SLIP STICK 17-5

A lack of lubrication between the seal faces can cause a destructive form of vibration called "slipstick". Without proper lubrication the lapped seal faces try to stick together, but "slip" when the seal drive mechanism engages the drive lugs and inertia accelerates the faces off of these lugs. The faces then slow down as a result of the poor lubrication.

This alternating "slipping" and "sticking" causes severe vibration, with a resultant "chipping" at the out side diameter of the carbon face, along with drive lug and slot wear.

Mechanical seals that use an o-ring as the secondary seal utilize the o-ring as a vibration damper. Metal bellows seals have a severe problem unless a damper is designed into the product.

 

 

The bellows seal damping device is shown in this illustration.

In this example the rotating face is allowed to touch the shaft. In other designs, the face holder I.D. is decreased and performs the same function

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