Sand and Solid Particles

Sand, or other abrasive grit, when introduced between sliding or rolling surfaces, creates an entirely different seizure phenomenon than friction from microscopic asperity collisions of relatively smooth surface finishes. It is well known that when sand gets into conventionally lubricated bearings, there is an almost immediate grinding away or seizing of the mating surfaces. It is now known, from many tests in which sand is added to POLYTRON treated oil, that conventional seizure does not occur. Furthermore, an ammeter monitoring frictional drag shows a momentary rise in consumed energy, possibly while the sand is being crushed; followed by a decrease in current draw, back to about the same level as before the sand was added. Particle size does not seem to be a major factor. Fine, powdery sand and grittier sand seem to react essentially the same.