


Let’s summarize all that has been said about machining aluminum. It is a great process for prototyping. The properties of aluminum alloys make them perfect for high-efficiency machining and that in turn is a good option for prototyping where the company that can produce a prototype faster will probably have the market advantage. Aluminum machined parts can be painted or anodized to get a great surface quality. Aluminum parts are used in a large variety of industries the main of them being the automotive and the aerospace. Machining aluminum has some specifics that you need to take into account. Namely, the majority of them are concerned with the cutting parameters being too low or the chip getting hard to remove. So in conclusion, aluminum is a great choice if you are designing a proof-of-concept or a design verification prototype of almost any metal machining device. However, we strongly advise using competent experienced machinists to process the parts.