Figure 2.9. Metal to rubber bonded seal
Oil seals are available in an immense range of sizes, for shafts from a few millimetres to several metres. Once the shaft diameter, groove diameter (housing diameter) and groove width are known, selecting an appropriate oil seal is a simple task. An oil seal or its product description is usually associated with three dimensions, for example 6x15x4. These refer to the sizes of the hardware for which the oil seal is designed. In this example, this oil seal is suitable for: 6-mm shaft diameter x 15-mm groove diameter x 4-mm minimum groove width.
- 3. Low compression set High temperature rubber gaskets have low compression set, which ensures that they maintain their shape and seal effectively over time.
Improved low temperature resistance and same level of heat resistance as the standard type - A rubber valve cover gasket, a seemingly insignificant component in an engine's intricate machinery, plays a pivotal role in ensuring optimal performance and longevity. This article delves into the significance of these gaskets, their function, and the consequences of neglecting their maintenance.
No single physical property of rubbers is responsible for the successful performance of an oil seal or ‘O’ ring. The ultimate tensile strength, breaking elongation, modulus, shore hardness, creep and stress relaxation in tension and compression loads are all important physical properties that characterize a seal or ‘O’ ring. Compression strength and set together with stress relaxation or decay are important for effective sealing. The difference in these properties in a swollen seal is highly critical. An optimum swelling value in a fluid medium is a desirable feature. De-swelling decreases the seal pressure against the wall of the housing where the seal is fixed, leading to leakage. Over swelling minimizes the physical properties of the rubber. Seals made of polysulfide rubbers have extreme fuel resistance but undesirably high compression set. The effect of temperature on the seal is an important factor. Swelling under stress can increase at higher temperatures and a suitable compounding technique should be adopted to reduce this effect.
2、For products



The advantages are low friction and minimum power consumption, the possible use even in case of insufficient lubrication, operating range of -130º c to +200º c and much more: high chemical resistance and a low breakaway torque after standstill. Further, the PTFE, when heated, can” remember” its original form and return to it (phenomenon known as” plastic memory effect”).Therefore, this kind of seal do not need the old school metallic spring.
Similar to the housing surface stop technique, this method uses a stop at the machined housing face to set the seal depth. It is typically used in housings with flat outer surfaces. Verifying the placement through visual inspection or with a feeler gauge ensures placement accuracy.
