The upper temperature limit inside engine compartments is steadily rising, and the coolant system plumbing in new energy vehicles is becoming increasingly complex. These changes impose new demands on the temperature resistance and media compatibility of sealing materials. Liquid silicone rubber (LSR) seals, with their wide temperature range and stable chemical performance, are becoming an important option in powertrain sealing design.

LSR typically offers a service temperature range from -60°C to 250°C, enabling it to adapt to the full temperature spectrum – from extreme‑cold startup to high‑load operation. More importantly, LSR cured with a platinum vulcanization system can achieve a relatively low compression set. This means the seal maintains good rebound capability under long‑term compression, thereby preserving a stable sealing interface pressure.

In the structural design of seals, mold precision has a significant impact on final performance. Whether for O‑rings, custom‑shaped gaskets, or overmolded seals, the rationality of the mold runner system directly determines material flow balance during vulcanization. The location of the parting line is particularly critical. If the parting line falls on the sealing contact surface, it may create small flashes or irregularities, which can become the starting point of a leakage path. Therefore, precision molds combined with a well‑designed injection process are prerequisites for producing high‑quality seals.

Media resistance is another core consideration in automotive sealing applications. Different LSR formulations exhibit varying swell behavior in media such as engine oil, coolant, and battery electrolyte. Conventional LSR shows good compatibility with ethylene‑glycol‑based coolants and mild acidic/alkaline environments, but it may swell significantly in fuels and aromatic hydrocarbons. In such cases, fluorosilicone rubber (F‑LSR), which incorporates fluorine‑containing groups into its molecular chain, demonstrates superior oil resistance and is suitable for fuel systems and certain chemical media applications.

From design to production, the long‑term service performance of LSR seals depends on the systematic coordination of material selection, structural optimization, and process control. For automotive manufacturers and component suppliers, establishing a seal performance evaluation system based on actual operating conditions is essential to ensuring powertrain reliability.

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