Under the action of the skeleton oil seal, the rigidity of the oil film just makes the oil film and the air contact end form a crescent surface, which prevents the leakage of the working medium and realizes the sealing of the rotating shaft. The sealing ability of the oil seal depends on the thickness of the oil film on the sealing surface. If the thickness is too large, the oil seal will leak; if the thickness is too small, dry friction may occur, causing the oil seal and shaft to wear; if there is no oil film between the sealing lip and the shaft, it is easy to cause heat and wear. . Therefore, when installing, it is necessary to apply some oil on the sealing ring, and at the same time ensure that the skeleton oil seal is perpendicular to the axis line. If it is not perpendicular, the sealing lip of the oil seal will drain the lubricating oil from the shaft, which will also lead to excessive sealing of the lip. wear. During operation, the lubricant in the casing seeps out a little, so that it is ideal to form an oil film on the sealing surface.
Double metal cased
In addition to these standardised types, the following special types are also available:
Regular inspection and replacement of oil seals are also necessary to prevent leakage and maintain the efficiency of the machinery. Over time, oil seals can wear out due to constant friction and exposure to harsh conditions, leading to leaks and potential damage to the equipment. By monitoring the condition of oil seals and replacing them as needed, operators can prevent costly downtime and repairs.
The durometer of an oil seal is typically dependent on the material it is made with. Common oil seal materials along with their durometers are as follows:
Table 2 b): Common types of oil seals (without spring)
When a seal is angularly misaligned – or cocked on the shaft – an irreversible process begins. Excessive pressure on one section of the seal, when not installed properly, can cause the spring to become dislodged or the seal to heat up and become brittle through excessive wear, both leading to a premature failure.
Oil seals come in various shapes to fit the machine or substance for sealing.
For this reason, when designing a machine, it is important to select the oil seal that is right for that machine.
Next time, we will explain the key points to consider when selecting your oil seal.
Polyacrylate is a great compromise between cost and quality. It has a high performing temperature and chemical range, but not to the extent of the range of Viton. The temperature ranges from 31°C to 148°C (-25°F to 300°F). Polyacrylate is primarily used in automotive transmissions and hoses but also found in shaft seals, gaskets and o-rings, due to offering a high resistance to hot oil and oxidation. While Polyacrylate is a great alternative to other high temperature resistant materials that are more expensive, it does have a poor water compatibility and cold flexibility. The best situation for Polyacrylate is an environment where heat and oil resistance but cost is the major issue. And while these 4 different materials cover a wide range of applications, there are even more materials out there designed for very specific niches in mind.