In addition to the standard axial and centrifugal design fans, many other airflow designs are used to meet customer applications. We now have backward curve motorised impellers, frameless fans, tangential cross flow blowers, flat blowers, chip coolers, CPU coolers, and combined heat pipes and fan assemblies.
Bearings have improved to meet the demands of less noise and higher performance. In addition to conventional ball and sleeve bearing fans, most manufacturers now offer different types of bearings such as the Hypro bearings from ADDA. A combination of ball and sleeve bearings in the same fan assembly is also used. These systems provide long life without having to use expensive ball bearings that are often the costliest component in a fan.
DC fans are now supplied with various degrees of ‘intelligence’ including fan failure and speed alarms, thermister based temperature control and pulse width modulated (PWM) control.
Frame and impeller designs have improved significantly over recent years and several types of impeller are now in common use such as sickle blade, paddle blade and static outlet blade fans.
