By Christine Berlly
Bearings can come under attack from exposure to water and moisture, marine climates, and from a variety of chemicals (both gas and liquid). In today’s blog, we’ll look choosing seals and coatings in corrosive environments.
Certain types of bearings are available with integral seals. The seals protect the critical interior surfaces of the bearing from contaminant ingression. They also prevent lubricant leakage. When using bearings that do not have integral seals, consider external seal options.
Seals are typically a nitrile or Buna-N rubber compound. Teflon seals, which are highly resistant to most chemicals, are available on many types of bearings. Viton seals offer chemical resistance and are more robust than Teflon options.
Seal construction and shape can improve the effectiveness of the design. Labyrinth-type seals, where the seal lip sits in a groove machined in the inner ring, improve sealing capability without increasing torque. In addition, double-lip seals offer added protection compared to single-lip designs.
Anticorrosion coatings can be applied to bearings manufactured from either chrome or stainless steel to make the surfaces less chemically reactive than the base metal.
Surface engineering is highly specialized, so experts recommend consulting with a bearing manufacturer in selecting a coating or treatment. Anticorrosion coatings include TDC (thin dense chrome), cadmium plating, nickel plating, galvanized zinc, titanium nitride and carbide, and passivation (of stainless steel).