Ultra precision machining refers to submicron (size error is 0.3-0.03? m. The surface roughness is ra0.03-0.005?m) And nanometer scale (accuracy error is 0.03?m. Surface roughness less than ra0.005?m) Precision processing. The technological methods and technical measures adopted to realize these processes are called super finishing technology. In addition, measurement technology, environmental protection and materials, people call this technology as super fine engineering. Ultra precision machining mainly includes three fields: ultra precision machining, such as ultra precision cutting of diamond tools, can process various mirrors. It has successfully solved the processing of large parabolic mirror used in laser fusion system and celestial telescope. Ultra precision grinding and grinding, such as coating surface processing of high density hard disk and large-scale IC substrate processing cnc products. The ultra precision special processing, such as the large-scale integrated circuit chip, is processed by the etching of electron beam and ion beam, with a line width of 0.1?m。 If the scanning tunnel electron microscope (STM) is used, the linewidth can reach 2-5nm.

a. Ultra precision cutting
Ultra precision cutting starts with SPDT technology, which supports the air bearing spindle, pneumatic sliding plate, high rigidity, high precision tools, feedback control and environmental temperature control, and can obtain the surface roughness of nanometer level. Diamond cutting tools are widely used in the processing of copper plane and aspheric optical elements, plexiglass, plastic products (such as camera plastic lenses, contact lenses, etc.), ceramics and composite materials. The future development trend is to use the coating technology to improve the wear of diamond tools in the process of hardening steel. In addition, micro tools are needed for the processing of micro parts such as MEMS components. At present, the size of micro tools can reach 50-100μm. But if the machining geometry is in submicron or even nanometer scale, the tool diameter must be reduced again. The development trend is to make the turning tool or milling cutter with super small cutter diameter by using nano materials such as carbon nanotubes.

b. Ultra precision grinding
Ultra precision grinding is a mirror grinding method developed on the basis of general precision grinding. The key technology is the dressing of diamond wheel, which makes the grinding particles have micro edge and equal high performance. The processing objects of ultra precision grinding are brittle and hard metal materials, semiconductor materials, ceramics, glass, etc. After grinding CNC Turning Services, a large number of extremely micro grinding traces are left on the machined surface, and the residual height is very small. In addition, the sliding, friction and polishing of the micro edge can obtain the machined surface with high precision and low surface roughness. At present, ultra precision grinding can process the roundness of 0.01μm. Dimension accuracy 0.1μM and surface roughness are ra0.005μM cylindrical parts.

c. Ultra precision grinding
Ultra precision grinding includes mechanical grinding, chemical mechanical grinding, floating grinding, elastic emission processing and magnetic grinding. The key conditions of ultra precision grinding are almost vibration free grinding movement, precise temperature control, clean environment and fine and even grinding agent. The spherical surface degree of ultra precision grinding is 0.025μm. Surface roughness Ra up to 0.003μm。

d. Ultra precision special processing
Ultra precision special processing mainly includes laser beam processing, electron beam processing, ion beam processing, micro EDM, fine electrolysis and electrolysis grinding, ultrasonic electrolysis, ultrasonic electrolysis grinding, ultrasonic EDM and other complex processing. Laser and electron beam processing can realize drilling, precision cutting, forming cutting, etching, lithography exposure and laser anti-counterfeiting mark processing; Ion beam machining can realize atomic and molecular level cutting; The micro discharge machining can remove the extremely fine metal materials, and can process the micro axis, hole, narrow seam plane and surface; Fine electrolysis can achieve nanometer precision, and the surface will not produce processing stress. It is often used in mirror polishing, mirror thinning and some occasions where stress-free processing is needed.

The countries with advanced position in the world in ultra precision machining technology are the United States, the United Kingdom and Japan. The ultra precision processing technology in these countries is not only the overall set level high, but also the degree of commercialization is very high. In the 1950s, the ultra precision cutting technology of diamond tools was not developed in the United States, which is called "single point dia Mond turning" or "micro inch technology" (1 micro inch = 0.025 μ m) The ultra precision machine tool for the main axis of air bearing is developed to process the laser fusion reflector, tactical missile, spherical and aspheric parts for manned spacecraft. The Cranfield Institute of Precision Engineering (cup), affiliated to Cranfield Institute of technology, is a unique representative of the UK's ultra precision machining technology. For example, nano center produced by cup can not only carry out ultra precision turning, but also has grinding head, and can also be ultra precision grinding. The shape precision of workpiece can reach 0.1 μ m. The surface roughness Ra < 10 nm. Japan's research on ultra precision machining technology started late than that of the United States and the United Kingdom, but the world has the fastest development in the world. Beijing Machine Tool Research Institute is one of the main units in the research of ultra precision machining technology in China. It has developed a variety of ultra precision machine tools, components and related high-precision testing instruments, such as precision of 0.025 μ The precision bearing, jcs-027 ultra precision lathe, jcs-031 ultra precision milling machine, jcs-035 ultra precision lathe, ultra precision lathe numerical control system, photocopier drum processing machine, infrared high power laser reflector, ultra precision vibration displacement micrometer, etc. have reached the leading domestic and international advanced level. Ultra precision diamond cutting, diamond tool crystal orientation and cutting edge of Harbin University of Technology.

The grinding and the on-line dressing technology of diamond micro powder grinding wheel electrolysis have been studied. Tsinghua University has made in-depth research on the ultra precision machining equipment of integrated circuit, disk processing and testing equipment, micro displacement table, ultra precision belt grinding and grinding and polishing, ultra precision grinding of diamond micro powder grinding wheel, ultra precision cutting of non-circular section, etc., and has related products. Compared with the United States and Japan, there is still a great gap in the ultra precision machining technology in China, especially in the ultra-precision machining of large optical and non-metallic materials, especially in the efficiency and automation technology of ultra precision machining.

Ultra precision machining will develop to the direction of high precision, high efficiency, large scale, miniaturization, intelligence, process integration, online processing and testing integration, green and so on.

a. High precision and high efficiency.
With the continuous progress of science and technology, the requirements for precision, efficiency and quality are becoming higher and higher. High precision and high efficiency become the eternal theme of ultra precision machining. The machining efficiency can be improved by ultra precision cutting and grinding technology. CMP and EEM technology can ensure the machining accuracy. However, the semi fixed grinding particle processing method and the composite machining methods such as electrolytic magnetic grinding and magnetorheological abrasive flow machining have become the trend of ultra precision machining because of the processing methods which can take into account efficiency and precision.

b. Large scale and miniaturization.
Due to the development of aerospace and other technologies, large optoelectronic devices require large-scale ultra precision processing equipment, such as the large-scale optical device ultra precision machining machine with a diameter of 2.4-4m developed in the United States. At the same time, with the development of micro mechanical electronics, photoelectric information and other fields, ultra precision machining technology has developed to miniaturization, such as micro sensors, micro drive elements, power devices, micro aerospace devices, etc.

c. Intelligent.
It is always the goal of manufacturing to reduce the dependence of machining results on artificial experience by intelligent equipment. The intelligence degree of processing equipment is directly related to the stability and efficiency of machining, which is more obvious in ultra precision machining.

d. Process integration.
Nowadays, the competition between enterprises tends to be hot, and high production efficiency is becoming the condition for enterprises to survive CNC Drilling Services. In this context, there is a call for "grinding for research" or even "throwing by grinding instead of throwing". On the other hand, the trend of using a single equipment to complete a variety of machining (such as turning, drilling, milling, grinding, finishing) is becoming more and more obvious.

e. Integration of online processing and testing.
Because of the high precision of ultra precision machining, it is necessary to develop the integrated technology of online processing and testing to ensure the quality of products and improve the productivity. At the same time, because the accuracy of the processing equipment is difficult to meet the requirements sometimes, the online detection, working condition monitoring and error compensation can improve the accuracy and ensure the requirements of processing quality.

f. Green.
Abrasive processing is the main means of ultra precision machining. The manufacturing of abrasive itself, the consumption of abrasive in processing, the energy and material consumption caused by the processing, and the processing fluid used in processing have caused a great burden on the environment. China is the first country in the production and consumption of abrasive and abrasive tools. It has become an urgent task for developed countries and Taiwan to control the waste liquid, exhaust gas discharge and standards of semiconductor manufacturers in Taiwan. Therefore, researchers from all over the world have carried out research on the recovery and treatment of waste liquid and waste gas produced by CMP processing. The green ultra precision processing technology reduces the environmental burden and improves its vitality.