Difference Between Metal Cased and Non Metal Cased Oil Seals?

Number of hits：162026-07-24 10:44:56　

The difference between a metal cased oil seal and a non metal cased oil seal can be summed up simply: one keeps its shape through a metal insert, and the other relies on the flexibility of rubber alone. This structural contrast leads to very different behaviors once the seal is installed and the machine begins to operate.

A metal cased oil seal stays stable when the shaft heats up, cools down, or experiences slight vibration. The metal insert helps the seal maintain its geometry, so the lip angle doesn’t shift easily. This stability matters in motors, gearboxes, and other systems where rotation speed or load changes frequently. When the seal’s shape stays consistent, the oil film at the lip can form more predictably, which supports long term sealing.

A non metal cased oil seal behaves differently. Without the metal insert, the seal is softer and more adaptable to tight spaces or housings with limited tolerance. This flexibility makes installation easier and helps the seal conform to the cavity. However, in high speed or high pressure environments, the rubber body may respond to load changes by slightly altering its shape, so it’s usually chosen for lighter or more stable applications.

In practice, metal cased seals appear in equipment that demands structural stability, while non metal cased seals are used where space, softness, or ease of installation matters more. The choice isn’t about which one is better—it’s about which one fits the machine’s operating rhythm.