Aluminum is one of the most widely used materials in current machining. Aluminum alloys possess many desirable characteristics: excellent machinability, high strength, corrosion resistance, recyclability, and the ability to maintain their softness, ductility, and strength at low temperatures. Therefore, CNC machining of aluminum parts is indispensable in many industries.
Applications of Aluminum and Aluminum Alloys:
Aerospace: Many aircraft components are made from machined aluminum due to its high strength-to-weight ratio.
Automotive Manufacturing: Similar to the aerospace industry, many components in the automotive industry, such as drive shafts, are also made from aluminum.
Electrical: CNC machined aluminum parts are frequently used as electronic components in household appliances due to their high electrical conductivity.
Food/Pharmaceutical: Aluminum parts play an important role in the food and pharmaceutical industries because they do not react with most organic substances.
Sports: Aluminum is commonly used to manufacture sports equipment, such as baseball bats and whistles.
Low Temperature: Aluminum maintains its mechanical properties even below freezing, making aluminum parts highly popular in low-temperature applications.
CNC Machining Methods for Aluminum Alloys:
For different aluminum alloy parts, various CNC machining methods can be used, including turning, milling, planing, drilling, and grinding.
Processing Precautions
Tool Material:
Carbide is the preferred material for cutting tools used in CNC machining of aluminum. Since aluminum is soft to cut, the cutting tools must not be too hard but still need to retain sharp cutting edges. Carbide tools meet this requirement due to two main factors: the grain size of the alloy and the proportion of the binder. Although larger grain sizes make the material harder, smaller grains enhance toughness and impact resistance by allowing cobalt to achieve a fine grain structure and material strength.
However, cobalt reacts with aluminum at high temperatures, forming built-up edges on the tool surface. To mitigate this, it is crucial to use carbide tools with an appropriate cobalt content (2-20%), ensuring the necessary strength while maintaining the required cutting edge durability. Carbide tools can withstand higher cutting speeds in aluminum CNC machining than steel tools. Besides the tool material, coatings are also important for cutting efficiency. Zirconium nitride, titanium diboride, and diamond-like coatings are suitable for tools used in aluminum CNC machining.
Feed and Speed:
Aluminum can endure very high cutting speeds, so it's recommended to maximize the cutting speed for aluminum alloys to reduce the formation of built-up edges, save time, lower part temperature, improve chip breaking, and enhance the finish of the machined surface. The choice of feed rate depends on the workpiece's machining precision, strength, and rigidity.
Cutting Fluid:
Even though aluminum is easy to machine, it should never be cut dry as this promotes the formation of built-up edges. Suitable cutting fluids for aluminum CNC machining are oil-based emulsions and mineral oils. Avoid using cutting fluids containing chlorine or active sulfur, as these elements can contaminate aluminum.
