Belt Loading

To assure proper performance of a metal belt, a load analysis is necessary.  The purpose of the belt and pulley system is to transfer the motion profile of the system controller through the driving pulley to the belt.  The primary power transmission consideration is that power transmission be slip free.  The driven (idler) pulley provides an opposing force for the purposes of belt tensioning and steering.

A load is on the belt in the form of the belt being dragged over a cooling, heating, vacuum or support plennum, plus tooling nests attached to the belt or the weight of parts being processed.

Automation and conveying processes depend on the belt, under load, to operate within some defined motion profile parameter.  Usually, this is a fixed belt speed of some feet per minute.  For an automated assembly belt being precision position indexed, the motion profile is one of acceleration/deceleration/dwell.

We want the belt to move per the motion profile as generated by the system's controller.  This can only be accomplished when the drive is slip free.  Preload tension is introduced in the belt by driven pulley adjustment relative to a fixed driving pulley.

Metal belts depend on friction to transmit power from the drive pulley to the belt. The belt's angle of wrap on the drive pulley, the coefficient of friction between the pulley and belt, and belt tension are the variables that determine the power transmission capability.

Due to the low mass of thin metal belts, centrifugal force will not reduce surface pressures between the driving pulley and the belt.  For the purposes of load analysis, centrifugal forces are considered net neutral.