The importance of wall friction between particulate solids and elastomeric belt

A new experimental methodology is described for the combined measurements of both the static and the kinetic friction between a bulk solid and a conveyor belt. This area of investigation has all too often been neglected. The method of testing is based on a very well known principle of the operation of an inclined plane. The tester was designed while keeping in mind that tribological phenomena are influenced by various factors; these factors should be varied widely and independently, yet they should also be measured easily. In this preliminary testing using two coals and two rubber belts, several different operational conditions were used, such as load and moisture content. The experimental results confirm that both static and kinetic angles of friction between the belt surfaces and the coals tested are considerably higher than the presently recommended maximum inclination angle for belt conveyors. No two bulk materials are the same, and this is the reason why physical testing of a granular solid is so important to the proper design of conveying systems.