In the production of silicone seals, controlling the vulcanization process parameters is crucial to avoiding insufficient sealant. Vulcanization is a key step in the molding of silicone seals, using high temperature and pressure to cause a chemical reaction in the silicone material, forming a stable elastomer. Improper control of vulcanization parameters can easily lead to defects such as insufficient sealant, bubbles, and deformation, affecting sealing performance and service life. Therefore, comprehensive control from multiple dimensions, including vulcanization temperature, vulcanization time, vulcanization pressure, mold design, and operating procedures, is necessary to ensure a stable and reliable vulcanization process.
Vulcanization temperature is a core parameter affecting the vulcanization speed and cross-linking density of silicone. If the temperature is too low, the vulcanization reaction is slow, and the silicone cannot fully cross-link, resulting in insufficient strength and easy deformation; if the temperature is too high, it may cause over-vulcanization, leading to the breakage of silicone molecular chains, a decrease in physical properties, and even problems such as scorching and bubbles. Therefore, the vulcanization temperature range must be precisely set according to the type of silicone, the thickness of the product, and process requirements. For example, the vulcanization temperature of ordinary silicone seals is usually controlled within a suitable range, while thick-walled or complex-structured products require a staged heating process, preheating at a low temperature followed by high-temperature vulcanization to avoid surface overheating and internal under-vulcanization.
The vulcanization time directly affects the degree of silicone vulcanization. Too short a time results in incomplete curing, easily leading to insufficient curing and mold sticking; too long a time reduces production efficiency and may cause performance degradation due to over-vulcanization. The vulcanization time setting must comprehensively consider the vulcanization temperature, product thickness, and silicone formulation. For example, thin-walled products can use a shorter vulcanization time to improve efficiency, while thick-walled products require a longer vulcanization time to ensure sufficient internal curing. Furthermore, temperature stability must be maintained during vulcanization to avoid errors in vulcanization time calculation due to temperature fluctuations.
Vulcanization pressure is a key factor in promoting silicone flow, filling the mold cavity, and forming a dense structure. Insufficient pressure prevents the silicone from fully filling the mold corners, resulting in insufficient curing; excessive pressure may cause overflow, mold deformation, or stress concentration within the silicone. Therefore, the vulcanization pressure must be set appropriately based on the shape, size, and silicone flowability of the product. For example, complex-structured seals require higher pressure to ensure sufficient silicone flow, while simple-shaped products can have lower pressure to reduce the risk of silicone overflow. Simultaneously, pressure stability must be maintained during vulcanization to avoid dimensional deviations caused by pressure fluctuations.
Mold design has a significant impact on the control of vulcanization process parameters. The mold's runner structure, venting groove design, and parting surface accuracy directly affect the silicone flowability and filling effect. For example, a reasonable runner design can reduce silicone flow resistance and avoid localized short-filling; venting grooves can expel air from the mold cavity and prevent bubble formation; and parting surface accuracy affects the flash and sealing performance of the product. Therefore, thorough simulation analysis and structural design optimization are necessary during the mold development stage to ensure that the silicone can fill the mold cavity uniformly and quickly during vulcanization.
Strict adherence to operating procedures is crucial to preventing silicone short-filling. Before production, the mold must be cleaned and preheated to ensure uniform mold cavity temperature. Raw materials must be accurately weighed according to the specified ratio to avoid incomplete vulcanization due to formula errors. During vulcanization, the equipment's operating status must be checked regularly to ensure stable temperature and pressure parameters. After vulcanization, the temperature must be lowered slowly to prevent cracking of the product due to thermal stress. Furthermore, operators must receive professional training, be familiar with the vulcanization process and key quality control points, and be able to promptly identify and handle abnormal situations.
Controlling the vulcanization process parameters for silicone seals requires coordinated optimization from multiple aspects, including temperature, time, pressure, mold design, and operating procedures. By accurately setting vulcanization parameters, optimizing the mold structure, and strictly adhering to operating procedures, insufficient resin can be effectively avoided, improving product quality and production efficiency.
