An oil seal normally consists of three basic components: The Sealing Element (the nitrile rubber part), the Metal Case, and the Spring. It is a widely used sealing component. The function of a seal is to prevent the leakage of medium along the moving parts. This is mainly achieved by the sealing element.
NBR is the most commonly used seal material. It has good heat resistance properties, good resistance to oils, salt solutions, hydraulic oils, and petrol, diesel and other gasoline products. Operation temperatures are recommended from -40deg Cto 120deg C. It also functions well under dry environment.
The primary causes of external lubricant leaks on pumping systems, hydraulic presses, gearboxes and oil sumps are incorrect seal system selection, improper application, poor installation and improper maintenance.
These problems can be overcome by better understanding the types of seal materials available, redefining selection procedures, and consistently applying sound replacement and maintenance practices.
Many variables must be considered when selecting oil seals. When specifying oil seals, designers and maintenance engineers must evaluate nine factors.
Bluefkm TG Rubber Oil Seal
Maximum allowable shaft speed is a function of shaft finish, runout, bearing housing bore and shaft concentricity, type of fluid being sealed, and type of oil seal material.
The temperature range of the mechanism in which the seal is to be installed must not exceed the temperature range of the sealing elastomer.
Most conventional oil seals are designed to withstand only very low pressure applications (approximately 8 psi or less). If additional internal pressure is present or expected, pressure relief is required.
Longer seal life can be expected for shafts with a Rockwell (RC) hardness of 30 or higher. When exposed to abrasive contamination, the hardness should be increased to RC 60.
VMQ Red TC Rubber Oil Seal
The most efficient seal is obtained by optimal shaft surface finish. Sealing efficiency is influenced by the direction of the finishing tool marks and the spiral guide. The best sealing results are achieved by using polished or ground shafts with concentric (no spiral guide) finish marks. If you must use shafts with helical surfaces, they should lead to the fluid as the shaft rotates.
When the bore and shaft are not centered, seal life is shortened because wear is concentrated on one side of the seal lip.
Best seal performance is achieved when tight shaft and bore tolerances exist. Other factors include shaft eccentricity, end play and vibration.
Runout must be kept to a minimum. Movement of the center of rotation is usually caused by bearing wobble or shaft oscillation. When combined with misalignment, this problem becomes more complex. Contrary to popular belief and practice, installing a flexible coupling will not correct or compensate for misalignment.
Seals perform better and longer when they are continuously lubricated with an oil that has the correct viscosity for the application and is compatible with the elastomeric material of the seal lip.
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