More about SKF bearings Bearings basics Friction Protection Lubrication Robustness Precision / ABEC Mounting / Removing Cleaning		Friction     Friction is "the" enemy when you talk about bearings for good skating. From 100 years experience we know that internal bearing friction mainly depends on following criteria: Lubrication Using an appropriate lubricant is a must to obtain low-friction.. But lubricant quality and quantity are equally important, since too much lubricant increases friction. SKF has decades of experience in lubricants testing and selection. Oil-lubricated bearings give better rolling than greased bearings, due to less friction between the components: balls, cage, seals and raceways. Free running time can even be doubled if one replaces the bearing grease by an appropriate oil. However oiled bearings needs to be lubricated very often. Greased bearings can also rotate very well, using an appropriate quality and quantity of grease. Trust SKF to get bearings with the right lubricant and quantity having lowest friction. Sealing design Standard rubber seals protect the bearings very well but at the cost of friction increase, resulting from the friction between seal and inner ring and also from the grease churning inside the bearing.Standard metallic shields avoid the sealing friction but do not avoid possible grease churning. They also have only a fair protection against dust and water. How did SKF solve this problem? - SKF has developed a non-contacting seal for inline skate. This seal ensures no friction from the seal with the inner ring and gives better protection compared to shields. - SKF has managed to reduce grease churning by applying a lower and controlled grease quantity. Cage shape and material: There are 2 main types of cages: moulded polyamide cages and steel embossed cages.SKF low-friction bearings use both cage types. They have the smallest contacting surfaces with the balls, and are equipped with lubricant retainers to avoid any direct contact of the cage with the balls.For tough use fibreglass reinforced polyamide cages are produced to ensure better strength and stress resistance. This does not create any additional friction. Manufacturing precision: The manufacturing precision of the bearing main dimensions is roughly described by ISO, ABEC or JIS standards (Read more on precision pages). Nevertheless, internal bearing friction mainly depends on the finishing quality of raceways and balls, which is not described by standards! SKF super-finishing process is the best way to ensure that lowest bearing friction can be expected. Bearing materials The materials used for rings and balls impact significantly the friction values. Also, some special high quality steels have better hardness and smaller roughness after super-finishing, which contributes to reduce friction. SKF has always used the best steels in order to reduce friction and to help the world move forward. It has been known for years that friction between ceramic balls and steel raceways is lower than friction between steel balls and steel railways, especially with reduced lubrication conditions.
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