Research on fabrication technology of tungsten micro-hole with large aspect ratio based on micro-EDM

The typical characteristics of pinholes used for X-ray imaging are micro-diameter and large aspect ratio. Pure tungsten is generally used to prepare them, but tungsten is difficult to prepare using traditional methods due to its high hardness and strength. Although micro-EDM has certain advantages in machining micro-holes in difficult materials with large aspect ratio, the problem of debris accumulation makes solving the issue of micro-hole taper difficult. To manufacture micro-holes with large aspect ratio and aperture consistency, a new machining process was proposed by combining micro-EDM technology and welding technology. Two semi-circular groove workpieces with the same depth and width were machined using combined manufacturing technology and then welded together to obtain complete micro-holes. This combined manufacturing technology successfully processed pure tungsten material to achieve micro-holes with apertures of 171.45 mu m and 174.58 mu m and a length of 40 mm.