2． Imperfections of Ball Bearing
A． Ball bearings are quite weak. It cannot bear any external
B． When the fan motor is operating, the steel balls inside will generate a higher rotational noise than that of a sleeve bearing.
C． High price makes it uneasy to compete with sleeve bearings.
D． Limitation on both supply sources and supply quantities make it unacceptable for mass production needs.
E． The use of tiny assemblies such as springs, result in inefficiencies for mass production