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Technical details for SELY bearings

 

Assembly and adjacent elements

libe recommends to get an easy coupling between the bearing and the construction to which it has to be screwed.
Exception to this recommendation are the cases where a very precise positioning is required.
A forced coupling might cause modification in the internal tensions.
If a very forced coupling is necessary, this condition should be clearly mentioned when ordering the parts.

The other elements which will be coupled with the bearings type SEL/Y have to guarantee and keep sufficient rigidity to prevent deformations due to coupling or screw assembly.

sely-vri-assembly

It is possible to use one more washer (not supplied) as support to the inner ring to increase the rigidity capacity of the bearing (assembly type VRI) – to be specified when ordering.

The bearings SEL/Y have to be assembled with screws having resistance class 10.9 through a torque wrench M (selected for each size). The screw tightening has to be carried out by crosswise sequence in three step. This procedure will allow a self-balance of the tightening forces in the screws.

The bearings series SEl/Y are supplied with two screws suitable for transport.
These screws can be loosened during centering to make operations easier but they have to ben tightened through wrench M (like the fixing screws) during final assembly.

ATTENTION: the bearings must not be dismounted! The screws used during transport must NEVER be completely loosened!

ATTENTION: incorrect screw assembly, in the inner ring especially, might cause wrong preload, thus compromising axial and radial run-out!

ATTENTION: if the assembly requires heating of the bearing or heating of the other components, please wait until the parts returned completely cold before starting working operations.

Rigidity

Rigidity is the capacity of a part to oppose the elastic deformation caused by a force applied on it. In short the formula is below, rigidity of a part k is deformed to quantity δ because of applied force P:

k = P/δ

The higher rigidity, the less will be the deformation borne when the part is subjected to the load. Bearing SEl/y is marked by high rigidity to tilting moments and to axial and radial forces.
This capacity make it the right choice in the working conditions where a high running precision is demanded when the load is applied.

Ka = axial rigidity

Kr = radial rigidity

Kt = tilting moments rigidity

 

Frictional torque

Frictional torque MRL hows the resistance to be won to keep the bearing rotation and it depends on more factors:

> running speed
> type and quantity of lubricant
> pre-load
> load applied

for this reason, the value MRL has to be considered purely an indication and referred to an even
rotation of 5 RPM at grease lubrication.

The starting torque or the torque at a different RPM could be slightly higher than reported.

The use of an additional washer for the inner ring (execution VRI) makes an increase of the frictional torque unavoidable.

Lubricant

Bearings type sEl/y are supplied with grease DIN 51825 KP2N-30 with mineral oil base and able to bear temperatures range -30/+140 °C.

The bearing can be relubricated through the holes in the inner and outer rings.

LI-BE guarantees that the bearings are supplied with the correct quantity of lubricant.
However we recommend to carry out a few rotations of the bearing while it is fixed without load to permit the correct distribution of the lubricant before putting it into use.

ATTENTION: too much lubricant can have consequences on the resistance to rotation MRL and on temperature production. In cases of overlubrication, please contact libe engineering department.

Tolerances – Axial and radial runout

ATTENTION: values related to completely fixed bearings.

Executions with restricted tolerances

 libe bearings series sEl/y can be requested with:

  • running tolerances (planarity and run-out) restricted 50%: …RI
  • reduced dimensional tolerances H1: …H1R
  • reduced dimensional tolerances H1 and H2: …H1H2R

ATTENZIONE: values related to completely fixed bearings.

Example of order: 1 bearing SEL/Y inner diameter 150 mm, reduced tolerances H1 and H2 and with restricted running tolerances will have following LI-BE designation:

SEL/Y150.H1H2R.RI

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