A qualified imported ball bearings are made of high-quality bearing steel. The inner and outer rings and cages should be as bright as a mirror after wiping off the anti-rust oil, and should be smooth and delicate like glass when touched; the end surface of the outer ring should be coded, The place of origin and the date of leaving the factory are clearly marked; the rivets between the cages should be evenly riveted, and the rivet head should be straight and unbiased.
Support the inner ring with one hand, turn the outer ring with the other hand, the outer ring should be able to rotate quickly and freely, and then stop gradually ; make a stop mark on the outer ring, the stop position should be different every time it stops; hold the inner and outer rings with two hands respctively so that they can move relativly to each other in the radial and axial directions. There should be no gap-feeling. You may feel the gap in large bearing, but there should be sound free of metal impacting.
Through inspection above you can decide to purchase.A hardness test is also available (negotiated with the seller firstly to ensure the returns if the hardness does not meet the requirements): use a file or a hacksaw blade to file or scratch the outer and inner rings of the bearing if it makes a "gurgling" sound and has no crumbs, scratches, or only insignificant fine marks.
If the mark on the bearing is blurred, dull on the appearance , there is a gap when shaking, the outer ring rotates at the same position, there are chips or scratches when filing or the cage is rusted, any of which indicate that the bearing quality is unqualified.
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EFG BEARINGS (XIAMEN) CO., LTD.
Operation Center: 3F,No.169 Hongtangtou 1st Road,
Xike Town,Tong'an District,Xiamen Service Hotline: 400-812-9698 | 0086-592-5759320 E-mail: firstname.lastname@example.org