If it's concerned that the rotary shaft seals have vital importance for the machines that the seals will be used with, the installation of the seals becomes more important. Improper installation and inadequate machining of the shaft or the bore would shorten the life of the seal and cause leakage and this result in the breakdown of the machines which cost much more than seals.

Things should be controlled before installation:

Rotary shaft seals should be removed from the packaging with hand only. And the use of sharp tools should not be attempted. Deformation can cause leakage.

The shaft that the seal will work with should have a surface hardness of 44 - 55 HRC. The shaft surface should be ground to a roughness of 1 - 4 mm. for rotary applications and to less than Rt = 1 mm. for reciprocating applications. The surface contact with the seal should be clean and free from rust.

If the seal is to be inserted over the shaft by the top face first, the shaft end should be chamfered and (Figure 4)the corners should be free from burrs.

If the seal is to be inserted over the shaft by the bottom face first, the shaft end should be radiused (Figure 4)

Figure 4: Tolerances and quality of shaft surface for seal installation

The surface roughness of the bore should be Rt 8 - 16 mm. the bore corners should be chamfered and burrs should be removed (Figure 5).

Figure 5: Recommended chamfer dimensions on bore

If the ends of the shaft can not be machined as required, or if splines or keyways exist on the shaft end, a special cap will have to be used (Figure 6 - 7).

Figure 6 : Mounting cap for shaft ends	Figure 7 : Installation device for shaft with splines or keyways

• The sealing lips and the outside surface should be lubricated slightly with the fluid to be sealed. If the dust lip is to contact grease should be applied between two lips.
• The top face (or the garter spring) of the seal should be facing the medium to be sealed
• Rotary shaft seals should be press - fitted by applying a uniform load on the bottom face. The load should be removed when the seal touches the bore base. In order to achieve this, the mounting devices should be used. The outside diameter of the device should be 0.5 mm. smaller than the bore diameter. The device should be designed so as to prevent distortion of the seal during installation.Hammers should never be used during installation.
• Once removed from its bore, a seal must never be used again. Before fitting the new seal, it must be ensured that the contact surface of the shaft is in proper condition . This can be done by the following steps:
  • Remachining the shaft.
  • Inseting a sleeve over the shaft.
  • Moving the seal along the bore.