I. Project Background
As a critical component in various mechanical devices and everyday products, sealing rings play a vital role in preventing fluid leakage and ensuring system tightness. They are widely used in fields such as automotive engines, hydraulic systems, sanitary ware, and food and beverage packaging. Traditional sealing ring materials, such as nitrile rubber (NBR) and fluoroelastomer (FKM), have limitations in specific environments, including a narrow temperature resistance range, insufficient chemical corrosion resistance, and poor wear resistance—making it difficult for them to meet the demands of complex operating conditions and high-quality products. TPU material TPU-G65-MFQ, with its outstanding comprehensive performance, has opened up new avenues for enhancing the performance and fostering innovation in sealing ring products.
II. TPU - G65 - MFQ Material Properties
Outstanding chemical resistance: TPU-G65-MFQ exhibits excellent resistance to common acid and alkali solutions, organic solvents, lubricating oils, coolants, and other chemicals. In automotive engine cooling systems, where seals frequently come into contact with chemical media such as antifreeze, seals made from TPU-G65-MFQ do not exhibit swelling, hardening, or embrittlement, maintaining stable sealing performance over the long term. Testing has shown that after immersion in a 10% sulfuric acid solution at 80℃ for 1,000 hours, the volume change rate is less than 3%, and the hardness change remains within ±5 HA—far superior to conventional rubber seals.
Excellent wear resistance: This material boasts high hardness and outstanding wear resistance. Under conditions of high friction and heavy loads, the sealing ring’s surface is resistant to wear and scratches, effectively extending its service life. For example, in industrial hydraulic systems where the piston frequently moves relative to the cylinder bore under significant pressure, the TPU-G65-MFQ sealing ring, after undergoing 1 million reciprocating cycles, showed a wear amount of only 0.1 mm. Compared to nitrile rubber sealing rings, its wear resistance is more than three times greater, significantly reducing equipment maintenance and replacement costs.
Stability over a Wide Temperature Range: TPU-G65-MFQ maintains stable physical performance across a broad temperature range from -50℃ to 120℃. During the cold northern winters, seals used in outdoor equipment will not become brittle or lose elasticity due to low temperatures; instead, they will continue to fit tightly against sealing surfaces, effectively preventing leaks. Similarly, in high-temperature environments such as industrial furnaces and engines, these seals will not soften or deform under heat, ensuring reliable sealing performance. For example, in automotive turbocharging systems, where exhaust gas temperatures can exceed 100℃, TPU-G65-MFQ seals can operate reliably, effectively avoiding sealing failures caused by temperature fluctuations.
High elasticity and excellent sealing performance: TPU-G65-MFQ boasts outstanding elastic recovery capability. After being compressed or deformed, it can quickly return to its original shape, ensuring tight contact with the sealing surface and creating a well-sealed space that effectively prevents fluid leakage. Its microstructure enables it to adapt to varying degrees of surface roughness; even if the sealing surface has minor imperfections or irregularities, it can still achieve highly efficient sealing. For example, in sealing applications for bathroom faucets, the TPU-G65-MFQ sealing ring can closely fit the gap between the valve core and the valve body. Even after repeated opening and closing operations, it continues to maintain excellent sealing performance without any leaks.
Excellent processing performance: This material exhibits excellent melt flowability, making it suitable for a variety of processing techniques including injection molding, extrusion, and compression molding. During injection molding, it can rapidly fill the mold cavity, resulting in short cycle times and high production efficiency. Moreover, by precisely controlling processing parameters, it is possible to achieve precise control over the dimensional accuracy and shape of sealing rings, meeting the diverse design requirements of different application scenarios. For instance, for specially shaped sealing rings with complex geometries, TPU-G65-MFQ can be easily molded with high precision via injection molding, ensuring consistent and stable product quality.
III. Key Design Points for Sealing Rings
Shape and Size Optimization: Design appropriate seal ring shapes and sizes based on different application scenarios and sealing requirements. For static seals—such as pipe connections and equipment enclosure seals—a simple O-ring or rectangular seal ring can be used. For dynamic seals—such as rotating shaft seals and reciprocating piston seals—special structures like lip seals or skeleton-type seals must be selected to accommodate the friction and deformation caused by relative motion. At the same time, reasonably determine parameters such as the inner diameter, outer diameter, and cross-sectional dimensions of the seal ring to ensure a tight fit with the sealing area and provide sufficient sealing pressure. Generally, the cross-sectional diameter of an O-ring is chosen according to the sealing gap and pressure level, with common ranges between 1.8 and 5.3 mm. For lip seals, the thickness and angle of the lip need to be optimally designed based on the running speed and medium pressure to guarantee both excellent sealing performance and long service life.
Sealing Structure Design: The sealing structure of the sealing ring directly affects its sealing performance. Common sealing structures include single-seal, double-seal, and combined-seal designs. The single-seal structure is simple and suitable for low-pressure, low-demand sealing applications. In contrast, double-seal and combined-seal designs, through the synergistic action of multiple sealing elements, offer higher sealing reliability and are well-suited for harsh operating conditions such as high pressure, high vacuum, and strong corrosivity. For example, in the sealing of chemical equipment, a sealing structure combining a TPU-G65-MFQ lip seal with a metal skeleton can effectively resist the erosion of high-pressure, highly corrosive media, ensuring the safe operation of the equipment. Additionally, designing special textures or grooves on the edges and contact surfaces of the sealing ring can increase the sealing contact area, enhance sealing effectiveness, reduce friction resistance, and extend the service life of the sealing ring.
Design of Connection and Fixing Methods: To ensure that the sealing ring maintains a stable position during use without shifting or detaching, it is essential to design the connection and fixing methods appropriately. For small-sized sealing rings, direct installation into the sealing groove can be achieved through interference fits or snap-fit connections. However, for larger sealing rings—or those used in environments with high vibration and high impact—more robust fixing methods such as bolted fastening or welding are required. At the same time, it is crucial to select materials at the connection and fixing points that are highly compatible with TPU-G65-MFQ, thereby avoiding issues like electrochemical corrosion that could compromise the sealing ring’s performance and service life. For example, in automotive engine cylinder head sealing applications, a combination of metal gaskets and TPU-G65-MFQ sealing rings, secured by bolts, ensures that the sealing ring consistently maintains stable sealing performance even under the harsh operating conditions of high temperature, high pressure, and high vibration found in engines.
Color and Logo Design: Depending on the specific application scenario and brand requirements, the TPU-G65-MFQ sealing ring can be customized in a variety of colors. For instance, in the food and beverage industry, light colors such as white or transparent are often used to meet hygiene standards and facilitate easy identification. In industrial equipment applications, eye-catching colors like red or yellow may be chosen to serve as visual warnings. Additionally, brand logos, specifications, model numbers, applicable media, and operating temperature ranges can be printed or molded onto the surface of the sealing ring, making it easier for users to select and use the right product. This also helps with product quality traceability and management.
4. Production Process
Raw material preparation
TPU - G65 - MFQ Pre-treatment: Place the TPU - G65 - MFQ raw material in an oven at 80–90℃ and dry it for 4–6 hours to thoroughly remove moisture from the material. The presence of moisture during processing can lead to defects such as bubbles and silver streaks, seriously affecting the quality and performance of the sealing ring. The dried material should be used promptly to prevent reabsorption of moisture.
Mold Preparation: Based on the design requirements of the sealing ring, select appropriate mold materials and processing techniques to manufacture the mold. The mold surface must undergo high-precision polishing, with a surface roughness controlled below Ra0.4, to ensure a smooth sealing-ring surface and minimize the likelihood of fluid leakage. At the same time, conduct rigorous dimensional inspections and trial runs on the mold to guarantee its accuracy and molding performance, ensuring that the dimensional deviation of the produced sealing rings is kept within ±0.05 mm.
Injection Molding Process Parameters
Injection molding temperature: For TPU - G65 - MFQ, the injection molding temperature is typically maintained within the range of 180–200℃ to ensure thorough melting of the material, excellent flowability, and smooth filling of the mold cavity. In actual production, the injection molding temperature can be adjusted appropriately based on factors such as the type of injection molding machine, mold design, and product dimensions. For example, for thin-walled sealing rings, to ensure rapid material filling, the injection molding temperature can be slightly increased to 190–210℃; whereas for thick-walled sealing rings, to prevent overheating and decomposition of the material, the injection molding temperature can be slightly reduced to 170–190℃.
Injection Pressure and Speed: The injection pressure is determined based on the product’s shape, size, and mold structure, typically ranging from 70 to 100 MPa. The injection speed should not be too fast to avoid issues such as jetting or trapped air; it is usually controlled within the range of 20 to 50 mm/s. During the injection process, it is essential to ensure that the material fills the mold cavity uniformly and rapidly, thereby preventing defects such as insufficient filling or flash. For sealing rings with complex shapes, a multi-stage injection process can be employed, adjusting the injection pressure and speed at different stages to guarantee the quality of the final product.
Holding Pressure and Holding Time: The holding pressure is typically 50% to 70% of the injection pressure. The holding time is determined based on the product thickness and generally ranges from 3 to 10 seconds. The purpose of holding pressure is to replenish material into the mold cavity during the cooling and shrinkage process, thereby preventing defects such as sink marks and deformation. For thicker sealing rings, the holding time can be appropriately extended; for thinner sealing rings, the holding time can be slightly shortened. By optimizing the holding pressure process parameters, it is possible to effectively improve the dimensional accuracy and surface quality of the sealing rings.
Cooling Time: The cooling time is determined by the product thickness and the efficiency of the mold cooling system, typically ranging from 8 to 20 seconds. During the cooling process, it is essential to ensure that the product cools sufficiently and sets properly without deforming when demolded. By optimizing the mold cooling system—such as adopting circulating water cooling, increasing the number of cooling channels, and arranging them rationally—we can effectively shorten the cooling time and enhance production efficiency. At the same time, during the cooling process, it is important to maintain a uniform cooling rate to prevent uneven cooling, which could lead to stress concentration inside the product and compromise its performance.
Post-processing technology
Trimming and Finishing: After injection molding, the sealing rings must undergo edge trimming to remove excess flash and burrs, ensuring a clean and neat product appearance. At the same time, the product surface should be carefully inspected and finished to ensure it is free of defects and scratches. For sealing rings with high precision requirements, additional post-processing steps such as grinding and polishing are also necessary to further enhance the surface quality of the product.
Sealing Performance Testing: Each sealing ring undergoes rigorous sealing performance testing, simulating real-world usage scenarios. By applying specific pressure and media, the test detects whether any leakage occurs in the sealing ring. For products that fail to meet the required sealing performance standards, we analyze the underlying causes and either make adjustments or discard them. Common sealing performance testing methods include air pressure testing, hydrostatic pressure testing, and helium mass spectrometry leak detection. The appropriate testing method is selected based on the specific application scenario and sealing requirements.
Packaging and Warehousing: Seal rings that have passed inspection shall be packaged using appropriate packaging materials and methods based on their specifications and quantities. During the packaging process, care must be taken to protect the surface of the seal rings against scratches and contamination. Typically, plastic films and cardboard boxes are used as packaging materials. After sealing rings are individually or collectively packaged, they are placed into cartons for storage. Once packaging is complete, the products are stored in the warehouse awaiting shipment. At the same time, inventory management and product labeling should be carried out meticulously to facilitate traceability and easy retrieval of information.
V. Quality Control
Raw Material Quality Control: Establish a rigorous supplier screening system to select suppliers with strong reputations and stable quality. Each batch of TPU-G65-MFQ raw materials must undergo comprehensive quality testing upon arrival at the factory, covering indicators such as hardness, tensile strength, tear strength, chemical resistance, and temperature resistance. Only raw materials that pass the inspection are allowed to enter production, thereby ensuring product quality from the very beginning. At the same time, suppliers are regularly evaluated and audited to guarantee the stability and reliability of raw material quality.
Process Quality Monitoring: During the production process, multiple quality monitoring points are established to conduct real-time monitoring of injection molding process parameters, product appearance, dimensions, and other critical factors. Advanced sensor technology and automated control systems are employed to ensure the stability of process parameters. Online inspection equipment, such as laser measuring instruments and vision inspection systems, is used to perform rapid and accurate checks on product appearance and dimensions. Once any quality issues are detected, process parameters are promptly adjusted or production is halted for corrective actions. At the same time, production equipment undergoes regular maintenance and servicing to ensure its proper operation and prevent quality problems caused by equipment failures. For example, temperature and pressure parameters of the injection molding machine are inspected and recorded every two hours; and a random sample of products is checked for appearance and dimensions after every 100 units are produced.
Finished Product Quality Sampling Inspection: For finished seals, a sampling inspection is conducted according to a specified ratio. In addition to routine inspections covering appearance, dimensions, and sealing performance, the products are also tested for resistance to aging and fatigue. The aging resistance test employs an accelerated aging test conducted artificially, simulating harsh environmental conditions such as ultraviolet radiation, high temperatures, and high humidity, to assess how the product’s performance changes over prolonged use. The fatigue resistance test involves subjecting the seals to repeated compression and tensile cycles to evaluate their sealing performance and service life under long-term dynamic operating conditions. Any batch of products failing the sampling inspection will be entirely reworked or scrapped to ensure that all products leaving the factory meet quality standards. For example, each month, 50 units of each different seal specification are randomly selected for finished-product quality sampling. The sealing performance is tested using a pneumatic pressure test method: the seals are pressurized to 0.5 MPa and held for 5 minutes, after which any leakage is observed. The aging resistance test is performed using a xenon lamp aging chamber in accordance with the GB/T 16422.2 standard, with an aging duration of 1,000 hours.
VI. Cost Analysis
Material Costs: The TPU—G65—MFQ material has a relatively high price. However, given its outstanding performance and long service life, it can help reduce after-sales maintenance costs and the frequency of product replacements. By optimizing product design and appropriately controlling the size and thickness of the sealing rings, we can further reduce material usage and thereby lower material costs. For example, while maintaining the same sealing performance, reducing the thickness of the sealing ring from the original 3 mm to 2.5 mm can cut material consumption by approximately 17%. At the same time, establishing long-term, stable partnerships with suppliers and adopting strategies such as bulk purchasing and supply chain optimization can help secure more favorable procurement prices and reduce material acquisition costs.
Mold Costs: The design and manufacture of sealing-ring molds are relatively complex and thus come with higher costs. However, by collaborating with professional mold manufacturers, adopting advanced mold-design software and manufacturing processes, optimizing mold structures, and extending mold service life, it’s possible to spread out the mold costs. Meanwhile, as production volumes increase, the proportion of mold costs in total expenses will gradually decrease. For example, using hot-runner molds can reduce material waste, boost production efficiency, and lower mold operating costs. Selecting high-quality mold steels, such as SKD11, can enhance the wear resistance and service life of molds, thereby reducing the frequency of repairs and replacements. In addition, implementing meticulous mold management and performing regular maintenance and upkeep can extend the service life of molds, effectively lowering mold costs as well.
Production efficiency costs: TPU - G65 - MFQ boasts excellent processing performance and reasonably set injection molding process parameters, which can enhance production efficiency, shorten the production cycle, and reduce labor costs and equipment energy consumption costs. By optimizing the production process and reducing the defect rate, production costs can also be effectively lowered. For example, by fine-tuning the injection molding process parameters, the yield of good-quality products can be increased from 93% to 96%, thereby reducing the per-unit production cost by approximately 3%. Moreover, adopting automated production equipment—such as automatic injection molding machines, automatic trimming devices, and automatic inspection equipment—can further boost production efficiency and cut labor costs. Additionally, arranging the production schedule rationally, avoiding equipment idle time and unnecessary overtime work for personnel, can also help lower production efficiency costs.
VII. Market Prospects
With the rapid advancement of industrial automation and intelligence, as well as the continually rising demands for quality of life, higher requirements are being placed on the performance and quality of sealing ring products. The TPU-G65-MFQ material has garnered widespread market attention due to its remarkable advantages in sealing ring applications, including excellent chemical resistance, outstanding wear resistance, broad temperature stability, and superior elastic sealing performance. In industries such as automotive manufacturing, aerospace, electronics and electrical appliances, chemical processing, and food and beverage, TPU-G65-MFQ sealing rings hold great potential for widespread adoption. For instance, in critical components of new-energy vehicles—such as battery pack seals and motor seals—TPU-G65-MFQ sealing rings can meet stringent requirements for high reliability and long service life, thereby ensuring the safe operation of new-energy vehicles. In the food and beverage packaging industry, the hygienic, non-toxic, and chemically resistant properties of TPU-G65-MFQ sealing rings help guarantee the quality and safety of food and beverages. Meanwhile, as technology continues to advance and costs continue to decline, the application of TPU-G65-MFQ material in the sealing ring sector will keep expanding, offering exceptionally promising market prospects. It is projected that over the next five years, demand for TPU-G65-MFQ sealing rings will grow at a rate of 10% to 15% annually, making it a key growth driver in the sealing ring market.