By Chris Wilson
A good bearing seal plays a key role in many bearings. Bearing seals actively do double duty, preventing contaminants from reaching the inside of your parts while keeping lubricants from leaking out. Both roles can help extend the life of your bearings, but it’s crucial to find the right seals for your parts. Let’s break down the different types of seals available for your bearing products.
A contact seal, also known as a lip seal, is a rubber part (typically Buna-N and nitrile) bonded to a steel insert. This seal is designed to apply continuous pressure on a bearing’s inner ring, which creates the contact found in the seal’s name.
By providing direct contact with the inner ring, contact seals make it extremely difficult for contaminants like dust, dirt, and moisture to reach the inner parts of your bearing. Contact seals also do an excellent job of sealing lubricants inside your bearing.
The trade-off for premium sealing performance is that contact with the inner bearing produces both friction and heat. Added friction and heat can damage both the bearing and the seal and lead to premature part failure. Addition friction can also reduce the maximum speed of the bearing, so you’ll need to weigh your need for top-end sealing performance with the potential for wear and tear and loss of top speed.
Like contact seals, non-contact seals typically Buna-N and nitrile rubber parts bonded to a steel insert. The main difference between the two is that non-contact seals are fixed to the outer ring and do not apply pressure to the inner ring of your bearing.
While non-contact bearings do not touch the inner ring, they do feature a thin lip that rests adjacent to it. This design provides protection against contaminants and leakage, but not to the same degree as a contact seal. However, the lack of contact with the inner bearing produces less friction, which can prevent overheating and other potential issues.
A labyrinth seal is a type of bearing isolator that combines elements of contact and non-contact seals in a single component. The idea of a labyrinth seal is to prevent leakage and contamination by creating a difficult path for both substances to follow. Labyrinth seals are composed of multiple pieces – one that remains stationary and another the rotates with the system. The two pieces interlock and create a thin, grooved path that is long and difficult for substances to escape or penetrate the bearing.
The complexity of a labyrinth seal allows it to provide excellent sealing capabilities. In addition, it can fend off contaminants and prevent leakage without contact the inner ring. As such, labyrinth seals offer the sealing capabilities of a contact seal while limiting added friction like a non-contact seal.
While labyrinth seals offer the best of both contact and non-contact seals, there are some potential downsides. The first is that the complexity of the design may require more physical space than other seals, which can be difficult to manage depending on your application. The second is that this same complexity can cause labyrinth seals to be more expensive than other sealing options. As such you’ll need to weigh the added benefits of these parts to determine if they make long-term sense for your situation.
IDENTIFY THE RIGHT SEALS FOR YOUR BEARINGS
There are a variety of factors that can impact your bearing seal selection, such as max temperatures, necessary lubricants, physical space, and more. Each element can not only affect which type of bearing is right for your application, it can also affect material needs and other details as well.
While seal selection plays a key role in the success of your bearings, you don’t have to make that decision alone. At Ritbearing, our experts can work with you to determine which bearings and bearing seals offer the best, most cost-effective solution for your application, environment, and end product.