Research on high-energy nanosecond laser polishing technology for cast aluminum alloy wheels

Cast aluminum alloy wheels are widely used in automotive manufacturing due to their lightweight and high-strength properties. However, their surface quality is significantly affected by casting defects such as porosity and oxidative inclusions. In this study, a self-developed high-energy nanosecond laser polishing system was employed, incorporating a beam homogenization system based on a cylindrical microlens array. This system transforms a Gaussian-distributed laser beam into a uniform linear beam spot, effectively eliminating issues such as overburning caused by excessive central energy and insufficient edge energy. Laser polishing experiments were conducted on cast aluminum alloy wheel samples by varying laser energy density, scanning speed, and number of scans. The results demonstrated that optimal polishing was achieved under the following parameters: single pulse energy of 493mJ, repetition frequency of 5.6 kHz, initial scanning speed of 20 mm/s with one scan, followed by accelerated scanning at 40 mm/s with one additional scan after cooling. This process reduced the surface roughness (Ra) from an initial 9 μm to 0.9 μm, achieving a remarkable 90% reduction. This study provides theoretical and practical guidance for green and high-efficiency laser polishing of aluminum alloy wheels, offering a promising solution to enhance surface quality while addressing energy distribution challenges in laser processing.