Wear mode theory
While the usage of laboratory tests for determining abrasiveness of rocks is of limited value, they might be helpful in understanding the wear mechanisms operating during rock cutting. Apparently when crushed rock material is present between pin and rock, less wear occurs. This led to the development of a hypothesis of different wear mechanisms, or wear modes, occurring. H. J. R. Deketh developed the shaper test to study the transition of wear modes while testing rocks under different conditions. The displacement-controlled scraping test was developed to study the transition of wear modes while increasing the feed from zero to higher values. Rocks which are relatively strong with respect to the cutting machine will allow only shallow penetration. To examine the events that occur when a chisel enters the mortar rock, a simplified set of graphs is prepared. The graphs of specific energy and specific wear versus feed are of particular importance, because they indicate the economy of the cutting process.