Machining of Micro Grayscale Images on Freeform Surfaces by Vibration-assisted Cutting

In this paper, a new vibration-assisted cutting method is proposed to machine micro grayscale images onto metal freeform surfaces. Taking advantage of a non-resonant vibration complaint cutting device used in a machining system, two vibration components can be used at the same time in the machining process. One vibration component is used to fabricate the freeform surface, while the other to generate the micro grayscale image on the freeform surface. Based on the working principle of this method, a toolpath generation algorithm is developed by considering the toolpath components for both the grayscale image and the freeform surface. Using the generated toolpath, image machining experiments have been conducted. Images have been successfully machined on saddle surfaces with an average surface roughness of 169 nm, which demonstrates the capability of the proposed method. This technology has potentially wide applications in machining master molds for mass production of patterned plastic components or drugs in the anti-counterfeiting field.