Innovative micro-tool manufacturing using ultra-short pulse laser ablation

Abstract

Abstract The continuously growing demand for micro-electro-mechanical systems (MEMS) with decreasing feature sizes necessitates adjusted manufacturing solutions. Micro-milling fulfills the high requirements for precision and reliability placed on the final product. The employed tools have diameters in the range of 50–300 μm and are commonly manufactured by grinding. However, a reduction in tool diameter leads to a decrease in stiffness in the fourth power and the introduced load in grinding causes a high scrap rate. Furthermore, the flexibility in tool design is limited to the attributes of the grinding wheel. These restrictions in micro-tool manufacturing can be avoided by using ultra-short pulse (USP) laser ablation. This process allows a force-free 2-D and 3-D machining across a broad range of materials without wear formation. By using a USP laser, a wide range of customer-oriented applications in the micrometer scale can be addressed. Also, it leads to precise ablation with minimal thermal and mechanical damage. This paper provides knowledge on the manufacturing of micro-tools made of tungsten carbide with small diameters and high aspect ratio. For the desired tool geometries, necessary process parameters are evaluated and their physical limits are shown and discussed. An innovative CAM-system has been programmed to allow the manufacturing of advanced geometries using a 4-axis laser machine test bench developed by ETH Zurich. A 515 nm wavelength laser beam is capable of providing flawless tools with diameters as low as 50 μm and aspect ratios up to 6. Due to precise calibration, the tool run-out is decreased to