Experimental investigation of process parameters in maskless digital projection-based micro photochemical machining on spherical 100Cr6 steel surfaces

Abstract

Photochemical machining (PCM) is a machining process in which a mask or a chemical protective layer is employed along with a method of creating an image, while a chemical is used to dissolve undesired parts of a workpiece. In this research, the main goal is to employ the PCM method to create a groove on spherical 8 mm and 4 mm diameter workpieces made of 100Cr6 steel. Experiments were conducted using Positiv 20 as the photoresist agent, a tilted spray coating method to cover the workpiece with photoresist, a device used to bake photoresist onto 3D surfaces, a profile projector for measuring the dimensions, and an ML200 light projection device. The workpieces are exposed to light for 20 seconds, followed by development in a 10 g/L sodium hydroxide (NaOH) solution for 43 seconds. After the initial experiments, a problem, called “imperfect development,” arose, which was resolved by changing the exposure method of the pattern on the spherical workpiece. After the experiments were done and the “imperfect development” problem was resolved, a groove was formed on the surface of the workpiece which measured 3,072 µm in length, 636 µm in width and 52 µm in depth on an 8 mm diameter spherical workpiece, and a groove measured 3,084 µm in length, 648 µm in width and 51 µm in depth on a 4 mm diameter spherical workpiece.