From Oil Seal Manufacturers, we know that the primary causes of external lubricant leakage in pumping systems, hydraulic presses, gearboxes and tanks are incorrect selection, improper application, improper installation and improper maintenance of sealing systems. These problems can be overcome by better understanding the types of seal materials available, redefining the selection process, and consistently applying sound replacement and maintenance practices.
There are a number of variables that must be considered when selecting oil seals. When specifying oil seals, designers and maintenance engineers must evaluate nine factors:
The maximum shaft speed allowed is determined by the shaft finish, runout, concentricity of the housing bore and shaft, the type of fluid being sealed, and the type of oil seal material.
The temperature range of the mechanism where the oil seal is to be installed must not exceed the temperature range of the oil seal elastomer.
Most conventional Oil Seals are designed to withstand only very low pressures. If additional internal pressure exists or is expected, it is necessary to relieve the pressure.
If the shaft has a Rockwell hardness of 30 or higher, longer seal life can be expected. When exposed to abrasive contamination, the hardness should be increased to RC 60.
Surface treatment of the shaft
The most efficient seals are obtained by optimal shaft surface preparation. The sealing efficiency is influenced by the direction of the finishing tool marks and the spiral guide. The best sealing results are obtained with polished or ground shafts and concentric finishing marks. If you must use shafts with a spiral finish, they should face the fluid as the shaft rotates.
When the center of the bore and shaft do not coincide, the seal life is shortened because wear is concentrated on one side of the seal lip.
Shaft and Bore Tolerances
Best seal performance is achieved when shaft and bore tolerances are close. Other factors include shaft eccentricity, end face movement and vibration.
Runout must be kept to a minimum. Movement of the center of rotation is usually caused by bearing oscillation or shaft whipping. This problem is compounded when misalignment is added to the mix. Contrary to popular belief and common practice, installing a flexible coupling will not correct or compensate for misalignment.
Seals perform better and for longer when they are consistently lubricated with oil that has the correct viscosity and is compatible with the elastomeric material of the seal lip. Seal incompatibility considerations, especially with certain additives and some synthetic lubricants, should not be overlooked, but unfortunately, are often ignored.
The company also provides Agricultural Oil Seals, please feel free to contact us if you need.