When designing carbide end mills for aluminum, it is essential to comprehensively consider material selection, tool geometry, coating technology, and machining parameters. These factors ensure efficient and stable machining of aluminum alloys while extending tool life.
1.1 Carbide Substrate: YG-type carbide (e.g., YG6, YG8) is preferred due to its low chemical affinity with aluminum alloys, which helps reduce built-up edge (BUE) formation.
1.2 High-Silicon Aluminum Alloys (8%–12% Si): Diamond-coated tools or uncoated ultrafine-grain carbide are recommended to prevent silicon-induced tool corrosion.
1.3 High-Gloss Machining: High-rigidity tungsten carbide end mills with precision edge polishing are suggested to achieve a mirror-like surface finish.
2.1 Number of Flutes: A 3-flute design is commonly used to balance cutting efficiency and chip evacuation. For rough machining of aerospace aluminum alloys, a 5-flute end mill (e.g., Kennametal KOR5) can be chosen to increase feed rate.
2.2 Helix Angle: A large helix angle of 20°–45° is recommended to improve cutting smoothness and reduce vibration. Excessively large angles (>35°) may weaken tooth strength, so a balance between sharpness and rigidity is required.
2.3 Rake and Relief Angles: A larger rake angle (10°–20°) lowers cutting resistance and prevents aluminum adhesion. Relief angles are generally 10°–15°, adjustable depending on cutting conditions, to balance wear resistance and cutting performance.
2.4 Chip Gullet Design: Wide, continuous spiral flutes ensure fast chip evacuation and minimize sticking.
2.5 Edge Preparation: Cutting edges must remain sharp to reduce cutting force and prevent adhesion; appropriate chamfering enhances strength and prevents edge chipping.
3.1 Uncoated: In many cases, aluminum end mills are uncoated. If the coating contains aluminum, it may react with the workpiece, causing coating delamination or adhesion, leading to abnormal tool wear. Uncoated end mills are cost-effective, extremely sharp, and easy to regrind, making them suitable for short-run production, prototyping, or applications with moderate surface finish requirements (Ra > 1.6 μm).
3.2 Diamond-Like Carbon (DLC): DLC is carbon-based, with a rainbow-like appearance, offering excellent wear resistance and anti-adhesion properties—ideal for aluminum machining.
3.3 TiAlN Coating: Although TiAlN provides excellent oxidation and wear resistance (3–4 times longer life than TiN in steel, stainless, titanium, and nickel alloys), it is generally not recommended for aluminum because the aluminum in the coating can react with the workpiece.
3.4 AlCrN Coating: Chemically stable, non-sticking, and suitable for titanium, copper, aluminum, and other soft materials.
3.5 TiAlCrN Coating: A gradient-structure coating with high toughness, hardness, and low friction. It outperforms TiN in cutting performance and is suitable for milling aluminum.
Summary: Avoid coatings that contain aluminum (e.g., TiAlN) when machining aluminum, as they accelerate tool wear.
4.1 Chip Evacuation: Aluminum chips tend to stick; optimized flute designs (e.g., wavy edges, large rake angles) are required for smooth evacuation.
4.2 Cooling Method:
4.2.1 Prefer internal cooling (e.g., Kennametal KOR5) to lower cutting temperature and flush away chips.
4.2.2 Use cutting fluids (emulsions or oil-based coolants) to reduce friction and heat, protecting both tool and workpiece.
4.2.3 Ensure sufficient coolant flow to cover the cutting zone.
4.3 Machining Parameters:
4.3.1 High-Speed Cutting: Cutting speeds of 1000–3000 m/min improve efficiency while reducing cutting force and heat.
4.3.2 Feed Rate: Increasing feed (0.1–0.3 mm/tooth) boosts productivity, but excessive force must be avoided.
4.3.3 Cutting Depth: Typically 0.5–2 mm, adjusted per requirements.
4.3.4 Anti-Vibration Design: Variable helix, unequal flute spacing, or tapered core structures can suppress chatter (e.g., KOR5).
The core design principles of carbide end mills for aluminum are low friction, high chip evacuation efficiency, and anti-adhesion performance. Recommended materials include YG-type carbide or uncoated ultrafine-grain carbide. Geometries must balance sharpness with rigidity, and coatings should avoid aluminum-containing compounds. For high-gloss finishes or high-silicon aluminum alloys, optimized edge and flute designs are essential. In practice, performance can be maximized by combining appropriate machining parameters (e.g., high-speed, climb milling) with effective cooling strategies (e.g., internal coolant).
