Did you know that aluminum is one of the most frequently machined materials after steel? Using a CNC router for aluminum machining offers many advantages, but it can also be tricky. Its unique properties present both opportunities and challenges for machinists.
To optimize your CNC router aluminum results, you have to focus on various factors, including proper lubrication, right tooling, tool material, etc. With these adjustments, you can enhance precision and prolong tool life.
In this blog post, we’ll explore essential tips and techniques that will help you master CNC machining of aluminum. You’ll be able to get the best results and tackle these projects with confidence.
10 Tips for Better CNC Router Aluminum Results
It could be a struggle to get clean, burr-free cuts when machining aluminum with your CNC router. While the metal is easier to cut than steel, it can be difficult to work with if you don’t use the right techniques.
Let’s get into our 10 tips for how to optimize aluminum CNC routing. These adjustments will help you get precisely cut parts every time.
1. Use Proper Lubrication
To get the best result for CNC router aluminum, you must use proper lubrication. It helps the cutting tool glide smoothly through the material. Lack of lubrication can damage the cutting tools. It can also cause issues like built-up edges on the cutter, making it less effective. This buildup can lead to poor cuts and even ruin your project.
There are various types of cutting fluids you can use. Soluble-oil emulsions and mineral oils are popular choices for aluminum machining. They provide the necessary slickness without harming the metal. However, you must avoid using fluids that contain chlorine or active sulfur. These ingredients can stain aluminum, ruining its appearance and finish.
2. Cutting Wax for Single or Shallow Cut
Cutting wax can really enhance CNC router aluminum results, especially for single or shallow cuts. You just need to apply it to the surface where you’ll be cutting. It sticks well, so you don’t have to worry about it washing away, even if your router has a downward exhaust.
Why does cutting wax work so well? Because it provides excellent lubrication. It helps the router’s bit glide smoothly through the aluminum, reducing friction and heat. Less heat means less chance of damaging the material or tools. As a result, it can help achieve cleaner cuts.
Using cutting wax is particularly beneficial when you’re doing sheet metal cutting. The wax ensures that your first pass is smooth, allowing for better detail and accuracy.
However, if you’re planning to make deeper cuts or multiple Z levels, it’s best to use the wax primarily on the initial pass. This way, you still get the benefits without compromising your project’s overall quality.
3. Manage the Chip Formation
You can never get the best CNC router aluminum results if you can’t manage the chip accumulation. Chips can quickly pile up, especially when cutting deep pockets. If they aren’t removed, they can create real problems for your CNC router.
When you cut a deep groove in the workpiece, chips start to accumulate at the bottom. This buildup can cause your cutting tool to overheat. If that happens, the chips will stick to both the cutter and the workpiece. It not only damages your cutter but also makes the surface rough, creating misaligned parts.
To avoid these issues, consider making shallower cuts, as they produce fewer chips. Also, using a blast of compressed air helps keep the area clear. It can blow the chips away and keep the tool cooler, allowing for a cleaner cut.
4. Use the Right Tool Material
Aluminum is a soft metal, so it doesn’t require extremely hard cutting tools. Instead, what really matters is the tool’s ability to stay sharp. Carbide excels in this area, making it a top choice for machining aluminum.
The effectiveness of carbide tools comes down to their structure. The important factors here are the size of the carbide grains and the ratio of binder materials. Larger grains can make a tool harder, but smaller grains are better for toughness and resistance to impact. You need tougher tools for cutting aluminum because they can endure the stresses of cutting without chipping or breaking.
However, there’s a catch. Cobalt is often added to enhance the strength of carbide tools. But when cobalt heats up, it can react with aluminum, forming unwanted build-up on the tool. Ideally, a carbide tool should have about 2% to 20% cobalt. This ratio provides enough strength while reducing the adverse reactions with aluminum.
5. Use the Right Endmill
Your CNC router aluminum results also depend on selecting the correct endmill. For aluminum, two-flute endmills are often the best choice. They provide enough space for chips to flow out while still being strong enough to handle the material. If you need a bit more strength, three-flute endmills are also effective. They strike a good balance between chip clearance and rigidity.
On the other hand, single-flute endmills might not be the best for every job. While they allow for excellent chip removal, they lack the stability of two or three-flute options. This can lead to tool deflection, especially when using smaller endmills.
6. Increase Machine Rigidity
Having a sturdy CNC machine is essential for the best aluminum cutting results. An unstable machine can cause flexing and vibration, which makes it impossible to achieve clean, precise cuts.
To enhance your machine’s rigidity, consider adding extra ball screws and bearings. These components can help reduce movement and provide a more stable cutting environment. Shorter bits are less likely to bend under pressure, giving you more control. When shopping for end mills, look for “stub end” options.
Also, don’t try to override the cutting depth that your machine allows. For example, if your router machine is capable of cutting a depth of only 0.010 inches per pass, you should maintain that. Otherwise, you will only strain the machine.
7. Fix the Helix Angle
The helix angle of your cutting tool affects how well your machine can handle the material. If you get it right, you’ll see better results and smoother finishes.
A higher helix angle, like 45°, is great for finishing work. It helps the tool slice through aluminum with ease and creates a clean edge. However, it can also generate more heat and friction. This might lead to problems like chips sticking to the tool. That’s not what you want when aiming for precision!
On the other hand, a lower helix angle, around 35° or 40°, works well for roughing. It reduces heat buildup, which is beneficial during the initial cuts. But, it may not clear chips as effectively. If chips get trapped, they can interfere with your cut and cause damage.
You have to experiment with different angles to find out what works best for your specific project.
8. Set the Correct Clearance Angle
The clearance angle helps the cutting tool navigate the material without causing damage. If the angle is too large, the tool might dig in too much, leading to chatter and uneven cuts. On the flip side, if the clearance angle is too small, it can create extra friction, which generates heat. It can also slow down your process and lead to poor results.
For aluminum, aiming for a clearance angle between 6° and 10° works best. This range allows the tool to glide smoothly while preventing both chattering and excessive friction.
9. Optimize the Feeds and Speeds
Cutting speed refers to how fast the tool spins while cutting. Aluminum is unique because it can handle higher speeds compared to other materials. Increased cutting speed reduces the chances of unwanted edge buildup and workpiece overheating. A cooler workpiece means less risk of warping or deforming during the cut.
The ideal cutting speed varies based on the type of aluminum alloy you are using and the diameter of the tool. Always check your machine’s limits to find the best speed.
Feed rate is the distance the tool or workpiece travels with each revolution. This setting influences the finish of your cut. For rough but quick cuts, you can use a feed rate between 0.15 and 2.03 mm/rev. However, when it comes to finishing cuts, a slower feed rate of 0.05 to 0.15 mm/rev gives you a smoother surface.
Choosing the right feed rate depends on what you want to achieve. If you want a strong finish, ensure your workpiece is rigid enough to handle the chosen feed rate. Balancing feed rate with cutting speed is key to achieving the best CNC router aluminum results.
10. Don’t Use Tools with Fancy Coatings
Don’t use endmills coated with fancy materials. For example, gold TiN-coated end mills are meant for harder materials. They can become rougher and more reactive when cutting aluminum, making the metal stick to the tool. Similarly, coatings, like TiAlN, TiCN, and AlTiN, cause the same issues. While they may offer durability for tougher materials, their performance in aluminum machining isn’t great.
So, what should you use? Uncoated carbide tools are a solid option. They provide clean cuts without the complications of coatings. If you want to try coatings, look for ones specifically designed for aluminum, like ZrN or DLC.
Conclusion
Optimizing your CNC router results for aluminum machining is all about the right techniques and tools. We’ve discussed ten essential tips that will help you get cleaner and more accurate cuts. Remember to experiment with the settings of your machine because the cutting capacity varies from one machine to another.
Need aluminum precision machining parts for your project? Zintilon’s expertise and capabilities can deliver the exact components you need. Contact Zintilon to get custom metal fabrications and CNC machining services.
