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Dimensional stability, tight tolerances, resistance to extrusion damage, and wear resistance – these adjectives accurately describe the characteristics of Parker Hannifin’s polyurethane material seals. Over 20 years ago, Parker began producing Ultrathan and Resilon polyurethane materials, and since then, Parker’s polyurethane seals have continued to develop. It was first widely used in the field of hydraulic systems for walking machinery, followed by the pneumatic field, and eventually spread to various other industries. The operating temperature range of modern thermoplastic polyurethane (TPU) seals has expanded from -40°C to +120°C, and they can also handle highly corrosive media. At the same time, it also retains basic properties such as high resistance to extrusion and good wear resistance. Even without lubrication, the piston rod seal can move back and forth at a speed of 0.05 m/s under a pressure of 10 MPa. Long-term testing of piston seals for ISO standard cylinders has shown that the service life of polyurethane material seals is 5 to 6 times that of nitrile rubber material seals of the same shape and size. Breakthroughs were achieved in the use of polyurethane as a sealing material in the early 1980s. At that time, some manufacturers, including Parker Company, developed more hydrolysis-resistant polyurethane materials. These new polyurethane seals retained their elasticity even under high pressures and at temperatures up to +110°C, achieving better sealing performance as well as a longer service life compared to the previous polyurethanes (which could only withstand temperatures of +80°C). This achievement opened the door to hydraulic applications in walking machinery; prior to this, designers in this industry had great distrust of the original polyurethane material seals. In 1989, the Parker P5008 material was approved for use in Caterpillar’s global factories, an approval that marked a breakthrough in the application of Parker’s polyurethane material seals in earthmoving equipment. Thermoplastic polyurethane (TPU) seal systems have quickly and widely replaced the structures consisting of 5 to 7 fabric-reinforced rubber V-rings in excavator applications. That success over a decade ago prompted Parker Company to increase its investment in the development of new polyurethane materials. New \"customized\" thermoplastic polyurethane materials, a greater variety of seal shapes, and more economical production methods expand the potential range of applications. In the field of pneumatic sealing applications, Parker was the first in its industry to successfully offer polyurethane material seals in 1988. To meet the needs for oil-free lubrication in the pneumatic field, Parker has developed a range of sealing structures and special materials. Thanks to advantages such as a longer service life, greater wear resistance, and insensitivity to rough surfaces, polyurethane materials have also rapidly become standard materials in this field. Furthermore, the improvement in hydrolysis resistance has opened up new areas of application. Parker P5000 polyurethane can be used in equipment that employs oils compatible with the environment, such as canola oil ； The Parker P5500 seals have a high resistance to high-concentration acids or corrosive solutions, and can be used continuously in chemical plants at temperatures up to +80°C. Parker P5062 polyurethane material is particularly suitable for use as piston seals in hydraulic cylinders, as it possesses excellent thermal stability, with a high-temperature resistance of up to +110°C (with a peak of +125°C). P5011 polyurethane material, with a low friction coefficient and high wear resistance, is suitable as a seal for piston rods in low-pressure hydraulic equipment. P6000 is a newly developed type of polyurethane that boasts excellent wear resistance and resistance to extrusion; it is highly suitable for use as high-pressure or miniature seals, and can be applied in hydraulic excavators, hydraulic breakers, hydraulic shock absorbers, air springs, and other applications. Parker polyurethane material seals are increasingly proving their superior reliability, whether in the world’s largest excavators, the carbon dioxide valves of air guns, the automatic operation of car hood mechanisms, or the gas springs in the lower cabins of new zeppelins. Since the Parker Hannifin Sealing Group entered the field of fluid power in China in the 1990s, its polyurethane seals, with their excellent wear resistance, elasticity, hydrolysis resistance, and operational range across various temperatures, have provided reliable hydraulic and pneumatic sealing solutions for customers in industries such as construction equipment and machine tools. A typical application worth mentioning is the hydraulic sealing system in concrete machinery. The main cylinders used for concrete pumping operate under severe conditions: with pressures above 30 MPa, speeds of 1 m/s, oil temperatures reaching +70°C, and the piston rod ends being submerged in water. Since 1995, Parker China has been working in partnership with Sany Heavy Industry and Zoomlion, which are leaders in this industry, and Parker Seals has become the preferred brand in this sector. Experts from Parker’s factory in Germany designed polyurethane pistons specifically for Sany Heavy Industry’s concrete delivery cylinders; these pistons are used to push concrete and meet the machine’s requirements regarding resistance to hydrolysis and wear. This helps to extend the machine’s operating time, reduce the number of downtime incidents, and create more value for the machine owners. In the pneumatic industry, Parker seals are chosen by many well-known suppliers of pneumatic components such as Festo, Bosch Rexroth, and IMI Orgren. Domestic manufacturers such as Jinan Huaneng in China, Shanghai Xinyi, and Wuxi Hengli have also successfully applied Parker seals to their pneumatic components, thereby improving the sealing performance of these products. Parker’s MK polyurethane piston seals allow cylinder manufacturers to place magnets inside them; they also provide guidance and end cushioning functions. They are suitable for oil-free, short-stroke cylinders, and their standard material is P5010, which offers a longer service life than nitrile rubber. Leveraging the experience and knowledge gained from various engineering applications, along with further detailed analysis and experiments, Parker Hannifin Sealing Group is able to develop new material formulations tailored to specific customer applications.