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1 Introduction In 1940, the British Charles and Geoffrey Hwward first solved the leakage problem of chemical pumps with dangerous media. The solution was to use magnetic drive pumps. In the next 30 years, permanent magnet transmission technology progressed very slowly due to magnetic materials. The advent of high-performance neodymium iron boron (NdFeB) permanent magnet materials in 1983 provided key component materials for the rapid development of magnetic drive pumps. In recent years, permanent magnet transmission technology has expanded from pumps to other sealing machinery. The technology has focused on improving the reliability of equipment, research on new materials resistant to media corrosion, fluid technology and the accuracy of manufacturing and assembly. The magnetic pump represents a * * The level of manufacturing technology, industrial development in recent years * * The magnetic pump has made breakthrough progress in terms of efficiency, life, manufacturing cycle, cost, reliability, etc. Permanent magnet transmission technology transmits the power of the prime mover to the internal magnetic components on the working shaft through the external magnetic components on the shaft. The internal and external magnetic components are separated by an isolation cover, so that the working shaft does not need to extend out of the space to be enclosed, eliminating the need for dynamic seals, achieving no sealing and zero leakage. Permanent magnet transmission technology is mainly used in pumps and compressors, mixers and valves in the chemical industry, petrochemical industry, medicine, and food industry. At present, the traditional mechanical seals used extensively in my country's fluid machinery have gradually been replaced by permanent magnet drives in these foreign departments. 2 Expansion of application fields and improvement of technical performance 2.1 Magnetic transmission is the most effective and safe solution in the field of sealing. Permanent magnet transmission, that is, permanent magnet coupling, is the safest solution for machinery that requires sealing, as well as for harmful, toxic, polluting, dangerous, pure, and valuable products and production processes. It has a wide range of applications. Most of the liquids in petrochemical, pharmaceutical, film, electroplating, nuclear power and other industries are corrosive, flammable, explosive, toxic, and valuable. Leakage will cause waste of working liquids and environmental pollution. ； Vacuum and semiconductor industries must prevent the intrusion of external gases: Food and medicine must ensure the purity and hygiene of the media. Permanent magnet transmission technology has found its way into these areas. British Howard Machinery Development Co., Ltd. (HMD) has been committed to the manufacture of sealless pumps since 1946, and has been operating in 37 countries around the world. * * Nearly 70,000 units have been sold, with annual sales reaching 28 million pounds. A pharmaceutical factory in the United States has hundreds of centrifugal pumps equipped with mechanical seals to handle various acids. Due to design problems, these pumps often run dry and destroy themselves after only 2 to 3 months of use. They replaced them with K1516 series magnetic transmission pumps produced by Ansimag Company. They were put into operation in 1993 (operating 4.8 hours a day, 365 days a year) and were still in operation in 1998. In a container plate factory in the Midwestern United States, synthetic caustic soda is a huge problem for the sealing of rotary vane pumps. Engineers here call these pumps "a maintenance nightmare." Ansimag's ETFE-lined sealless magnetic pumps were installed and have been running for 11 months without any downtime. A large chemical plant in the United States is facing severe difficulties in transporting methanol. Because methanol is flammable and close to boiling at 60°C, the flow rate is only 7m3/h, and the pressure difference is as high as 250m. The solution to the problem relies on the Dickow magnetic drive multi-stage end-suction pump, which has a flow rate of 15m3/h and a pressure difference of 400m, ensuring zero leakage of methanol, ensuring the safety of operators and factories, and solving the problem of transporting methanol containing bubbles. 2.2 The technical performance of magnetic pumps is developing towards micro and large-scale. In order to meet the needs of domestic and foreign markets, complete sets of equipment of petrochemical companies are developing towards large-scale. Our country must have a number of refineries with an annual output of tens of millions of tons and million-ton ethylene plants. Mechanical equipment must meet heavy load, long cycle, low energy consumption, and meet environmental protection requirements. When our country imitates foreign products, it is found that the material and process requirements for manufacturing magnetic pumps are very high. Even for small and medium-sized power pumps of 11 to 13 kW, the reliability and manufacturing cost are not acceptable to users. There is still a blank for high-power pumps that are resistant to strong corrosion, high pressure, and high temperature. The current development limit of magnetic pumps should be described by HMD's products: The flow rate is from 1m3/h to 681m3/h, the pressure difference is from 10m to 500m, the temperature range is from -100℃ to 450℃, the system pressure is from vacuum to 400bar, and the prime mover power reaches 350kW. Micropumps are specially developed for research and development in certain sectors, such as laser cooling, analytical instrument feeding, chemical replenishment, bioengineering, cooling cycles, and even printer nozzles. The gear pump and motor are integrated and closed, suitable for 24V and 36V DC power supply, and the speed is manually and automatically controlled. The minimum flow rate is 10ml/min, and the pressure difference is 7bar. The flow range of the MD series miniature magnetic transmission gear pump used by Japan Iwaki Company for electroplating and cooling cycles is 7.5~288L/min, and the transmission power is 1/25~1/3 horsepower. 2.3 Various types of pumps can be transformed into magnetic drive pumps. Centrifugal pumps are the leading product of magnetic drive pumps. Although magnetic drive rotary displacement pumps have a history of 25 years, they have only developed a broad foundation in design and manufacturing level and high torque capacity in the past seven or eight years. The focus is on the magnetic transmission gear pump and screw pump, with a maximum transmission capacity of 400Nm and a power of 150kW at a speed of 3500r/min. Located at the Utah Gas Power Plant on the border of the United States, the lubrication pump for the turbine compressor is a conventional external gear pump. The oil pump wears out due to excessive wear and tear on average every two months due to the high pressure difference, causing the compressor to shut down. After switching to a magnetic drive three-screw pump in 1992, it has been running continuously without any maintenance. British Tuthill has successfully applied its magnetic transmission gear pump to pump additives into the Scottish company's process water system. The pump replaced the screw pump and complied with health and safety regulations. 2.4 Magnetic drive compressor The inner bearing of the magnetic drive is located in the sealed space, which is lubricated and cooled by the sealed medium. In view of my country's material manufacturing level, magnetic transmission has not yet been applied in gas conveying machinery. The overpressure blower produced by Canadian Nova Magnetic Co., Ltd. has a leakage rate of 1cm3/h under 170bar helium pressure and a bearing life of more than 10,000 hours. Another series of pressurized fans have a free discharge flow of 750m3/h. At a flow rate of 400m3/h, the system pressure difference is 35MPa, achieving zero leakage. In addition, the special properties of magnetic transmission are also used in leak-free stirrers, valves and other equipment. The application in refrigerators has not yet received relevant information. The author is currently exploring the application of magnetic transmission in refrigeration compressors, because the leakage of refrigerants, especially Freon, will cause serious environmental problems. 3. New technologies, new processes, and new structures. Magnetic transmission technology is not simply the use of the same-sex repulsion and opposite-sex attraction effects of magnets. It is an integration of transmission technology, material technology, and manufacturing technology. This is the reason why world-class professional manufacturers have such a reputation in the world for their products that we cannot imitate them. Now these "veterans" are still making efficiency and quality improvements, reducing costs and extending the average time between inspections. 3.1 New materials and new processes The basic understanding of the selection of magnetic materials in various countries is unified. The working temperature of NdFeB material is lower than 150℃, and the working temperature of SmCo material is lower than 250℃. Barium ferrite can be used for micro pumps. Pump body materials are divided into two categories: metal and non-metal. Metal stainless steel does not mean that it is stainless for all liquids. It is mainly used for process liquids, precious liquids, and ultra-pure liquids that are compatible with it. Non-metals are specially developed for corrosive applications. It is divided into 2 situations. One is a pure plastic pump, thermoplastically molded in pure polypropylene or vinyl fluoride. For example, the flow rate of the British Vanton CGM pump is 136m3/h, the head is 84m (temperature 135℃), and the motor power is 32kW. The second is the lining pump, which is a currently popular method of lining corrosion-resistant pumps with plastic. Generally, the pump body can be made of malleable iron and seamlessly lined with FEP, PP, PFA, PVDF, and ETFE. A key advantage that sets Magnetix’s new MTA series sealless pumps apart from other lined pumps is its advanced PFA fluoropolymer lining. PFA is known for its unique ability to resist corrosion by a wider range of chemicals than ETFE, PVDF or other non-metallic materials. Using patented technology: Casting and lamination process, the connected PFA lining is thick and uniform, competing with rotational molding. It is more ideal for high purity and high temperature fluids. The minimum thickness of the PTFE lining of the ISO pump is 3mm, and the pump shell is pressed into the pump shell with tongue and groove. The pump shell is made of borosilicate glass. The isolation cover is a key component of the seal, and its rupture can cause catastrophic harm to fluid leakage. Single-layer metal enclosures have a wide range of applications. Although eddy currents will generate heat and energy losses, if high-strength and high-resistance materials are used, the losses can be limited to a minimum, such as: Hastelloy C-4(2.4610). The metal laminated isolation cover invented by Taiani has been patented in 5 countries and has been used in many designs. Its efficiency can reach 99% and the transmission power is 150 horsepower. The single-layer ceramic ZrO2 (zirconia) isolation cover is resistant to corrosion from caustic solutions and acids. It has high hardness and good sliding properties, as well as high mechanical strength and elasticity (E=2×105N/mm2). It has been used for working pressures of 250bar. However, the wall thickness of the ceramic cover is relatively large and cannot be plastically processed. For the IMO pump that received a US patent in early 1999, the new isolation cover is made of carbon fiber and epoxy resin, with a thickness of less than 2.8mm, and is connected to a stainless steel flange. Suitable for operating pressure 31bar, temperature 232℃, transmission torque 407Nm, power up to 149kW at 3600r/min. The double-layer isolation cover provides double insurance and space for inspection. Japan's IWAKI MDE series pump double-layer cover is made of glass fiber reinforced plastic. The AnSimag double-layer epoxy resin isolation cover magnetic transmission pump delivers alumina to the paper mill. It has been running for 2 years without replacing any parts. Isolation cover welding is the weak point of the structure and a sensitive source of corrosion. The advanced manufacturing method is plastic forming, such as deep drawing, spinning, and extension spinning. The shaft and sliding bearings are made of highly wear-resistant SiC. Dry running is generally a bad sign for sealless magnetic pumps. Careful fluid balance design, the rear sealing ring and the impeller hole work together to balance the axial thrust of the liquid and reduce the pressure on the impeller. The inlet adjustment valve prevents pre-rotation at low flow rates, reduces turbulence, and ensures low flow operation. The two sintered SiC bearings have optimized support points, and the spiral grooves in the sleeve help flush and lubricate the shaft diameter, providing a guarantee of 30 minutes of dry operation, allowing the operator time to adjust the system, restore normal operation, and avoid catastrophic damage. The pure SiC bearings of the MNKA series pumps of the German ITT Richter company can run dry for 1 hour at 2900r/min. 3.2 The new technology ensures economical and effective utilization of the magnet's volume with optimal physical dimensions. The correlation between magnetostatic disengagement torque and temperature is determined through finite element calculations and extensive testing. Axial and radial bearings are lubricated by pumped media. Lubricated channels provide the necessary flow. The new self-adjusting bearings can withstand large axial thrust and radial forces. Sliding bearings made of SiC or carbon graphite with superior corrosion resistance and wear resistance are shrunk in a metal shell to ensure the stability of mechanical operation. Even if the shaft shoulder is damaged, the reliability and maintainability of the bearing are still maintained. Another technique is fluid balancing, which minimizes the forces on the bearings. At present, the life of the inner bearing can reach 10,000h. High temperature problem: The KSB hot oil pump uses an annular cooler to surround the coupling chamber to keep the temperature near the magnet below the maximum allowable temperature of the material, although the average medium temperature is 350°C. HMD's eddy current coupling has a unique "torque circle" design that extends the temperature range to 450°C without cooling. Patented technology—fan automatic cooling: The magnetic coupling can be automatically cooled in various speed ranges without the need for an external cooling system. It is automatically completed using only an annular air chamber transmission. Complete reliability: A friction ring is installed on the magnetic coupling to protect the magnet ； To prevent dry running, flow sensors can be installed on user pipelines to determine interruption or low flow ； Foreign units are randomly equipped with digital power control monitors to determine overload conditions, leakage sensors, temperature sensors, and use PLC (programmable controller) to monitor the working conditions of the magnetic transmission in real time. Continuously monitor the running clearance of the outer bearing and monitor the wear of any ball shaft pump so that the shaft pump can be replaced in time before it is damaged. 3.3 New structure Almost all magnetic transmission pumps adopt a "rear pull-out" structure. The entire coupling components and bearing components are treated as a unit. It is not necessary to remove the pump casing from the pipeline and bottom seat when disassembling, which is convenient for maintenance and service. For example, Japan's Fujiyama Film Chemical Company used to use double mechanical seal centrifugal pumps. Due to corrosion and wear of chemicals, the shaft seals had to be replaced at least once. Replacing this seal is expensive, typically accounting for 25% of the total pump value, and takes up to 5 hours to replace. After switching to Global magnetic transmission pump, the operation was completely successful for 2 years. Compared with double mechanical seals, the maintenance cycle is doubled, and one assembly and disassembly is reduced to 15 minutes. In 1997, all delivery pumps were replaced with magnetic pumps, and the expected life of the pumps (without any service) was set at 5 years. ALLweiler rationally proposed an impeller-less shaft design. The impeller is installed in the middle of the SiC bearing, and the standard clearance is applying for a patent. The fan uses a separate electric motor and a plug-in sleeve bearing. Both the maintenance of the motor and the fan bearing can be completed within 30 minutes. Parts are widely interchangeable with standard pumps such as EN22858/ISO2858, ANSIB73.1, API610, DIN, and BS. Balancing is implemented according to API/ISO. 4 Advanced Manufacturing Technology and Management In order to adapt to global competition and cooperation, the world's pump industry is developing its own technological advantages and expanding its product range to adapt to the diverse and personalized needs of the world's large markets. While products meet functional requirements, there is no doubt that they should fully meet strict safety, reliability and ecological and environmental protection requirements. Advanced manufacturing technology is the theme of advanced products. HMD, a pioneer in magnetic transmission pumps, launched a long-term production approach and a complete research program three years ago, culminating in the redesign of its assembly equipment. It invested 1 million pounds to expand HMD's product capabilities, spent another 700,000 on a new high-speed machining system, and purchased 6 sets of machining centers. However, it is not only about using advanced machines to increase production, it is also important to establish flexible processing and reduce cycle times. In the past, the torque circle had to be transported 540m around the factory, and it took 8 to 9 weeks in the manufacturing chain. Today, manufacturing is a family-style organization. Many machines are connected to the company's CAD/CAM system. Engineers quickly make creative reforms to standard parts according to users and upload them directly to the machining center. The same torque circle running 30m only takes 2 days on the line. Due to rapid manufacturing, material pumps can be delivered very quickly, in some cases as little as 3 days. According to their words, "Competitive advantage will enable us to enter the next century and create more business opportunities." Advanced products come from advanced design and rigorous testing. 3D design and simulation, drawing-free processing, virtual manufacturing, and rapid prototyping are all in progress. Made by metallurgical testing of high-strength alloy materials, the pump body, impeller and isolation sleeve are subject to strong corrosion to ensure long life.: The non-wearing SiC shaft pump lubrication cooling system has been extensively tested in the chemical process industry and includes high system pressures of 345 bar, self-priming and shrink sleeve designs. Every part, component and system is meticulously inspected and rated. HMD believes that the principle of manufacturing and demand is: Advanced strategic raw materials ； Develop key supply relationships ； Reduce manufacturing cycle time by organizing manufacturing cycles ； Reduce queues and speed up processes. The author checked more than 20 well-known magnetic transmission companies on the Internet and found that they have subsidiaries and sales networks all over the world. Quality design and manufacturing are dictated by highly skilled pump issuers around the world to respond strategically and quickly to the market. Services include answering application problems encountered by users, pump selection, specially designed special pumps, and providing technical consultation to users 24 hours a day. Manufacturing technology in the 21st century will not only continue to manufacture machines and equipment that operate under normal conditions, but will also create machinery and equipment that operate in extreme environments. Products manufactured in the 21st century should be environmentally friendly and green products that are friendly to people. Magnetic transmission technology adapts to this development trend. Let us learn from advanced foreign experience to promote the development of this technology!