The miniaturization of structures and parts is one of the development trends in the field of technology. The development of economically viable micro-machining technology is of great significance for the development of micro-technology. At present, industrial micro-fabrication technology is mainly used in the semiconductor industry, they are only economical for mass production; the micro-fabrication technology used in the printing plate-making industry has very much the processing geometry and the materials that can be processed. Big limitations. Compared with these two manufacturing technologies, micro-machining can make up for the above shortcomings. Therefore, the development of micro-machining technology is a new field of micro-fabrication technology. Next page
The first batch of micro-machining equipment was developed in the United States in the late 1960s and was mainly used to machine the surface of optical parts, which led to the development of super-finishing technology. At present, micron and submicron precision and surface roughness of tens of nanometers are achieved in the processing of optical, electronic and mechanical parts. In the late 1980s, the Carusle Research Center in Germany used micro-cutting to machine fine textures on the surface of micro-components to make micro-heat exchangers: they used single crystals on copper or aluminum foil on a cylinder. The tip of the diamond is grooved and eventually made into a miniature, highly efficient heat exchanger.
Until the 1990s, micro-cutting was mainly the processing of non-ferrous metal parts with diamond tools. With the continuous expansion of the application of microtechnology, it is required to process more diverse materials, especially the fine cutting of steel and ceramics, which has become the development direction of micro cutting technology.
Diamond tools - near-ideal cutting materials
In the field of super finishing, single crystal diamond tools are almost the only practical tools. The low friction coefficient and high thermal conductivity of the diamond are beneficial to the cutting process; it has a high hardness and a sharp edge that can be processed close to the atomic size, and the sharp edge is a must in the field of micromachining. Key technology. A sub-micron sharp edge can produce surface roughness on the order of a few nanometers. The sharp edge and low friction coefficient greatly reduce the cutting force, which is conducive to the precision of micro-machining and reduces the rigidity of super-finishing machine tools.
Diamond tools are suitable for processing aluminum, pure copper, brass and copper-nickel alloys. Copper-nickel alloys have a high hardness and excellent surface quality during processing. Diamond is not suitable for processing ferrous metals. In order to enable diamond to process steel, some devices are being developed, and one device works well. It superimposes an ultrasonic vibration on the movement of the tool, which greatly reduces the contact time of the tool during cutting, thereby reducing the cutting temperature and inhibiting the conversion of diamond to graphite.
Micro-cutting is derived from ordinary cutting
The knowledge of micro-cutting is actually obtained from ordinary cutting operations, including turning, milling, drilling, grinding, and in some cases, micro-machining is also sawing or planing. At present, the most researched and most mature is super-fine turning. For example, a non-ferrous metal mold for pressing a Fresnel lens or a sample for surface roughness is produced.
By superimposing a high-frequency vibration driven by a piezoelectric crystal into the feed mechanism, when it is properly synchronized with the spindle rotation frequency and vibration, a non-rotationally symmetrical machining surface can be produced to achieve a polished mirror surface. At present, the technical level of ultra-precision turning has been able to machine extremely fine shaft diameters. Milling is also considered to be the most flexible processing method in microfabrication. A single-toothed diamond disc milling slot can be used to machine grooves that intersect at various angles as compared to the previously described grooves on the film. It can be used to make molds for pressing optical grid structures, such as 100 lines per mm. Commercially available disc milling cutters have a minimum width of about 100 μm.