A powder metal bearing is a type of bearing made from powdered metal that is compacted and sintered to form a solid piece. These bearings are known for their ability to evenly distribute lubrication across their working surface, which enhances their performance and longevity. They are used in various applications, including control systems and fractional horsepower motors, and can be made from materials like bronze and iron graphite blends. Additionally, they can be impregnated with oil to further increase their lifespan and efficiency.

Bronze Powder Bearings

Bronze powder is the most common choice for bearings due to its excellent wear resistance and self-lubricating properties. These materials feature 12-30% interconnecting porosity to contain lubricating oil. With a 10% addition of tin, bronze provides corrosion resistance, can manage shock loading, and offers the necessary ductility for staking. Graphite is often added to the mix for improved lubricity, with the percentage ranging from 1% to 3.5% depending on the component's specific application requirements.

Iron or Ferrous Alloy Bearings

Iron or ferrous alloys are harder and stronger than bronze powder. Various alloys in this category are designed to meet specific component and application requirements. These bearings are often referred to as “structural bearings.”

Material Selection Considerations

Balancing the requirement for high porosity for lubrication with other operating conditions such as load, temperature, sound, and speed is crucial in material selection.