LASER MILLING OF PRECISION MECHANICS FOR SPACE INSTRUMENTS

摘要

This paper presents how laser milling can replace conventional milling for producing selected features in thin-walled structures of space instrument parts. Example parts are shown. In the final stages of the manufacturing process the produced thin-walled structures require special attention to avoid vibration, unwanted deformation and even catastrophic destruction of the part. This requires careful planning of machining operations and fixture design which in turn can take considerable time. Laser milling is a slow material removal process. It is generally used only for finishing features that normal chip cutting tools cannot reach. However, in the case of the part having thin-walled structures, laser milling has the extra benefit of causing practically no deflection or vibration due to machining forces and consequently it requires minimal fixturing. Generally the laser beam should mill the material in the direction of its smallest depth to minimize recast and form errors that accumulate layer by layer. It is also possible to mill out solid chunks of material without fear of catastrophic collisions, unlike in chip cutting. This can reduce the milled volume thus speeding up the process considerably. Laser milling has special requirements with regard to the depth-width ratio of cavities, sidewall verticalness, and geometrical form of the raw stock. One must also consider where the laser beam hits after perforating the desired surface. In many cases combining laser milling with traditional machining is the fastest way to produce one-of-a-kind parts.