1: Material may not be the national standard bearing materials should be used GCR15 formal black GB bearing steel , through a full range of heat treatment process made ​​. Unlike household Shandong those assembled that slim tube drawing . 6204 what can be broken open with a hammer .
2 : bearing channel reduction techniques on handling stolen ( some manufacturers in Guan County, Shandong more common ) is the subject of the country with a large channel grinder , grind directly turner ferrule channel . Some small manufacturers often use trenching to replace grinder, can be thought of bearing life is very short . 3 : Bearing installation process does not work , some small manufacturers to use more rural cottage-style processing, no large-scale equipment, tend to use a very short time inside the bearing on the points left.
4: counterfeit components: carbon steel ball bearings or internal use thin cage .
5 : Bearing no cleaning or drying device does not function , bearing not after demagnetization , easily absorbed dust . Some small manufacturers tend to save costs, not directly on the bearings inside cleaning with white oil to cover bearing defects.
6: The bearing clearance is too small, some of the cottage bearing bearing clearance is difficult to achieve consistency in the bearing clearance is too small to affect the speed , too easy to swap sets. According roller working environment for general use C4 clearance . Old Model 4G204 new models 6204/C3 This is consistent with roller life.