Theoretical and Experimental Study of Ultrasonic Vibration-Assisted Laser Polishing 304 Stainless Steel

With the increasing requirements for the surface quality of the workpiece, many kinds of hybrid manufacturing have developed recently. Ultrasonic vibration-assisted laser polishing (UVLP) is a new hybrid manufacturing method. Different from the traditional method of applying ultrasonic vibration on the workpiece, this article applies ultrasonic vibration on the lens. Besides, the thermal mechanisms of the 304 stainless steel polished by traditional laser polishing (TLP) and UVLP were analyzed to reveal the influence of ultrasonic vibration on the polishing effect. The ultrasonic vibration lens transforms the laser polishing into an intermittent polishing process, which affects the laser energy density and the quality of the polished surface. This research was focused on the experimental analysis of the surface morphology and surface roughness of the 304 stainless steel that was processed by UVLP, and compared with TLP. And the effects of laser power, scanning speed, focus offset, and amplitude on the quality of the polished surface were obtained. The preferred process parameters of UVLP 304 stainless steel were obtained by the range analysis and variance analysis of the orthogonal experiment. Experimental results have shown that UVLP can reduce the surface roughness of 304 stainless steel from $2.777~\mu \text{m}$ to $0.512~\mu \text{m}$ at most. Thermal mechanism analysis results were verified by experimental results. Choosing appropriate processing parameters can effectively improve the quality of the polished surface, making the processing effect of UVLP significantly better than TLP.