Aluminum is common in CNC machining due to its lightweight nature, versatile application and high corrosion resistance. It is also cost-effective as it is easier and faster to machine, leading to less spindle power and streamlining the manufacturing process.

Besides being lightweight, aluminum is also an excellent thermal conductor. It can therefore pull heat away from the cutting edge more effectively in comparison to steel. Read more on how these benefits can improve your shop’s efficiency and bottom line.

1.  Lightweight Strength

When compared to steel, aluminum is three times lighter. What does this mean for CNC shops? Thanks to this lightweight nature, spindle motors don’t have to work so hard, drawing fewer amps.

A perfect example is in aeroplane prototyping. Wikipedia data shows that every 1% reduction in weight equals approximately a 0.75% drop in fuel burn. Switching from steel brackets to aluminum will therefore reduce the component weight, translating to lower fuel burn and longer flight time.

Another example is when hobbyists use CNC milling at home. Lighter billets ensure faster tool changes and less vibration. As a result, it yields a smoother finish and tighter tolerance. Aluminum’s low density has a huge advantage in reducing machining effort and energy use.

Even with its lightweight nature, aluminum is still stronger compared to steel, as elaborated in the table below:

(Table 1: A comparison of Aluminum 6061-T6 and A36 Mild Steel properties)

2. Excellent Thermal Conductivity

Heat and precision do not go hand in hand. When cutting metal, too much generated heat can make tools dull, and this slows operations and productivity. But aluminum proves otherwise. A report from NIST confirms that 6061‑T6 aluminum conducts heat at approximately 150–167 W/m·K, which is triple the thermal conductivity of mild steel.

Since it conducts heat faster than steel, the rapid thermal dispersion keeps the tool-workpiece interface cool. The result is reducing the buildup edge and extending the cutter life.

In a high-speed pocketing operation, steel concentrates the heat at the cutting edge, forcing slower feed rates and frequent tool changes. In contrast, aluminum acts like a “heat sponge,” spreading heat into the rest of the piece. This way, you can achieve a clean surface finish on custom CNC parts without the cutter wearing out or getting too hot.

3. Versatile Applications

Aluminum’s unique blend of strength, machinability, and corrosion resistance opens doors across multiple industries, as shown below:

(Table 2: A quick breakdown showing which industries use CNC-machined aluminum parts)

4.  High Corrosion Resistance

According to NASA’s materials handbook, aluminum has a natural “rust-proof” shield (Al₂O₃) that forms a thin, hard layer when scratched. This dense oxide layer also protects the metal from the adverse effects of salt and moisture. In standardized salt-spray testing (ASTM B117), Aluminum 6061 exhibits a corrosion rate of just 0.10 mm/year over 200 hours. By contrast, uncoated steel can corrode at 1.0 mm/year or higher under the same conditions.

This resilience means:

• Little to no post-machining coating or plating needed
• Longer part life in marine, outdoor, or chemical-exposed environments
• Fewer reworks and returns due to surface pitting

5. Cost-Effective Machinability

Aluminum is easier to work with on CNC machines than most steels. It has a machinability index of roughly 360% relative to AISI 1212 carbon steel, 6061 outpaces mild steel’s ~72% index by nearly five times. You can spin the cutting tool at over 5,000 RPM without trouble.

The tool can also move into the metal more aggressively, which is helpful when taking thicker slices of material each pass. Tools also last longer. You can drill 1,500 holes before the drill bit wears out, whereas in steel, you’d only get about 500 holes. When you add up the savings on machine time, electricity and labor, you end up spending about 30% less per part.

Final Thoughts

This table summarizes the robust comparison of aluminum vs. steel in CNC machinery:

(Table 3: Comparing aluminum vs. steel in CNC machinery)

To sum up, using aluminum in CNC machinery speeds up your machining work, makes it more efficient and saves money. Machine tools run faster, take bigger bites out of the material and stay sharper longer. Based on statistics, shops of any size could see a noticeable boost in productivity and profits just by switching to aluminum.