Innovative developments in sealing technology

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Rubber and plastic seals are important basic components of mechanical products, and high manufacturing precision is required for them. With the rapid growth of automobile manufacturing and the number of vehicles in use in China, seal products need advanced technologies and equipment to support them both in terms of structure and materials. In recent years, some enterprises in China’s specialized sealing component manufacturing industry have adapted to market trends by promptly adjusting their industrial and product structures, thereby achieving rapid growth and development. While rapidly increasing output and production volume, significant investment has also been made in production and testing laboratory equipment. ◆Development trends of rubber and plastic sealing materials. Research is being conducted on the formulations and processing techniques of special rubber and plastic materials commonly used in rubber and plastic seals, such as nitrile, hydrogenated nitrile, fluororubber, acrylate rubber, and polytetrafluoroethylene; improving the performance and utilization efficiency of these materials remains a key focus of efforts. The application of nanomaterials will enhance the mechanical properties and special functions of rubber and plastic materials. Among the first four national standards for nanomaterials issued and implemented by the Standardization Committee on April 1 this year, one is the standard for \"nano-zinc oxide\" used in rubber. Specialty engineering elastomers replacing low-performance oil-resistant rubber ； Surface treatment of the rubber finish ； Some progress has been made in recent years in modifying rubber and plastic materials through nanotechnology and in the use of liquid rubber materials. In particular, the recent application of some new materials has greatly promoted rubber and plastic sealing technology. Thermoplastic elastomers (TPE), which are less widely used in seals in our country, possess the physical properties of vulcanized rubber along with the processability of thermoplastic resins. Since their molding process does not require vulcanization, they are considered to be the third generation of rubbers. Among the main types, TPO, TPV, and TPU are widely used around the world. The use of TPV in the automotive industry is growing at an annual rate of 15%; it is generally a fully cross-linked compound of EPDM and PP, offering high tensile strength as well as oil and heat resistance. It can withstand temperatures up to 150°C for extended periods, and can be used to replace EPDM in the production of automotive seals and other products ； Currently, TPO is mostly composed of ethylene propylene diene monomer and polyethylene components, with production methods including mechanical blending and dynamic vulcanization. In TPO produced by the dynamic vulcanization method. The rubber component accounts for 60–70%, offering high wear resistance, ozone resistance, tear strength, and low compressive deformation; its overall performance is superior to that of ethylene propylene diene monomer vulcanized rubber. The United States, Western Europe, and Asia are all continuing to build more TPO production facilities ； TPU combines the excellent processing properties of plastics with the physical properties of rubber; it boasts good wear resistance, low-temperature resistance, and radiation resistance. It has seen significant applications in industries such as automotive, aerospace, healthcare, household goods, and military supplies. TPU can be widely used in components such as car shock absorbers, bushings, bearing shells, sleeves, and airbags. ◆New materials introduced by domestic and foreign companies: 1. Perfluoroelastomer FFKM – it can withstand high temperatures (250°C to 320°C), is resistant to gases and severe chemical corrosion, has good elasticity, low permanent compression set, and other advantages, making it suitable for very demanding operating conditions. It is used in industries such as chemicals, food, printing, and semiconductors. Introduced by companies such as Parker and Evco. 2. Fluoroplastic-coated rubber products: Fluoroplastic materials such as FEP (fluoropropylene) and PFA (perfluorinated compounds) are used to coat rubber O-rings and gaskets (e.g., for sealing in plate heat exchangers), thereby enhancing the resistance of these rubber products to various media (solvents, strong acids, strong bases). Companies such as Shanghai Yigang, EVCO, and Fluorten offer such products. 3. The unique polyurethane material PU92AU21100 boasts excellent lubricity, and its ability to withstand extremely low temperatures reaches 20K (–253°C), making it suitable for use in conditions with such low temperatures. Exclusive to Simrit. 4. Composites and modifications of polytetrafluoroethylene (PTFE): To overcome the disadvantages of PTFE such as cold flow and poor thermal conductivity, and to reduce product wear, PTFE is used as a matrix and combined with materials such as carbon fiber, polyimide (PI), polyether ether ketone (PEEK), and polyphenylene sulfide (PPS) to develop oil-free lubrication seals (piston rings, guide rings, packing rings), which are widely used in medium- and high-pressure oil-free lubrication compressors. The seals developed by Guangyan Sealing are used in many well-known compressors in China. Applications of expanded polytetrafluoroethylene: This new material, created by stretching and expanding polytetrafluoroethylene, features a tough, porous, highly fibrous structure. It retains the unique chemical stability, extremely low friction coefficient, and wide operating temperature range of polytetrafluoroethylene itself; moreover, its microfiber-based internal structure endows its products with an unimaginably high level of toughness. ◆New product structures: In recent years, as attention has increased toward sealing technology, new sealing structures have emerged, meeting domestic market demands as well as those of the international market in terms of technical standards, quality, and cost-effectiveness. 1. New type of oil seal: This oil seal is equipped with a sensor for testing the leakage rate of the sealing mechanism (rotary seal), and can be used for online detection of leaks in equipment; it is exclusively offered by Simrit ； 2. Evd sealing system: When the seals of hydraulic cylinders wear out or deform, a specialized device is used to adjust the internal pressure of the seals (elastomers), thereby eliminating leaks. This system is used in equipment with very high reliability requirements (such as servo hydraulic cylinders and hydraulic cylinders used in water management systems). Launched by Hunger Company ； 3. The spindle equipped with the new SETCOAirShieldTM seal combines the advantages of a friction seal and a labyrinth seal. Compressed air is introduced tangentially into the circulation groove of the fixed front bearing housing, forming a closed labyrinth together with the main shaft. The air flows around the main shaft within the groove. Movement similar to eddies generates a uniform pressure, allowing the airflow to be distributed at a consistent rate. Combined with the flexible sealing lip, the escaping airflow blows away dirt from the main shaft, particularly from the bearings ； 4. Structural innovations in PTFE seals: Many new structures have been developed for PTFE seals, which are used for reciprocating sealing and rotary applications