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Why Are Rod End and Spherical Bearings Teflon-lined?


A PTFE (Du Pont trademarked product) liner in a spherical bearing or rod end is a component that allows the unit to be "self-lubricating". Metal on metal bearings need to be lubricated. In certain applications this can be difficult to accomplish. Grease lubrication attracts dirt and may prematurely wear apposing metal surfaces. Excessive wear will produce increased fatigue and ultimately leads to an expensive failure.

A PTFE liner eliminates the need to lubricate spherical and rod end bearings. A PTFE liner usually consists of a base fabric containing PTFE that is applied to a metal surface with a bonding resin. The liner is adhered to the inner portion of the bearings outer race(Body). This allows the ball to ride on the surface of the liner. When the ball moves it literally rubs on the liner providing the bearings' lubrication. It is important to understand that an exceptionally good PTFE liner will have a minimum compressive strength of 40,000 psi. A liner of this type greatly reduces internal clearance between the ball and race allowing for a much tighter fit. Recent improvements to self-lubricating liner systems have allowed certain manufacturers the ability to offer products with life cycles four times greater then previously available.

When choosing a PTFE-lined spherical or rod end bearing it is important to select a manufacturer with considerable experience and knowledge. Bonding PTFE liners can be a bit tricky as the nature of the liner can make it difficult to bond to the race. An incorrect bond process may ultimately result in separation of the liner from the race. Liner separation will quickly lead to degradation of the liner and ball. Spherical and rod end failure can be catastrophic. PTFE lining standards vary between manufacturers and should be carefully considered when choosing a supplier. Next time you are in the market for a PTFE-lined spherical or rod end let National Precision Bearing help provide you with the appropriate manufacturer and liner for your application. Please contact our professionals for assistance.

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