Ultra-precision machining is a necessary means of achieving high shape accuracy, surface accuracy and surface integrity. Advanced ceramic or optical glass components used in precision optics, mechanical, and electronic systems typically require very high shape accuracy and surface accuracy (eg, 0.1 nm surface roughness) and a small process metamorphic layer. Mastering the material removal rules and damage layer characteristics during ultra-precision machining is very important to improve the stability and economy of processing. The ultra-precision cutting, ultra-precision grinding and ultra-precision grinding and polishing techniques in ultra-precision machining are reviewed, and various typical processing methods and material removal mechanisms are highlighted. The above-mentioned types of ultra-precision machining methods are compared from the viewpoints of machining accuracy and machining efficiency, and a semi-fixed abrasive grain processing technique for achieving high-efficiency precision machining is introduced. Forecast the development trend of ultra-precision machining.
1. Preface
Ultra-precision machining technology is an important supporting technology for modern high-tech warfare, the basis for the development of modern high-tech industries and science and technology, and the development direction of modern manufacturing science. High-performance weapons supported by ultra-precision machining technology, processes and results for the first Gulf War (1992), the Kosovo War (1996), the Afghanistan War (1999), and the Second Gulf War (2003) Played a decisive role. The three generations of semiconductor devices supported by ultra-precision processing technology laid the foundation for the development of electronics and information industry. The development of modern science and technology is based on experiments, and almost no test equipment and equipment are required to support the ultra-precision machining technology. From macro manufacturing to micro-manufacturing is one of the future development trends of the manufacturing industry. At present, ultra-precision machining has entered the nano-scale, and nano-manufacturing is the forefront of ultra-precision machining. The developed countries of the world attach great importance to it. The recently launched research programs include the 2001 NNI (National nanotechnology initiative) program, the UK's Interdisciplinary research collaboration in nano-chnology, and the 2002 Japan Nanotechnology Support Program. The current ultra-precision machining is based on the premise of not changing the physical properties of the workpiece material to obtain ultimate shape accuracy, dimensional accuracy, surface roughness, surface integrity (no or minimal surface damage, including microcracks and other defects, residual stress). Organizational changes)
For the goal.
The research content of ultra-precision machining, that is, the factors affecting the precision of ultra-precision machining include: ultra-precision machining mechanism, processed materials, ultra-precision machining equipment, ultra-precision machining tools, ultra-precision machining fixtures, ultra-precision machining inspection and error Compensation, ultra-precision machining environment (including constant temperature, vibration isolation, clean control, etc.) and ultra-precision machining processes. All along, domestic and foreign scholars have carried out systematic research around these contents.
At the International Production Engineering Conference in 1983, TANIGUCHI described the ultra-precision machining conditions at that time and predicted the development trend of ultra-precision machining. In the following 20 years, ultra-precision machining technology has flourished. This paper reviews the current state of ultra-precision machining. Section 1 describes the development of ultra-precision machining and its driving factors. Section 2 introduces ultra-precision machining materials with a focus on advanced ceramic materials. Section 3 classifies ultra-precision machining into ultra-precision machining, ultra-precision grinding and ultra-precision grinding and polishing, and introduces typical machining techniques (generalized ultra-precision machining also includes micro-machining technology). Section 4 compares the above-mentioned types of ultra-precision machining techniques from the perspective of machining accuracy and machining efficiency, and introduces the semi-fixed abrasive processing method. Section 5 predicts the development trend of ultra-precision machining.
2. Development of ultra-precision machining
The development of ultra-precision machining has gone through the following three stages.
(1) The technology pioneering period from the 1950s to the 1980s. In the late 1950s, due to the development of cutting-edge technologies such as aerospace and defense, the United States took the lead in developing ultra-precision machining technology and developed ultra-precision cutting of diamond tools, Single Point Diamond Turning (SPDT). Also known as "micro-inch technology" for processing laser nuclear fusion mirrors, tactical missiles and manned spacecraft spherical, aspherical large parts. Since 1966, Union Carbide in the United States, Philips in the Netherlands, and Lawrence Livermore Laboratories in the United States have launched their own ultra-precision diamond lathes, but their applications are limited to experimental research by a few large companies and research units, and for defense or scientific research purposes. The main products are processed. During this period, the diamond lathe was mainly used for the processing of soft metals such as copper and aluminum, and it was also possible to process workpieces with complicated shapes, but only for axially symmetric workpieces such as aspherical mirrors.
(2) The early 1980s to the 1990s was the beginning of private industrial applications. In the 1980s, the US government promoted the commercialization of ultra-precision processing equipment by several private companies such as Moore Special Tool and Pneumo Precision, and several Japanese companies such as Toshiba and Hitachi and Cranfield University in Europe also launched products. These devices began to be manufactured for general consumer industrial optical component goods. However, the ultra-precision processing equipment at this time is still noble and rare, and is mainly ordered in the form of a dedicated machine. During this period, in addition to diamond lathes that process soft metals, ultra-precision diamond grinding that can process hard metals and hard and brittle materials has also been developed. The technology features a high-rigidity mechanism for ductile grinding of brittle materials with minimal depth of cut to achieve nanoscale surface roughness for hard metals and brittle materials. Of course, its processing efficiency and complexity of the mechanism cannot be compared to diamond lathes. In the late 1980s, the United States invested huge amounts of money and a large amount of manpower through the “Laser Nuclear Fusion Project†of the Ministry of Energy and the “Advanced Manufacturing Technology Development Plan†of the Army, Navy and Air Force. Micro-inch ultra-precision machining of large parts. The Large Optics Diamond Turning Machine (LODTM) developed by LLL National Laboratory in the United States has become a classic in the history of ultra-precision machining. This is a vertical lathe with a maximum diameter of 1.625 m and a positioning accuracy of 28 nm. With the online error compensation capability, it can be processed with a length of more than 1 m and a straightness error of only ±25 nm.
(3) The mature period of private industrial application since the 1990s. Since 1990, the demand for ultra-precision processing machines has increased dramatically due to the booming industries such as automotive, energy, medical equipment, information, optoelectronics and communications. Applications in the industry include aspherical optical lenses, Fresnel lenses, and ultra-precision molds. , disk drive heads, disk substrate processing, semiconductor wafer cutting, etc. During this period, related technologies of ultra-precision processing equipment, such as controllers, laser interferometers, air bearing precision spindles, air bearing guides, hydraulic bearing guides, and friction-driven feed shafts have gradually matured, and ultra-precision machining equipment has become Production machinery and equipment common in the industry, many companies, even small companies have also introduced mass production equipment. In addition, the accuracy of the equipment is gradually approaching the nanometer level, the processing stroke becomes larger, and the processing application is gradually widened. In addition to the diamond lathe and ultra-precision grinding, ultra-precision five-axis milling and flying cutting technology have also been developed and can be Processing of non-axisymmetric aspherical optical lenses.
At present, the world's ultra-precision processing powers are dominated by Europe, America and Japan, but the research focus of the two is not the same. Europe and the United States have paid great attention to energy or space development, especially in the United States. For decades, they have invested heavily in research on the processing of large-diameter mirrors for large-scale ultraviolet and X-ray telescopes. For example, the Space Development Program promoted by the US Space Agency (NASA) aims to produce mirrors of more than 1 m in order to detect shortwaves (0.1 to 30 nm) such as X-rays. Due to the high energy density of the X-ray, the surface roughness of the mirror must be increased to an angstrom level to increase the reflectivity. At present, the material of such a mirror is silicon carbide with good mass and good thermal conductivity, but the hardness of silicon carbide is very high, and ultra-precision grinding processing is required. Japan's research on ultra-precision machining technology started relatively late in the United States and Britain, but it is the fastest growing country in the world. Most of the applications for ultra-precision machining in Japan are civilian products, including office automation equipment, video equipment, precision measuring instruments, medical equipment and artificial organs. Japan has advantages in ultra-precision processing technology for small, ultra-small electronic and optical components in sound, light, image, and office equipment, even surpassing the United States. Japan's ultra-precision machining began with diamond cutting of aluminum and copper hubs, and then concentrated on mass production of computer hard disk magnetic sheets, followed by rapid diamond cutting of polygon mirrors for laser printers and the like, followed by optical components such as aspherical lenses. Ultra-precision cutting. An aspherical lens used in the Eastman Kodak digital camera, which was launched in 1982, has attracted widespread attention in the Japanese industry. Because an aspheric lens can replace at least three spherical lenses, the optical imaging system is compact and lightweight. Widely used in cameras, video recorders, industrial television, robot vision, CD, VCD, DVD, projectors and other optoelectronic products. Therefore, the precision forming of aspherical lenses has become a research hotspot in the Japanese optical industry.
Despite the changes of the times, the ultra-precision machining technology is constantly updated, the machining accuracy is continuously improved, and the research focus between countries is different, but the factors that promote the development of ultra-precision machining are essentially the same. These factors can be summarized as follows.
(1) The pursuit of high quality products. In order to achieve higher disk storage density or better optical performance of the lens, it is necessary to obtain a surface having a lower roughness. In order for the function of the electronic component to function properly, it is required that the processed surface does not remain in the processed layer. According to the technical requirements of the American Society for Microelectronics (SIA), the head of the next-generation computer hard disk requires a surface roughness Ra ≤ 0.2 nm, the disk requires a surface scratch depth h ≤ 1 nm, and the surface roughness Ra ≤ 0.1 nm. In 1983, TANIGUCHI summarized the processing precision of each period and predicted its development trend. Based on this, BYRNE et al. described the development of processing precision in the 1940s, as shown in Figure 1. Figure 2 shows the machining accuracy available for various machining methods in 2003. Among them, microfabrication can realize processing with a feature size of 1 μm and a surface roughness of 5 nm.
(2) The pursuit of product miniaturization. Along with the improvement in machining accuracy, the size of engineering components is reduced. Figure 3 depicts the quality changes of the ABS system on the vehicle during each period. From 1989 to 2001, it was reduced from 6.2 kg to 1.8 kg. The high integration of electronic circuits requires lowering the surface roughness of silicon wafers, improving the precision of lenses for circuit exposure, and the motion accuracy of semiconductor manufacturing equipment. The miniaturization of components means that the ratio of surface area to volume is increasing, and the surface quality and integrity of the workpiece is becoming more and more important.
(3) The pursuit of high reliability of products. For parts such as bearings that are subjected to relative movement while being loaded, reducing the surface roughness can improve the wear resistance of the parts, improve their working stability, and extend the service life. At present, the surface roughness of Si3N4 ceramic balls used in high-speed high-precision bearings is required to reach several nanometers. The chemically affected layer of the processing metamorphic layer is active and susceptible to corrosion. Therefore, from the viewpoint of improving the corrosion resistance of the part, the metamorphic layer produced by the processing is required to be as small as possible.
(4) The pursuit of high performance products. The improvement of the motion accuracy of the mechanism is beneficial to slow the fluctuation of mechanical properties, reduce vibration and noise. For machines requiring high sealing such as internal combustion engines, good surface roughness reduces leakage and reduces losses. After the Second World War, the aerospace industry required some parts to work in a high temperature environment. Therefore, the use of difficult-to-machine materials such as titanium alloys and ceramics has raised new issues for ultra-precision machining.
The above four aspects are interrelated and jointly promote the development of ultra-precision processing technology. The internationally renowned ultra-precision processing research units and enterprises mainly include LLL Laboratory and Moore Company of the United States, Granfield and Tayler of the United Kingdom, Zeiss and Kugler of Germany, Toshiba Machine of Japan, Toyota Machine and Fujitsu Company. China began to study ultra-precision machining technology in the early 1980s. The main research units include Beijing Machine Tool Research Institute, Tsinghua University, Harbin Institute of Technology, Changchun Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Dalian University of Technology and Zhejiang University of Technology. Wait.
2 Ultra-precision machining materials
In order to meet the quality requirements of high precision, high reliability, high stability, many metals and their alloys, ceramic materials, optical glass, etc. need to be ultra-precision processed to achieve specific shape, precision and surface integrity. Here we introduce the advanced ceramic materials.
Advanced ceramic materials have become one of the foundations for the development of high-precision machinery, aerospace, military, and optoelectronic information. Advanced ceramics can be roughly classified into functional ceramics and structural ceramics depending on their performance and application range. Functional ceramics mainly refer to ceramics that utilize the direct or coupled effects of electrical, optical, magnetic, chemical or biological aspects of materials to achieve specific functions. They are widely used in electronics, communications, computer, laser and aerospace technologies. Structural ceramic materials have excellent high temperature and wear resistance, and have shown broad application prospects as new materials for high performance mechanical structural parts. Table 1 lists some typical advanced ceramic materials and their uses.
Table 2 shows some of the physical properties of ductile metal materials and brittle advanced ceramic materials. Table 3 shows the physical properties of several advanced ceramic materials. Most advanced ceramic materials are covalent ion bond compounds, with low crystal structure symmetry and few dislocations, resulting in high hardness and brittleness. Silicon nitride, silicon carbide and sapphire are second only to diamond and CBN, and are recognized as typical hard and brittle materials. The difference in physical properties between advanced ceramic materials and metal materials determines the difference in the removal mechanism of the two materials. Advanced ceramic materials are prone to cracks and other surface and subsurface damage during processing, which adversely affect the device's performance and working life.
3, ultra-precision processing technology
3.1 ultra-precision cutting
Ultra-precision cutting begins with SPDT technology, which is supported by air bearing spindles, pneumatic slides, high rigidity, high precision tools, feedback control and ambient temperature control for nanometer surface roughness. The tool used is a large piece of diamond single crystal with a very small cutting edge radius (approximately 20 nm). First used for the processing of copper planar and aspheric optical components. Subsequently, the processing materials were extended to plexiglass, plastic products (such as plastic lenses for cameras, contact lens lenses, etc.), ceramics and composite materials. Ultra-precision cutting technology has also expanded from single-point diamond cutting to multi-point diamond milling.
Because diamond tools cause severe wear when cutting steel, some studies have tried to improve this problem using single crystal CBN, ultra-fine grain hard metal, ceramic tools, but the research results have not yet reached the stage of commercialization. The future trend is to use coating technology to improve the wear of diamond tools in the process of hardening steel. In addition, the processing of tiny parts such as MEMS components requires small tools. Currently, the size of small tools can reach 50-100 μm. However, if the machining geometry is sub-micron or even nano-scale, the tool diameter must be reduced. The trend is to use nanomaterials such as carbon nanotubes to make turning tools or milling cutters with ultra-small tool diameters. In summary, the issue of tool materials and micro-tools will be an important research topic in the future of ultra-precision machining.
3.2 Ultra-precision grinding
In the early stage of ultra-precision machining, the grinding method was neglected because the randomness of the radial cutting edge height and the irregularity of the wear in the grinding wheel limit the improvement of the grinding precision. With the development of superabrasive grinding wheel and grinding wheel dressing technology, ultra-precision grinding technology has gradually formed and developed rapidly.
(1) Super abrasive abrasive wheel. Superabrasive grinding wheels are grinding wheels made of diamond or CBN abrasives. Diamond grinding wheel is suitable for grinding hard and brittle non-ferrous metals and hard alloys, optical glass, ceramics, gemstones and other high-hardness, high-brittle non-metallic materials. CBN grinding wheels are suitable for grinding hardened steel, heat-resistant alloys and high hardness. The high toughness of the metal material, which complements each other, covers almost all of the material being processed. The types and characteristics of superabrasive grinding wheels are shown in Table 4.
The metal bond super-abrasive grinding wheel has high hardness, high strength, strong shape retention ability and good wear resistance, and is often used for precision and ultra-precision grinding and forming grinding. The outstanding problem encountered in the actual use of the multi-layer metal bond super-hard grinding wheel is that the abrasive holding power is low and easy to fall off; the abrasive grain is difficult to be bladed, and the exposedness after the blade is difficult to maintain; the abrasive distribution is random. In view of the problem that the abrasive grain holding power is weak, the active metal is plated on the surface of the abrasive grain, and the chemical reaction and diffusion of the active metal with the abrasive and the binder enhance the holding force of the bonding agent on the abrasive, so that the ruthenium-plated grinding wheel is born. In order to solve the problem that the abrasive grains are difficult to form, the porous structure is introduced into the embryo body to produce a porous metal bond grinding wheel. Electroplating and high-temperature brazing wheels have improved in all three respects. These new superabrasive grinding wheels were all introduced in the 1990s.
Although the above research progress has been made in the production of superabrasive grinding wheels, the active elements in the ruthenium-plated grinding wheel are mainly combined with the abrasive grains by a pure solid or semi-solid reaction, and the bonding strength cannot be compared with the high-temperature strontium grinding wheel. However, the single-layer abrasive of the high-temperature tantalum grinding wheel is no longer supplemented by the subsequent abrasive, although its service life is close to that of the multi-layer abrasive, but it is limited. Although the porous metal bond diamond grinding wheel has the characteristics of easy to trim ceramic-bonded super-abrasive grinding wheel, it is at the expense of bonding strength. To this end, Xu Hongjun and other proposals put forward the idea of ​​developing multi-layered brazing super-abrasive grinding wheels, which combines the high holding power of abrasive grains, the preferential arrangement of abrasive grains and pores, and the high degree of dew of abrasive grains.
(2) Superhard abrasive wheel dressing technology.
The super-hard abrasive wheel has excellent wear resistance and does not require frequent dressing, but it is difficult to trim after initial installation and use of blunt. The traditional dressing method often removes the abrasive grains by shearing and pressing to achieve the purpose of dressing, the dressing process is difficult to control, the dressing precision is low, and the grinding wheel loss is large. To this end, domestic and foreign scholars have also proposed a variety of dressing methods, such as Electro in-process dressing (ELID), Electrochemical in-process controlled dressing (ECD), dry ECD, contact Electro-contact discharge dressing (ECDD), electro-chemical dis-charge machining (ECDM), laser-assisted truing and dressing, water-jet in- Process dressing), ultrasonic dressing, and the like. Among them, ELID technology is the most typical and the application is the most mature. The technology was proposed in 1990 by Dr. Omori Mori of the Institute of Physical Chemistry of Japan and Professor Nakagawa of the University of Tokyo. The basic principle of ELID grinding is the in-line fine dressing of the metal bond grinding wheel by electrolysis during the grinding process, so that the abrasive grain is always processed under the condition of sharp micro edge. The number of micro-blades is large and has the same height, and the grinding marks are fine, so that extremely high machining accuracy is obtained while maintaining high efficiency. They processed silicon wafers with a 4 μm diamond wheel to obtain Rmax 48 nm, Ra4 nm surfaces. The surface of Rmax 8.92 nm and Ra 1.21 nm was obtained by submicron particle size diamond grinding wheel. In 1995, Omori and Chuan Weixiong conducted further research on ELID. The single crystal silicon was polished by ELID with #3 000 000 cast iron-based diamond grinding wheel. The surface roughness after processing reached Rmax 2.34 nm and Ra 0.329 nm.
Scholars from various countries have studied ELID processing of various materials such as Al2O3, Si3N4, Zr O2, SiC, Mn-Zn ferrite, single crystal silicon, optical glass and cermet, including removal mechanism, grinding force and grinding heat. Basic rules such as surface quality, as well as key technologies such as grinding performance of grinding wheels, wheel wear and dressing processes, and developed into a variety of products for many industrial sectors. However, ultra-precision grinding removes the material by forced cutting of the abrasive grains, inevitably leaving a process damage layer on the machined surface. Dasen and Chuan Weixiong processed the silicon wafer and glass with a 40000# diamond wheel to obtain a surface roughness of Ra2.8 nm, but with a surface damage layer of about 1 μm. Liu Shimin et al. studied the thickness and structure of the surface metamorphic layer of two kinds of single crystal silicon wafer grinding samples made by ELID grinding technology by using the scanning electron microscope's selected area electronic channel pattern technology. It was found that the surface roughness of the two single crystal silicon wafer samples was rough. The degrees are 9.5 nm and 22.5 nm, and the thickness of the metamorphic layer is 2.8 μm and 4.8 μm, respectively. In addition, ultra-precision grinding requires high precision and rigidity of the machine. High-speed rotation of the grinding wheel shaft must use expensive bearings, and some degree of vibration is always unavoidable. During the grinding process, the grinding wheel needs to be continuously trimmed to keep the sharpness of the abrasive grains, prevent the grinding debris from clogging the surface of the grinding wheel, and the space of the chip and its retention become the main problem of making the ultrafine abrasive wheel; in addition, grinding In the process, the workpiece and the grinding wheel are mainly in line contact mode, and the processing has a unidirectional property, and it is difficult to ensure the uniformity of the processing surface; the non-magnetic magnetic workpiece is difficult to clamp. These problems limit the surface quality that can be obtained by grinding.
(3) Honing. In the 1980s, flat honing (or fine grinding) was used, which used a grinding-like motion method with a grinding wheel speed of 1/30 to 1/60 of the speed of a conventional grinding wheel. Due to the use of surface contact, the number of abrasive particles involved in grinding increases, the vertical load of each abrasive grain is only 1/50 to 1/100 of the grinding condition, and the heat per unit time of a single average cutting edge is conventional. Grinding is about 1/1 500 to 1/3 000, and the resulting thermal metamorphic layer is small. Due to the small depth of the abrasive grain, the resulting deteriorated layer and residual stress are also small. In addition, in the plane honing process, a batch of workpieces can be processed at the same time; the direction of the cutting force acting on the abrasive grains often changes, so that the probability of breakage of the abrasive grains increases, and the self-twisting effect is remarkable. Therefore, from the point of obtaining surface roughness superior to the grinding process, it has higher efficiency than grinding, and the accuracy of the machine tool is not high. The use of flat honing technology to process advanced ceramic materials has now partially replaced grinding. High-speed grinding of flat fixed abrasives using diamond pellets is based on this principle and has been widely used in the planar processing of ceramics, glass, metals and other materials. However, the use of abrasive grains to force the surface of the workpiece to be finished is limited, and the surface quality that can be obtained is limited.
3.3 Ultra-precision grinding and polishing
Grinding and polishing are the oldest processing methods, and they have always been the most important processing methods for ultra-precision machining. Usually, the grinding is a sub-finishing process, and the flatness is reduced to a few micrometers or less, and the damaged layer produced by the preceding process (usually grinding) is removed. Polishing is currently the main final processing method, the purpose is to reduce the surface roughness and remove the damaged layer formed by grinding to obtain a smooth, damage-free processing surface. The amount of material removed during polishing is very small, about 5 μm. So far, many scholars have proposed a variety of polishing methods, among which the most widely used, the most mature technology is chemical mechanical polishing (CMP) technology.
CMP was developed by IBM in the mid-1980s, first for the production of 64-bit RAM and then for the entire semiconductor industry. YASUNAGA et al. polished sapphire with Si O2, polished single crystal silicon with BaCO3, CeO2 and CaCO3, polished quartz with Fe2O3 and MgO, and obtained a smooth and damage-free surface (surface roughness close to 1 nm). The chemical mechanical polishing was first proposed and verified. the concept of. CMP processing realizes the micro-removal of the workpiece material through the mechanical and chemical interaction between the abrasive-work-machining environment, and can obtain the ultra-smooth, less/no damage processing surface; the processing trajectory is multi-directional, which is beneficial to the surface processing. Uniform consistency; the process follows the "evolution" principle and does not require high precision processing equipment. Because CMP technology can provide the full planarization required for VLSI manufacturing (which is unmatched by other technologies), it has become one of the leading technologies in the semiconductor industry and is expanding its application fields.
Although CMP technology is considered to be an effective method for obtaining an ultra-smooth, damage-free surface, a surface roughness of 0.1 nm and a very small surface damage layer can be obtained. (In 2000, OGITA used SC1 to clean the silicon wafer on the CMP and found the thickness of the surface damage layer. It is 21 nm), but it also has certain limitations, mainly reflected in the processing accuracy is sensitive to the difference in abrasive grain size. Under ideal conditions, the abrasive grain size between the workpiece and the tool is uniform and the load on the abrasive particles is equal (Figure 4a). When there are hard large particles in the processing zone (abrasive agglomeration or workpiece grinding debris) or entering (large particle dust in the external environment), if the grinding tool is rigid, the processing load is borne by a small amount of large particles, resulting in large particles. The depth of cut of the workpiece is increased to cause damage such as scratches and pits, or large particles are broken under load, but damage is often formed on the surface of the workpiece before crushing (Fig. 4b); for this reason, an elastic polishing pad is usually used ( Asphalt, polyurethane and other materials) to alleviate the negative effects of large particles on the surface of the workpiece, but due to the increased elastic deformation of the position where the polishing pad is in contact with the large particles, the pressure on the large particles increases, which still causes the surface of the workpiece to be scratched. Traces and other forms of damage (Figure 4c). At present, it is only possible to avoid the damage of the hard large particles to the processing surface by improving the purification degree of the processing environment and the consistency of the abrasive grain size, but it is expensive and cannot completely avoid the invasion of large particles. Surface scratches caused by hard large particles cause a large number of workpieces to be repaired or scrapped, which seriously hinders the improvement of overall processing efficiency. How to effectively avoid damage caused by hard large particles has become an urgent problem to be solved in the polishing process. In addition, the material removal is mainly based on the three-body wear mechanism. The abrasive particles mainly remove the material in a rolling manner. The amount of abrasive particles involved in material removal per unit time is small, the material removal rate is low, and the chemical composition and the abrasive particles are harmful. Environment and high processing costs.
In addition to CMP technology, the classic ultra-precision grinding and polishing methods are as follows.
(1) Elastic emission machine (EEM). Osaka University of Japan TSUWA et al. studied the feasibility of removing materials at the atomic level on the surface of the workpiece, and established the theory of elastic emission processing. The processing principle and production equipment are shown in Figures 5 and 6, respectively. The EEM technology uses the immersion working mode to drive the abrasive with a particle size of several tens of nanometers in the polishing liquid by using a polyurethane ball rotating at a high speed on the surface of the workpiece, and impact the surface of the workpiece with the incident angle as small as possible, through the chemistry between the abrasive particles and the workpiece. The function of removing the workpiece material, the surface layer of the workpiece is not plastically deformed, and no defects such as lattice transposition are generated, which is extremely advantageous for processing functional crystal materials. TSUWA uses a polyurethane ball as a tool to elastically eject single crystal silicon with Zr O2 micropowder with a surface roughness of 0.5 nm.
(2) Dynamic pressure floating polishing. WATANABE et al. developed a dynamic pressure float polishing technique using the principle of dynamic pressure bearings, as shown in Figure 7. By making a plurality of inclined planes along the circumferential direction of the polishing disc, the workpiece is floated on the surface of the polishing disc by the hydraulic pressure generated when the polishing disc is rotated, and the workpiece is polished by the polishing particles in the floating gap. Since there is no frictional heat and abrasive wear, the standard surface does not change, so the precise workpiece surface can be obtained repeatedly. Using this polishing method to process a silicon wafer with a diameter of 75 mm, a flatness of 0.3 μm and a surface roughness of 1 nm are obtained.
(3) Float polishing. In 1977, researchers such as NAMBA in Japan proposed a float polishing process for processing polished head materials. The principle is shown in Figure 8. The process uses a highly flat plane with a tin-polished disc with concentric circles or spiral grooves, which covers the entire surface of the polishing disc, allowing the polishing disc and the workpiece to rotate at high speed, and the polishing fluid is dynamically pressed between the two. The liquid state forms a liquid film, and the abrasive in the liquid film impacts the surface of the workpiece at a high speed to remove the material. NAMBA and other SiO2 colloidal, CeO2 and Al2O3 polisher sapphire (001) surfaces were float polished with a surface roughness of less than 1 nm. Compared with other polishing methods, the polished workpiece edge geometry is regular, the sub-surface layer is not damaged, the surface residual stress caused by polishing is extremely small, and the crystal surface has a perfect crystal lattice. Float polishing is similar to EEM polishing, except that the float polishing uses a hard tin plate as the grinding tool, while the EEM method uses a polyurethane rubber wheel as the grinding tool.
(4) Low temperature polishing. Low-temperature polishing refers to polishing with a polishing liquid that has condensed into a solid state in a low-temperature environment. Han Rongjiu etc. freezes the colloidal SiO2 into a solid film and then maintains the temperature between –50 and –30 °C. The K9 glass is processed to obtain a surface roughness of Ra 0.4 nm. WU et al. combined the low-temperature polishing method with the non-abrasive polishing technology, and proposed a non-abrasive low-temperature polishing method, that is, solid ice with deionized water at a low temperature as a polishing tool. MaQ glass can be processed to obtain a surface roughness of Ra0.48 nm (the surface roughness of the workpiece before processing is Ra1.3 nm). Analysis of the water produced after processing, no solid glass fragments were found, and the material was judged to be removed by hydrolysis, thereby effectively preventing the occurrence of defects such as micro-scratches. After polishing for 40 h, the mass change of the workpiece was not measured with an electronic balance with an accuracy of 0.01 g. However, due to the extremely high cost of maintaining a low temperature, vacuum environment, applications are limited.
(5) Magnetic field assisted polishing. Magnetic field assisted polishing mainly includes magnetic abrasive finishing (MAF), magnetic floating polishing (MPF) and magnetorheological finishing (MRF).
The concept of magnetic grinding was first proposed by former Soviet engineer Kagolow in 1938. During processing, the magnetic abrasive particles (microparticles that must have both magnetizable and abrasive properties) form a "magnetic brush" under the action of a magnetic field, and the "magnetic brush" and the workpiece are generated by the relative movement of the magnetic pole and the workpiece. Interference with friction to complete processing. The processing pressure can be controlled by a magnetic field. FOX et al. used a 0.1 μm diamond micropowder to magnetically grind the stainless steel roller to obtain a Ra10 nm surface. The magnetic abrasive grain processing has almost no restrictions on the geometric shape of the workpiece, and the precision of the equipment is not high. In particular, the abrasive grain is not in rigid contact with the surface of the workpiece, so even if there are a few large abrasive grains or the surface of the workpiece occasionally appears unevenly hard. At the point, the surface of the workpiece is not scratched due to a sudden change in the cutting resistance. However, in the MAF research papers published in the past, almost 90% of the experiments were made of sintered magnetic abrasives because of the complicated sintering process, high cost and limited application.
Magnetic floating polishing was developed by TANI et al., and has been continuously developed by many scholars such as UMEHARA, CHILDS, and KATO. The device is shown in Figure 9. When the non-magnetic abrasive is mixed into the magnetic fluid and placed in a magnetic field, the magnetic fluid is attracted to the side of the high magnetic field due to the action of the ferromagnetic particles in the magnetic fluid, and the non-magnetic abrasive grains are pushed to the opposite direction of the movement of the magnetic fluid. The abrasive particles on one side of the magnetic field are pressed against the rotating workpiece by the buoyancy of the magnetic fluid for polishing. JIANG et al. used the magnetic floating polishing method to process Si3N4 ceramic balls (Ce O2, 5 μm), and obtained the surface precision of Ra 4 nm and Rz 40 nm.
Magnetorheological processing was proposed by KORDONSKY et al. in the early 1990s. They combine electromagnetism and fluid dynamics theory, using magnetorheological fluids (suspensions consisting of magnetic particles, base fluids, and stabilizers) in the magnetic field. The rheological properties in the polishing of the optical glass. The rheological properties of the magnetorheological fluid can be controlled by the adjustment of the applied magnetic field strength. The magnetorheological processing device is shown in Figure 10. The magnetorheological fluid is sprayed by a nozzle on a rotating polishing wheel, and the magnetic pole is placed under the polishing wheel to form a high gradient magnetic field near the narrow gap formed by the workpiece and the polishing wheel. When the magnetorheological fluid on the polishing wheel is transferred to the vicinity of the small gap formed by the workpiece and the polishing wheel, the high gradient magnetic field causes it to coagulate and harden, becoming a viscoplastic Bingham medium. When a Bingham medium having a high moving speed passes through a small gap, a large shear force is generated in a region where the surface of the workpiece comes into contact with it, so that the surface material of the workpiece is removed. During the polishing process, selective removal of the surface of the workpiece can be achieved by controlling the sweep rate (or residence time) of the magnetorheological fluid in the workpiece. 1997 å¹´ JACOBS ç‰å¯¹çº¢å¤–ææ–™ BK7ã€CaF2ã€LiF ç‰è¿›è¡Œç£æµå˜æŠ›å…‰ï¼ŒèŽ·å¾—表é¢ç²—糙度å°äºŽ 5 nm的光滑表é¢ã€‚ 2006 å¹´å™å¸Œå¨ç‰ç”¨ç£æµå˜æŠ›å…‰åŠ 工了R41.3 mmã€å£å¾„ 20 mm çš„ K9 å…‰å¦çŽ»ç’ƒçƒé¢å·¥ä»¶,获得了表é¢ç²—糙度 8.441 nmã€é¢å½¢ç²¾åº¦57.911 nm PV 的表é¢ã€‚
(6) 气囊å¼æŠ›å…‰ã€‚气囊å¼æŠ›å…‰æŠ€æœ¯æ˜¯ 2000 年伦敦å¦é™¢å¤§å¦å…‰å¦ç§‘å¦å®žéªŒå®¤å’Œ Zeeko 有é™å…¬å¸è”åˆæ出的。抛光工具外é¢åŒ…有磨料薄膜层(如èšæ°¨é…¯æŠ›å…‰åž«ã€æŠ›å…‰å¸ƒç‰)的胶皮气囊。抛光工作时,工具气囊旋转形æˆæŠ›å…‰è¿åŠ¨ï¼Œå·¥ä»¶å¯¹æ°”囊抛光工具作相对的进给è¿åŠ¨ï¼Œä½¿å·¥ä»¶çš„全部表é¢éƒ½è¢«èƒ½æŠ›å…‰åŠ 工。工具气囊åŒæ—¶è¿˜ä½œæ‘†åŠ¨(摆动ä¸å¿ƒä¸ºæ°”囊曲é¢çš„曲率ä¸å¿ƒ),使磨料薄膜层å‡åŒ€ç£¨æŸã€‚由于工具气囊具有弹性,å¯ä»¥è‡ªåŠ¨é€‚应工件的曲é¢å½¢çŠ¶ï¼Œæ•…åŒä¸€å·¥å…·å¯ç”¨äºŽæŠ›å…‰ä¸åŒå¤–形的曲é¢ã€‚该方法适于大型自由曲é¢çš„è¶…ç²¾å¯†åŠ å·¥ã€‚
(7) 应力盘抛光。为实现大型éžçƒé¢å…ƒä»¶çš„è¶…ç²¾å¯†åŠ å·¥ï¼Œè¯žç”Ÿäº†åº”åŠ›ç›˜æŠ›å…‰æ–¹æ³•ã€‚è¯¥æ–¹æ³•é‡‡ç”¨å¤§å°ºå¯¸åˆšæ€§ç›˜ä½œä¸ºåŸºç›˜ï¼Œåœ¨å‘¨è¾¹å¯å˜åº”力的作用下,盘的é¢å½¢å¯ä»¥å®žæ—¶åœ°å˜å½¢æˆæ‰€éœ€è¦çš„é¢å½¢ï¼Œä»¥é€‚é…éžçƒé¢çš„ä¸åŒä½ç½®ä¸Šçš„å»åˆç ”磨。应力盘抛光技术具有优先去除表é¢æœ€é«˜ç‚¹æˆ–部ä½çš„特点,具有平滑ä¸é«˜é¢‘差的趋势,å¯ä»¥å¾ˆå¥½åœ°æŽ§åˆ¶ä¸é«˜é¢‘差的出现ã€æœ‰æ•ˆåœ°æé«˜åŠ å·¥æ•ˆçŽ‡ã€‚2002 å¹´ MARTIN ç‰ç”¨åº”力盘抛光技术对 Magellan 望远镜 6.5 mf/1.25 主镜和Large Binocular 望远镜 8.4 mf/1.14 主镜进行了抛光,这些大型镜片都是éžçƒé¢é•œï¼ŒåŠ å·¥åŽå½¢çŠ¶è¯¯å·®ä¸º0.01%,表é¢ç²—糙度为 20 nm。
(8) 电解抛光。电解抛光åˆç§°ç”µåŒ–å¦æŠ›å…‰ï¼Œèµ·æºäºŽ 20 世纪åˆã€‚1930 年法国电è¯å…¬å¸Jacquet 首次æå‡ºç”µè§£æŠ›å…‰æŠ€æœ¯ï¼Œå¹¶è¿›è¡Œäº†ç³»ç»Ÿç ”ç©¶ã€‚ç›®å‰ï¼Œè§£é‡Šç”µè§£æŠ›å…‰è¿‡ç¨‹æ¯”较åˆç†çš„ç†è®ºæ˜¯è–„膜ç†è®ºã€‚薄膜ç†è®ºè®¤ä¸ºï¼Œç”µè§£æŠ›å…‰æ—¶ï¼Œé è¿‘é‡‘å±žè¯•æ ·é˜³æžè¡¨é¢çš„ç”µè§£æ¶²ï¼Œåœ¨è¯•æ ·ä¸Šéšç€è¡¨é¢å‡¹å‡¸é«˜ä½Žä¸å¹³å½¢æˆä¸€å±‚薄厚ä¸å‡åŒ€çš„粘性薄膜。由于电解液æ…æ‹ŒæµåŠ¨ï¼Œåœ¨é è¿‘è¯•æ ·è¡¨é¢å‡¹é™·çš„地方,扩散æµåŠ¨å¾—è¾ƒæ…¢ï¼Œå› è€Œå½¢æˆçš„è†œè¾ƒåŽšï¼Œè€Œåœ¨å‡¸èµ·çš„åœ°æ–¹è–„è†œè¾ƒè–„ã€‚ç”±äºŽè¯•æ ·è¡¨é¢å„处的电æµå¯†åº¦ç›¸å·®å¾ˆå¤šï¼Œå‡¸èµ·é¡¶å³°åœ°æ–¹ç”µæµå¯†åº¦å¾ˆå¤§ï¼Œé‡‘属快速地溶解于电解液ä¸ï¼Œè€Œå‡¹é™·éƒ¨åˆ†é‡‘属则溶解慢,结果使得粗糙的表é¢å˜å¾—平整从而达到抛光的目的。2003 å¹´ HUANG ç‰å¯¹é«˜é€Ÿé’¢è¿›è¡Œç”µè§£æŠ›å…‰ï¼ŒèŽ·å¾— Ra30~50 nm 的表é¢ã€‚
(9) 离åæŸæŠ›å…‰ã€‚离åæŸæŠ›å…‰æ˜¯æŠŠä¸æ€§ç¦»å在电场ä¸åŠ 速,撞击工件表é¢çš„原å或分å,使其逸出表é¢ä»Žè€Œå°†æ料去除(图 11)ã€‚ç”±äºŽè¢«åŠ å·¥æ料以原å或分å为å•ä½åŽ»é™¤ï¼Œå¯èŽ·å¾—纳米级高质é‡åŠ 工表é¢ã€‚LIç‰ç”¨æ°Ÿç¦»åæŸå¯¹ CMP åŽçš„ 50 mmGaSbå¤–å»¶ç‰‡è¿›è¡Œè¶…ç²¾åŠ å·¥ï¼Œä½¿å…¶è¡¨é¢ç²—糙度由 0.7 nm é™ä½Žåˆ° 0.18 nm。离åæŸæŠ›å…‰å¯åŠ 工的ææ–™èŒƒå›´è¾ƒå¹¿ï¼Œå¯¹å·¥ä»¶å°ºå¯¸æ²¡æœ‰ä¸¥æ ¼æŽ§åˆ¶ï¼Œå¹¶ä¸”å¯åŠ å·¥çƒé¢ã€éžçƒé¢å’Œéžå¯¹ç§°é¢å½¢ã€‚
(10) ç‰ ç¦» å 体 è¾… 助 抛 å…‰ (Plasma-assisted chemical ething,PACE)。ç‰ç¦»å体辅助抛光åˆç§°åŒ–å¦ è’¸ å‘ åŠ å·¥ (chemical vaporization machining ,CVM),是在真空环境下进行,其设备如图 12 所示。将化å¦æ°”体(通常为å¤ç´ 类气体,如 CFã€Cl2ç‰)æ¿€å‘æˆæ´»æ€§ç‰ç¦»åä½“ï¼Œä¸ŽåŠ å·¥é¢äº§ç”ŸåŒ–å¦å应,生æˆæŒ¥å‘性物质从而达到æ料去除的目的。这ç§åŠ 工方法实用化的一ç§å°±æ˜¯ç‰ç¦»åè…蚀。
PACEåŠ å·¥å…·æœ‰æŠ›å…‰æ•ˆçŽ‡é«˜ï¼Œå·¥ä½œä¸å—机械压力,没有机械å˜å½¢ï¼ŒåŠ 工表é¢æ— 亚表é¢æŸä¼¤ã€æ— æ±¡æŸ“ï¼ŒåŠ å·¥çƒé¢å’Œéžçƒé¢éš¾æ˜“相当ç‰ä¼˜ç‚¹ã€‚ç›®å‰Perkin-Elmer å…¬å¸ç”¨è¯¥æŠ€æœ¯å·²åœ¨Ï† 0.5 m~1.0 m çš„éžçƒé¢ä¸ŠåŠ 工出é¢å½¢ç²¾åº¦å°äºŽ 1/50λ,表é¢ç²—糙度å°äºŽ 0.5 nm 的表é¢ã€‚
(11) 激光抛光。激光抛光技术是利用激光与æ料表é¢ç›¸äº’ä½œç”¨è¿›è¡ŒåŠ å·¥ï¼Œå®ƒéµå¾ªæ¿€å…‰ä¸Žæ料作用的普é规律。激光与æ料间的作用方å¼æœ‰çƒä½œç”¨å’Œå…‰åŒ–å¦ä½œç”¨ï¼Œå¯æŠŠæ¿€å…‰æŠ›å…‰åˆ†ä¸ºçƒæŠ›å…‰å’Œå†·æŠ›å…‰ã€‚çƒæŠ›å…‰æ˜¯åˆ©ç”¨æ¿€å…‰çš„çƒæ•ˆåº”,通过熔化ã€è’¸å‘ç‰è¿‡ç¨‹åŽ»é™¤ææ–™ã€‚å› æ¤åªè¦æ料的çƒç‰©ç†æ€§èƒ½å¥½ï¼Œéƒ½å¯ä»¥ç”¨å®ƒæ¥è¿›è¡ŒæŠ›å…‰ï¼Œä½†ç”±äºŽæ¸©åº¦æ¢¯åº¦å¤§è€Œäº§ç”Ÿçš„çƒåº”åŠ›å¤§ï¼Œæ˜“äº§ç”Ÿè£‚çº¹ï¼Œå› æ¤çƒæŠ›å…‰çš„效果ä¸æ˜¯å¾ˆå¥½ã€‚冷抛光是利用ææ–™å¸æ”¶å…‰ååŽï¼Œè¡¨å±‚æ料的化å¦é”®è¢«æ‰“æ–æˆ–è€…æ˜¯æ™¶æ ¼ç»“æž„è¢«ç ´å,从而实现æ料的去除。利用光化å¦ä½œç”¨æ—¶ï¼Œçƒæ•ˆåº”å¯ä»¥è¢«å¿½ç•¥ï¼Œå› æ¤çƒåº”力很å°ï¼Œä¸äº§ç”Ÿè£‚纹,也ä¸å½±å“周围æ料,且容易控制æ料的去除é‡ï¼Œç‰¹åˆ«é€‚åˆäºŽç¡¬è„†æ€§ææ–™çš„ç²¾å¯†åŠ å·¥UDREA ç‰åˆ©ç”¨ CO2激光器对光纤的端é¢è¿›è¡ŒæŠ›å…‰ï¼Œå¾—到的 Ra 100 nm 表é¢ç²—糙度。激光抛光是一ç§éžæŽ¥è§¦æŠ›å…‰ï¼Œä¸ä»…能对平é¢è¿›è¡ŒæŠ›å…‰ï¼Œè¿˜èƒ½å¯¹å„ç§æ›²é¢è¿›è¡ŒæŠ›å…‰ã€‚而且对环境的污染å°ï¼Œå¯ä»¥å®žçŽ°å±€éƒ¨æŠ›å…‰ï¼Œç‰¹åˆ«é€‚用于超硬æ料和脆性æ料的精抛,具有良好的å‘展å‰æ™¯ã€‚但目å‰æ¿€å…‰æŠ›å…‰ä½œä¸ºä¸€ç§æ–°æŠ€æœ¯è¿˜å¤„于å‘展阶段,还å˜åœ¨ç€è®¾å¤‡å’ŒåŠ å·¥æˆæœ¬é«˜ã€åŠ 工过程ä¸çš„检测技术和精度控制技术è¦æ±‚比较高ç‰ç¼ºç‚¹ã€‚
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如å‰æ‰€è¿°ï¼Œè¶…精密切削以高刚度ã€é«˜ç²¾åº¦çš„设备为支撑,å¯èŽ·å¾—纳米级表é¢ç²—糙度,具有较高的æ料去除率。但åŒä¸€æ—¶é—´ä»…èƒ½åŠ å·¥ä¸€ä»¶å·¥ä»¶ï¼Œæ•…è€Œç”Ÿäº§æ•ˆçŽ‡å¯èƒ½ä¸åŠå¤šç‰‡åŠ å·¥çš„ç£¨å‰Šæˆ–ç ”ç£¨æŠ›å…‰æŠ€æœ¯ã€‚åŒæ ·è¶…ç²¾å¯†ç ‚è½®ç£¨å‰Šä¹Ÿè¦æ±‚高刚度ã€é«˜ç²¾åº¦çš„设备,ææ–™åŽ»é™¤çŽ‡é«˜ï¼Œä½¿ç”¨è¶…ç»†ç£¨ç²’ç ‚è½®ç”šè‡³å¯ä»¥èŽ·å¾—埃级表é¢ç²—ç³™åº¦ã€‚ä½†è¶…ç»†ç£¨ç²’ç ‚è½®çš„åˆ¶å¤‡åŠå…¶å®¹å±‘空间的ä¿æŒç‰é—®é¢˜å°šæœªæˆç†Ÿã€‚ç”±ç ‚è½®ç£¨å‰Šå‘展而æ¥çš„å¹³é¢ç©ç£¨æŠ€æœ¯é‡‡ç”¨é™ä½Žç ‚轮转速的方法,å‡å°‘ç£¨å‰ŠåŠ å·¥çš„è¡¨é¢æŸä¼¤ï¼Œåˆ©ç”¨å·¥ä»¶ä¸Žç ‚轮的é¢æŽ¥è§¦å½¢å¼å¯ä»¥è¡¥å¿å› 转速é™ä½Žå¸¦æ¥çš„磨削效率的æŸå¤±ã€‚对设备精度è¦æ±‚ä¸é«˜ï¼Œä½†ä¸Žè¶…精密切削ã€ç£¨å‰Šä¸€æ ·ï¼Œé€šè¿‡è¢«åŠ å·¥æ料的强制性去除方å¼å®ŒæˆåŠ 工,é™åˆ¶äº†æ‰€èƒ½èŽ·å¾—的表é¢è´¨é‡ï¼Œä¸å¯é¿å…åœ°åœ¨åŠ å·¥è¡¨é¢ç•™ä¸‹åŠ å·¥æŸä¼¤å±‚。相对于超精密磨削ã€ç©ç£¨ç‰å›ºç€ç£¨ç²’åŠ å·¥ï¼Œåˆ©ç”¨æ¸¸ç¦»ç£¨ç²’è¿›è¡ŒåŠ å·¥çš„è¶…ç²¾å¯†ç ”ç£¨æŠ›å…‰æŠ€æœ¯ï¼Œå¦‚ CMPã€EEM ç‰ï¼Œå¯èŽ·å¾—更高的表é¢è´¨é‡å’Œæ›´å°çš„åŠ å·¥æŸä¼¤å±‚ã€‚ä½†ç”±äºŽåŠ å·¥è¿‡ç¨‹ä¸ç£¨ç²’处于游离状æ€ï¼Œç£¨ç²’对工件的作用是éžå¼ºåˆ¶æ€§çš„,ææ–™åŽ»é™¤çŽ‡æ›´ä½Žã€‚ä¸”åŠ å·¥ç²¾åº¦å’ŒåŠ å·¥æ•ˆçŽ‡å¯¹ç£¨ç²’å°ºå¯¸å·®å¼‚å分æ•æ„Ÿï¼Œç¡¬è´¨å¤§é¢—粒的侵入å¯å¯¼è‡´å¤§é‡å·¥ä»¶è¿”修或报废,在é™ä½ŽåŠ å·¥ç²¾åº¦å’ŒåŠ å·¥æ•ˆçŽ‡åŒæ—¶å¼•èµ·ç”Ÿäº§æˆæœ¬çš„大幅上å‡ã€‚ç£æ€§ç£¨ç²’åŠ å·¥è™½ç„¶é™ä½Žäº†å¯¹ç¡¬è´¨å¤§é¢—ç²’çš„æ•æ„Ÿåº¦ï¼Œä½†ç£æ€§ç£¨ç²’å¤æ‚而昂贵的制备过程é™åˆ¶å…¶å‘展和应用。离åæŸæŠ›å…‰ç‰ä¸ä½¿ç”¨ç£¨ç²’的超精密抛光方法,以原å为å•ä½åŽ»é™¤æ料,å¯èŽ·å¾—æžé«˜çš„表é¢ç²—糙度,但æ料去除率æžä½Žï¼Œé€šå¸¸ä»…用于 CMP ç‰æŠ›å…‰å·¥è‰ºåŽï¼Œä½¿å·¥ä»¶è¡¨é¢è´¨é‡å’ŒæŸä¼¤å±‚进一æ¥æ高。æ¤ç±»æŠ€æœ¯é€šå¸¸éœ€è¦ç‰¹æ®Šçš„设备,è¦æ±‚é«˜ç²¾åº¦çš„æ£€æµ‹æŠ€æœ¯å’ŒæŽ§åˆ¶æŠ€æœ¯ï¼ŒåŠ å·¥æˆæœ¬é«˜ã€‚
ä¸ºå®žçŽ°é«˜æ•ˆç²¾å¯†åŠ å·¥ï¼Œè¯žç”Ÿäº†å°†å›ºç€ç£¨ç²’åŠ å·¥å’Œæ¸¸ç¦»ç£¨ç²’åŠ å·¥è¿›è¡Œæ•´åˆçš„åŠå›ºç€ç£¨ç²’åŠ å·¥æ¦‚å¿µã€‚SHIMADA ç‰æ出了一ç§ä½¿ç”¨åŠå›ºæ€çš„ç£æ€§æŠ›å…‰ä½“(Magnetic compound fluid polishing tool,MPT)è¿›è¡Œè¶…ç²¾å¯†åŠ å·¥çš„æ–¹æ³•ã€‚è¯¥æ–¹æ³•å°†ç£æ€§å¤åˆæµä½“(Magnetic compound fluid,MCF)和磨粒ã€æ¤ç‰©çº¤ç»´å‡åŒ€æ··åˆåŽåœ¨ç£åœºæ¡ä»¶ä¸‹åŽ‹ç¼©åˆ¶å¾— MPT,MPT 在ç£åœºä½œç”¨ä¸‹ä¸ºåŠå›ºæ€ï¼Œä»¥æ¤å¯¹å·¥ä»¶è¿›è¡ŒåŠ 工。他们使用微米级é“粉构æˆçš„ MPT 对 SUS430 ä¸é”ˆé’¢è¿›è¡ŒæŠ›å…‰ï¼ŒèŽ·å¾— Ra15 nm 的表é¢ã€‚ç›®å‰æ¤æ–¹é¢ç ”究尚处于起æ¥é˜¶æ®µã€‚
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