Cutting Aluminum Using a CNC Router

A computer numerical control (CNC) router is a machine that is designed to cut, mill, engrave and carve out shapes from various materials. It operates based on instructions programmed into a computer, allowing for much greater precision than even the most skilled woodworker or metalworker.

To create an object, a CNC router utilizes a cutting tool mounted on a spindle that rotates at high speeds to remove material from the workpiece. CNC software controls the movements of both the CNC machine and the workpiece.

While most people are familiar with the CNC router’s ability to cut wood, plastic and high-density foam, few know that cutting aluminum with a CNC machine is possible. In fact, cutting aluminum with a CNC machine offers several advantages over traditional cutting methods, such as precision, efficiency and the ability to make complex designs and cuts.

Follow these tips to get the best possible results when machining aluminum with a CNC router.

CNC Aluminum Cutting: Tips and Best Practices

Choose Carbide Cutters

Carbide can withstand higher temperatures than high-speed steel (HSS) cutters and run faster than both HSS and cobalt cutters, boosting your revolutions per minute (RPM). This can help reduce your machining time and increase your productivity. What’s more, carbide is a tough material that is highly resistant to wear and tear compared to HSS cutters, helping you save money on replacements.

Cool the Router Bit

CNC aluminum cutting creates a significant amount of heat, so it’s crucial to cool the bit regularly to prevent it from overheating. Using a mist coolant system is an excellent way to do this. It offers the added benefits of lubricating the system, removing chips as well as preventing swarf from adhering to the bit and the workpiece.

Use Smaller Cutters

Smaller cutters typically produce cleaner, more precise cuts. They create a smoother surface finish and, as a bonus, also help increase RPM.

Clear Chips Regularly

Swarf, or chips, are the debris from machining material such as aluminum. Swarf ranges in size from powder-like bits to large chips. When working with this metal, it is essential to clear the swarf from the workpiece once the machining cycle has finished.

Aluminum swarf tends to adhere to tools. This can cause poor-quality results and place excessive stress on the CNC machine. Further, aluminum chips can break cutters.

Another problem with letting chips accumulate is its effect on the CNC machine. It can cause the router to vibrate, resulting in inaccuracies in the workpiece. Worse, it could get caught in the machine and potentially damage it.  

For these reasons, it is also crucial to periodically clean the chips from the CNC router. The appropriate method to do so depends on the type of machine you have, but common approaches include manual brushing and using a water-soluble cutting fluid.

Keep Feed Rates Up

High spindle speeds are typically recommended when using a CNC machine for aluminum cutting. If you slow down the feed rate too much, the cutter’s contact time will increase. This will result in rubbing rather than cutting, which, in turn, can create a poor surface finish and shorten the lifespan of your cutting tool.

However, take care not to push the feed rate up too high. Otherwise, you will stress the cutting tool and cause it to wear out more quickly. You might also end up with a rough or inconsistent finish on the workpiece and dimensional inaccuracies in machined parts. Instead, take time to calculate the optimal feeds and speeds for your project.  

Make Multiple Shallow Passes

Aluminum is a heat-conductive material. This means it can quickly transfer heat to the cutting tool. When you make deep, fast cuts compared to shallow, slower ones, heat is generated more quickly, increasing the risk of damage to the bit.

It’s best rather to make multiple slow and shallow passes that prevent excessive heat transfer. Doing so also results in smaller chips per pass. It also reduces the risk of chip-related issues such as workpiece contamination and poor cutting efficiency.  

Choose a Cutter With Fewer Flutes

A cutter with too many flutes creates shallow flute pockets in which chips can build up and cause clogging. Instead, opt for a three-flute bit. The space between the flutes makes it easier for chips to escape.

Check the Workpiece Regularly

When using a CNC machine for aluminum cutting, check the workpiece frequently. This way, you can be sure the cut is going as planned, the router isn’t overheating and no chips have adhered to it.

CNC Aluminum Cutting: Safety Considerations

Aluminum is a fairly easy material to work with, and CNC machines do not pose as much risk as manual methods. However, care still must be taken when using a CNC machine for aluminum cutting. Here are some tips to follow to help ensure maximum safety:

• Always wear personal protective equipment (PPE). PPE for the eyes, ears, faces, hands and feet are a must. Some examples are face shields, closed-toe shoes, gloves, earplugs and safety glasses.
• Keep the work area clean. Machines kept free of debris function optimally. At the same time, cleanliness helps ensure their safe operation.
• Use the right cutting tools. Avoid altering your tools or using the wrong ones, as doing so can damage the machine or create a safety hazard.
• Avoid wearing loose clothing when working near the CNC router. Loose clothes and jewelry can get stuck in the machine’s moving parts, potentially resulting in injury.  
• Follow the manufacturer’s instructions. Your CNC router comes with specific operating instructions as well as safety information. Be sure to follow them to avoid damaging the machine and creating safety hazards.

Your Trusted Source for High-Quality CNC Routers

CAMaster is committed to facilitating and increasing your company’s productivity and efficiency by providing the best quality CNC routers and accessories. Our team offers exceptional technical support and service to help your machine shop achieve its business goals. 

Get in touch with us today to discuss our selection of Stinger and Cobra CNC routers for cutting aluminum.