In the industrial manufacturing sector, seals serve as core sealing components, and their performance directly depends on the design and processing precision of injection molds. Seal injection molds cover various material-adapted types such as silicone and rubber, while precision seal injection molds meet the sealing requirements of high-end fields like automotive, hydraulic, and electronics with micron-level processing standards. Currently, as downstream industries raise higher demands for seals' temperature resistance, pressure resistance, and media resistance, seal injection molds are evolving toward multi-cavity, hot runner, and modular technical directions. The rationality of their design and processing precision are key manifestations of mold manufacturers' core competitiveness.
The key function of seal injection molds is to adapt to the molding needs of seals made from different materials. Silicone and rubber are the two most widely used raw materials currently, and the corresponding molds have distinct focuses in structural design and processing technology.
Silicone seal injection molds are mainly suitable for the molding of solid silicone and liquid silicone rubber (LSR). Silicone rubber itself exhibits excellent high and low temperature resistance (-60℃~200℃) and aging resistance, so the molds must adopt a hot runner structure to ensure uniform filling of the cavity with rubber material. Meanwhile, the surface roughness of the mold cavity should be controlled below Ra0.2μm to avoid surface defects on silicone products. Liquid silicone seal injection molds also need to be equipped with a precise metering and feeding system to achieve quantitative injection of rubber material, meeting the production standards for medical and food-grade seals.
Rubber seal injection molds target materials such as nitrile rubber (NBR), fluoroelastomer (FKM), and ethylene propylene diene monomer (EPDM). Such seals are often used in scenarios like hydraulic systems and automotive engines, so the molds need to enhance wear resistance and pressure resistance. The mold core is generally made of Cr12MoV alloy tool steel, which can reach a hardness of HRC58~62 after quenching, ensuring the service life of the mold under high-pressure injection conditions. Due to fluoroelastomer's poor fluidity and tendency to produce bubbles, fluoroelastomer seal injection molds need to specially optimize the venting structure.
Precision seal injection molds are specialized molds for high-precision seals such as O-rings and oil seals. The dimensional tolerance of the cavity must be controlled within ±0.01mm, and combined with the precise guiding structure of guide pillars and bushings, the mold clamping precision is guaranteed to meet the strict requirements for seals in automotive gearboxes, aerospace equipment, and other fields.
Mold design that fits actual production scenarios is crucial for improving the molding efficiency and quality of seals, and it should focus on three core modules: cavity layout, gating system, and temperature control system.
Cavity layout design must balance production efficiency and product precision. Multi-cavity molds are the current mainstream choice, with common cavity counts of 4, 8, and 16. Symmetrical arrangement is adopted to ensure consistent filling speed of molten material in each cavity. For special-shaped seal injection molds, a split-type cavity structure is used to facilitate mold maintenance and replacement, while reducing processing difficulty.
Gating system design should be adjusted according to material characteristics. Silicone seal injection molds preferably use a needle valve hot runner to reduce sprue residue and improve product qualification rate; rubber seal injection molds can adopt a cold runner structure, combined with the heat insulation design of the sprue bushing, to avoid premature vulcanization of rubber material in the runner. The gate position should be set on the non-working surface of the seal to prevent gate marks from affecting sealing performance.
Temperature control system design is directly related to the molding quality of seals. The mold needs to be equipped with a zoned temperature control device to control the mold temperature fluctuation within ±2℃. The mold temperature for silicone seal injection molds is usually set at 160℃~180℃, while that for rubber seal injection molds is adjusted to 150℃~170℃ according to the vulcanization characteristics of the rubber material. Precise temperature control can avoid defects such as uneven shrinkage and deformation of seals.
Currently, the seal injection mold industry is upgrading toward intelligence, greenization, and customization to meet the development needs of downstream industries.
The integration of intelligent technologies has become the mainstream. Molds are equipped with sensors to real-time monitor parameters such as cavity pressure and temperature, and realize real-time data transmission and analysis through industrial internet platforms. When parameters deviate, the system can automatically adjust injection process parameters to achieve adaptive mold production. Some high-end precision seal injection molds also integrate in-mold monitoring technology, which can online detect product dimensions and promptly reject unqualified products.
The concept of green design has gradually been implemented. Molds adopt a lightweight structural design, using high-strength aluminum alloy and other lightweight materials instead of traditional steel to reduce mold energy consumption and transportation costs; at the same time, optimize the cooling water channel design, adopting special-shaped water channels or 3D-printed conformal water channels to improve cooling efficiency, shorten the molding cycle by 10%~15%, and achieve energy conservation and consumption reduction.
Customization service capabilities have been continuously strengthened. In response to the demand for non-standard seals in emerging fields such as new energy vehicles and semiconductors, mold manufacturers provide integrated solutions from product design, mold development to mass production. Reverse engineering technology is used to quickly restore the structural parameters of customer samples, shortening the mold delivery cycle to 20~30 days to meet customers' rapid mass production needs.
In summary, the R&D and manufacturing of seal injection molds, silicone seal injection molds, rubber seal injection molds, and precision seal injection molds must be based on material adaptability, centered on precise design, and guided by technological upgrading to meet the performance requirements of seals in different industries. The refined control of each link, from mold material selection and cavity layout optimization to temperature control system debugging, is the key to ensuring the molding precision and production efficiency of seals. With the deep integration of intelligent manufacturing and green production concepts, the seal injection mold industry will further develop toward high precision, high efficiency, and customization in the future, providing solid mold support for the high-quality development of downstream fields such as automotive, hydraulic, electronics, and medical care, while helping mold manufacturers build differentiated core competitiveness in the fierce market competition.
