Turning of aluminum and aluminum alloys
Turning aluminum and aluminum alloys is a vital component of the metalworking industry. Due to their excellent overall performance, aluminum and aluminum alloys are widely used in industries such as aerospace, automotive manufacturing, and electronic communications. Aluminum and aluminum alloys have a low density (approximately 2.7g/cm³), only one-third that of steel. Parts produced through turning can effectively reduce equipment weight and improve energy efficiency. Furthermore, aluminum and aluminum alloys exhibit excellent electrical and thermal conductivity and corrosion resistance, and surface treatment can impart an aesthetically pleasing appearance and enhanced weather resistance. A notable feature of turning aluminum and aluminum alloys is their low cutting forces, approximately one-third to one-half those of steel. Consequently, the required machine power and fixture rigidity are lower, allowing for high-speed cutting to improve production efficiency. A new energy vehicle manufacturer, using high-speed turning, reduced the single-piece processing time for turning aluminum alloy motor housings from eight minutes using conventional methods to three minutes, significantly increasing production line capacity.
When selecting tools for turning aluminum and aluminum alloys, the material’s properties must be considered. Aluminum and aluminum alloys exhibit good plasticity and are prone to tool sticking. Therefore, turning tools must exhibit high sharpness and a low coefficient of friction to reduce built-up edge. High-speed steel tools, while sharp, suffer from poor wear resistance, making them suitable for low-speed precision turning. Carbide tools, particularly tungsten-cobalt (YG) carbide, are the preferred choice for turning aluminum and aluminum alloys. Their high toughness and anti-sticking properties effectively address aluminum alloy machining requirements. Common grades include YG6 and YG8. For high-precision, high-finish surface machining, diamond tools can be used. Their exceptional hardness and wear resistance enable mirror-finish turning with surface roughness reaching Ra0.02-0.05μm. An electronic equipment manufacturer uses PCD (polycrystalline diamond) tools when turning aluminum alloy housings, achieving a mirror-finish finish on the housings, eliminating the need for subsequent polishing and saving processing costs.
The process parameters for turning aluminum and aluminum alloys significantly impact machining quality and efficiency. Cutting speed is a key parameter, and a higher speed is generally recommended to avoid built-up edge. When turning aluminum alloys with high-speed steel tools, the cutting speed can be controlled at 50-100 m/min; carbide tools can be increased to 100-300 m/min; and diamond tools can even reach high-speed cutting speeds of 500-1000 m/min. The feed rate should be selected based on surface quality requirements. For finish turning, a feed rate of 0.05-0.1 mm/r can produce a finer surface texture; for rough turning, it can be increased to 0.1-0.3 mm/r to improve removal efficiency. The depth of cut is determined by the machining allowance: 1-5 mm for rough turning and 0.1-0.5 mm for finish turning. When turning aluminum alloy components, an aviation company uses a parameter combination of a cutting speed of 250m/min and a feed rate of 0.1mm/r, which not only ensures surface quality but also achieves efficient processing.
Special attention should be paid to the cooling, lubrication and chip removal technologies when turning aluminum and aluminum alloys. Due to the good thermal conductivity of aluminum alloys, the cutting heat is easily carried away by the workpiece and chips. However, high temperatures will still be generated during high-speed cutting, and aluminum chips are soft in texture and easily entangled on the tool or workpiece, affecting processing quality and safety. Therefore, a cutting fluid with good lubrication and cooling properties is required. Either an emulsion or a special aluminum alloy cutting fluid can be used, and its flow rate should be sufficient to effectively flush the chips. For deep hole or cavity turning, a high-pressure cooling system can be used to spray the cutting fluid directly into the cutting area to prevent chip accumulation. When a motorcycle factory was turning aluminum alloy wheels, it successfully solved the problem of aluminum chip entanglement by optimizing the cutting fluid spray angle and pressure, thereby improving the stability of the processing process by 40%.
Different types of aluminum alloys have varying turning properties, requiring tailored machining strategies. Pure aluminum (such as 1050) is relatively soft and prone to tool sticking and burrs during turning. Sharp tools and high cutting speeds are required, with post-process deburring required. Hard aluminum alloys (such as 2A12) contain alloying elements like copper and possess high strength and hardness. Therefore, cutting speeds should be appropriately reduced during turning, and carbide tools with good wear resistance should be selected. Cast aluminum alloys (such as ZL104) may contain internal pores or inclusions, making tools susceptible to impact during turning. Large rake and clearance angles should be used to enhance the tool’s impact resistance. A rail transit company, processing high-speed aluminum alloy profiles for 6061-T6 aluminum alloy, employed specialized turning tools with large rake angles and optimized cutting parameters, resulting in a 25% improvement in machining efficiency and part dimensional accuracy within ±0.03mm. With the application of aluminum alloy materials in more fields, turning technology is also constantly innovating. The application of green processing technologies such as high-speed dry cutting and low-temperature cold air cutting will further promote the environmental protection and efficiency of aluminum and aluminum alloy processing.
