Use the Right Thickness of Lubricant

- To reduce friction by separating mating surfaces.
- To transfer heat (with oil lubrication).
- To protect from corrosion and, with grease lubrication, dirt ingress.
The successes of these three factors depend heavily on the film thickness on the raceway (simulated according to elastohydrodynamic effects) and at the rib/roller end contact.
Elastohydrodynamic lubrication – What is it?
The formation of the lubricant film between the mating bearing surfaces is called the elastohydrodynamic (EHD) mechanism of lubrication. The two major considerations in EHD lubrication are the elastic deformation of the contacting bodies under load and the hydrodynamic effects forcing the lubricant to separate the contacting surfaces while the pressure of the load is deforming them.
Film thickness on the raceway
The lubricant film thickness between two contact surfaces can be related to bearing performance. The thickness of the generated film depends on operating conditions such as velocity, load, lubricant viscosity and the relationship of pressure to viscosity.
Analytical relationships have been developed for calculating minimum and average film thickness for successful bearing performance:
To determine minimum film thickness:
hmin = KD (µoV)0.7a0.54W-0.13R0.43
hmin = KD (µoV)0.7a0.54W-0.13R0.43
where :
hmin = minimum lubricant film thickness
KD = constant containing moduli of elasticity
hmin = minimum lubricant film thickness
KD = constant containing moduli of elasticity
µo = lubricant viscosity at atmospheric pressure
V = relative surface velocity
a = lubricant pressure viscosity coefficient
W = load per unit length
R = equivalent radius
To determine average film thickness:
h = 0.039 (µVa)0.728 (P/ l)-0.091 (S 1/ R)0.364
h = 0.039 (µVa)0.728 (P/ l)-0.091 (S 1/ R)0.364
where :
h = lubricant film thickness (mm)
µ = viscosity of lubricant
V = surface velocity
a = lubricant pressure viscosity coefficient
P = load between inner race and rollers
l = effective length contact between rollers and inner race
S 1/ R = sum of inverses of contact radii
h = lubricant film thickness (mm)
µ = viscosity of lubricant
V = surface velocity
a = lubricant pressure viscosity coefficient
P = load between inner race and rollers
l = effective length contact between rollers and inner race
S 1/ R = sum of inverses of contact radii
Film thickness at rib/roller end contact
The contact between the large end of the roller and the inner race rib is called elastohydrodynamic contact or a hydrodynamic contact (as elastic deformations are negligible). As the rib/roller loads are much lower than the roller/race loads, the film at the rib/roller end contact is usually twice as thick as on the roller/race contact.
However, scoring and welding may still occur in severe conditions, including high speeds, viscosity, load or inadequate lubrication. In these conditions, use a lubricant with EP (extreme pressure) additives to prevent bearing damage.
Informacion muy util
ResponderEliminarEste comentario ha sido eliminado por el autor.
ResponderEliminarMuy buena información útil para una investigación compleja
ResponderEliminares importante saber el espesor del lubricante buena informacion
ResponderEliminares importante saber el espesor del lubricante buena informacion
ResponderEliminarAdemas de saver los tipos de lubricantes debemos tener en cuenta el espesor del lubricante ya que se utiliza dependiendo el trabajo que se va a realizar
ResponderEliminarBuena información, es de gran importancia saber el espesor correcto del lubricante.
ResponderEliminarDe gran importancia para no afectar el funcionamiento de las máquinas
ResponderEliminarEsta muy bien la informacion ya que no solo tenemos que saber el modo de lubricar, si no tambien, el espesor del lubricante
ResponderEliminarReconocer la importancia del espesor del lubricante, es muy importante para el buen funcionamiento de las máquinas.
ResponderEliminarBuena información, da a conocer el espesor del lubricante de las maquinas.
ResponderEliminarLa verdad la gráfica me parece muy buena solo que la información está en inglés y no soy muy bueno en eso
ResponderEliminarLa textura del lubricante que se piensa usar es muy favorable para la maquina alarga su vida y la mantiene en buenas condiciones
Una vez traducida la información es muy buena y completa
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