In the metalworking industry, aluminum is widely used in aerospace, automotive manufacturing, electronics, and other sectors due to its lightweight and easy-to-machine properties. However, the "easy-to-machine" nature of aluminum often leaves engineers and operators puzzled: with countless milling tools available on the market, how can they select the right one to ensure machining quality, improve efficiency, and avoid unnecessary tool wear and material waste?

SPEED TIGER has released a detailed guide on selecting milling tools for aluminum machining, aiming to help manufacturers and engineers better understand aluminum's characteristics and choose the most suitable tools for different machining needs, thereby optimizing processes and reducing production costs.

Aluminum is one of the most abundant metals on Earth, and its lightweight and malleability make it ideal for numerous industrial applications. Aluminum is easy to mill, making it highly favored by manufacturers. Industrial aluminum is primarily divided into cast aluminum and wrought aluminum. Cast aluminum has higher flexibility and lower tensile strength, with lower production costs and higher content of other elements such as magnesium and silicon. Wrought aluminum, on the other hand, is a purer metal with lower wear resistance, high heat resistance, and superior cutting performance compared to cast aluminum.

The main challenge in machining aluminum lies in heat dissipation. Aluminum has a much lower melting point than steel, which can lead to friction-induced fusion between the tool and the material, damaging both the workpiece and equipment. Therefore, selecting milling tools with the correct geometry, coating, flutes, and angles is crucial.

A milling tool typically consists of a shank, neck, flutes, and cutting edges. The flutes are the part containing the cutting edges, extending from the tool's tip to the shank. The shank is the non-cutting cylindrical metal section from which the flutes are machined.

The geometry of a milling tool usually refers to its basic shape and design. The choice of shape depends more on the machining operation than the material itself. For example:

• Flat End Mills (Square End Mills): Suitable for plunge milling, contouring, slotting, and side milling.
• Long Neck End Mills: Reduce interference between the workpiece and tool, often used for cavity machining.
• Ball Nose End Mills: Ideal for creating rounded contours and flat-bottomed cavities.
• Corner Radius End Mills: Commonly used for mold milling, as they minimize the need for frequent tool changes when machining flat-bottomed pockets and rounded profiles.
• Tapered End Mills: Used for creating grooves, holes, and angled side milling.

Beyond the basic shapes, there are various tool options available for milling. For instance, chip breaker tools improve chip evacuation. Standard two-flute and three-flute end mills have serrated edges designed to scoop chips from the cutting surface, allowing higher speeds for better feed performance. Offset chip breaker geometry reduces chip size, enhancing chip evacuation while maintaining a semi-finished surface.

Additionally, high-balance end mills are engineered to achieve higher feed rates and RPMs. These tools feature radically altered head shapes, enabling cutting speeds of up to 33,000 RPM. To manage heat, many high-balance end mills incorporate coolant systems to lower blade temperatures. Some are also equipped with chip breakers for high-efficiency milling applications.

Coatings are surface treatments applied to milling tool heads to enhance hardness, reduce wear, extend tool life, and create a thermal barrier between the tool and workpiece. Some coatings also improve chip evacuation, further minimizing friction damage. However, few coating materials are suitable for aluminum.

Since aluminum is a soft metal, tool coatings do not need to provide significant additional hardness. Uncoated tools can drill aluminum effectively. However, due to aluminum's low melting point, coatings may sometimes be necessary to reduce excess heat.

• Tetrahedral Amorphous Carbon (TB) Coating: Features a high lubrication coefficient, allowing chips to move away from the material and reducing the need for coolant. Its diamond-like hardness also extends tool life.
• Aluminum Chromium Nitride + Silicon Nitride (nACRo): Suitable for high-heat applications. nACRo protects the tool head from wear and can withstand temperatures up to 1100°C before breaking down.

Generally, zirconium nitride (ZrN) is used for abrasive aluminum alloys. Amorphous diamond coatings improve lubrication and wear resistance, preventing edge rounding and delivering superior performance in non-ferrous applications.

When selecting a milling tool for aluminum, flute count is perhaps the most critical consideration. Flutes remove aluminum chips from the workpiece, preventing clogging.

Flutes refer to the number of cutting edges spiraling down the tool's body from its tip. For example, a single-flute end mill has one cutting edge, while a double-flute end mill has two, and so on.

The number of flutes determines a tool's rigidity, chip evacuation capability, wear time, vertical accuracy, and performance on soft and hard materials. Generally, more flutes increase rigidity but reduce chip evacuation. Compared to a six-flute end mill, a single-flute tool has poorer wear time, vertical accuracy, and surface roughness. However, they often perform better on softer materials like aluminum.

End mills for aluminum typically have two or three flutes. Fewer flutes lead to excessive wear, while more flutes hinder chip evacuation during high-speed drilling. However, as discussed below, exceptions exist.

Choosing between two-flute and three-flute end mills depends on the task. Two-flute end mills have long been the standard for aluminum milling, while three-flute tools are better for finishing. Ultimately, the decision comes down to preference and experience. Higher rigidity improves wear resistance, while fewer flutes enhance chip evacuation rates.

The helix angle is the angle between the tool's centerline and the tangent of its cutting edge. Tools with smaller helix angles have slower-wrapping cutting edges than those with larger angles.

Helix angle is crucial for aluminum machining. For aluminum cutting, machinists typically use 45°, 50°, and 55° helix angles. These angles minimize chatter and strike the best balance between rigidity and chip evacuation. Some professionals opt for variable helix angle tools for more reliable deep-hole drilling.

A shallow 15° helix angle provides excellent chip removal and cutting torque but weak axial tension. Steeper angles above 55° offer strong axial tension but often insufficient cutting torque for many aluminum applications.

For finishing, machinists usually choose 45° tools, as shallower cutting edges aggressively remove material. Chip evacuation remains adequate, while axial tension is higher.

SPEED TIGER offers a range of end mills specifically designed for aluminum. For example, the AP Square End Mill is a specialized aluminum-cutting tool manufactured in an ISO-9001-certified factory. Its single-flute design ensures superior chip evacuation, while the reinforced exterior adds strength and durability for high-intensity applications.

★ Key Features of the Single-Flute AP:

1. Optimized for high-speed machining and bulk material removal.
2. Excels in machining wood, aluminum, copper, plastics, brass, carbon steel (~HB225), alloy steel (HB225–325), and pre-hardened steel (up to HRC45).
3. Geometry and large chip pockets enable efficient chip removal, allowing higher feed rates and shorter cycle times.

SPEED TIGER also offers the N Series for non-ferrous applications like aluminum. The AL Carbide Drill enhances precision by reducing the space between the drill tip and cutting edge.

★ Special Design of the AL Drill:

1. Double margin—the second margin also has a cutting edge—ensuring smooth surface drilling and high-precision straight cuts.
2. High-rigidity design and expanded chip removal space.
3. Improved margin top positioning for higher drilling accuracy.

The ALC Carbide Drill shares the AL's double-margin cutting edge for high-precision straight cuts and smooth surface drilling. Additionally, it features a coolant hole to reduce temperatures in high-RPM applications. Enhanced margin top positioning improves hole accuracy in aluminum and copper alloy workpieces.

The N Series drills are suitable for various aluminum alloys, including A7075, AlZnCu1.5, AC, ADC, and A1070.

★ Special Design of the ALC Coolant-Through Drill:

1. Double margin for smooth surface drilling and high-precision straight cuts.
2. High-rigidity design and expanded chip removal space.
3. Improved margin top positioning for higher drilling accuracy.

The AUE High-Feed U-Type end mill significantly improves material removal rate (MRR) and surface finish due to effective chip evacuation at high speeds. Its robust teeth and double relief angle ensure outstanding productivity, with a 100% increase thanks to enhanced tooth hardness.

★ Key Features of the AUE Carbide End Mill:

1. Faster cutting speeds due to superior MRR, especially in slotting.
2. High-feed U-type design makes it ideal for aluminum and copper alloys.
3. Robust teeth and double relief angle—enhanced tooth hardness boosts productivity.
4. Alloy-optimized tooth design—whether roughing or finishing, surface finish is greatly improved by efficient chip removal.