Grease nipple

A grease nipple, also known as a grease fitting or zerk fitting, is a small but essential component used in lubrication systems to deliver grease under pressure into mechanical assemblies such as bearings, joints, linkages, and bushings. It provides a controlled entry point for a grease gun, allowing fresh lubricant to be injected directly into internal contact surfaces where friction and wear occur.

A typical grease nipple consists of a metal body made from steel, stainless steel, or brass, chosen for strength and corrosion resistance. Inside the body is a small spring-loaded ball valve. Under normal conditions, the ball seals the opening to prevent dirt, dust, water, and other contaminants from entering the lubrication system. When a grease gun nozzle is attached and pressure is applied, the ball is pushed inward, allowing grease to flow through the fitting and into the component being serviced. Once pressure is released, the spring forces the ball back into place, sealing the passage again.

Grease nipples come in different shapes and thread sizes depending on application requirements, including straight, angled (45° and 90°), and recessed designs for hard-to-reach areas. They are widely used in automotive systems, construction machinery, agricultural equipment, and industrial machines where regular lubrication is necessary for smooth operation and extended service life.

Manufacturing of grease nipples involves precision machining or cold forming of metal blanks, followed by threading, heat treatment (for steel types), and assembly of internal components such as the ball and spring. Final processes include surface finishing like zinc plating or galvanizing to improve corrosion resistance and ensure durability in harsh working environments.