Effects of Solid Lubricants During Compression Tests

During compression of a work-piece between dies or platens, such as in forging, coining and up-setting processes, any impact splashes out the liquid lubricant. Hence a solid lubricant is more effective. In the current study a PTFE, commonly known by the brand name Teflon, and a silicon spray were compared with a motor oil and dry friction (no lubricant). The experimental results were then compared with a finite element simulation model. Both the analyses show that the area under the true stress-strain curve is a minimum in the case of PTFE as a solid lubricant, and increases with silicon spray as the next, and then the motor oil, and finally the dry friction. This area gives the “Specific Forming Energy” for bulk plastic deformation, implying that the frictional losses are the least for PTFE as a lubricant, and increase with spray lubrication of silicon, followed by motor oil and dry friction. The experiments also show that barreling of the cylindrical surface of the work-piece is least for PTFE, and increases exactly in the same order: silicon spray, motor oil and dry friction.