EVOLUTION AND RECENT TRENDS IN FRICTION DRILLING TECHNIQUE AND THE APPLICATION OF THERMOGRAPHY

Friction drilling is a new trend of hole making process in which the frictional force between the tool and work material is used for hole making, by thrusting of the tool into the work material without chips formation as like conventional drilling. During friction drilling ductility of the material increases with heat, which causes the material to extrude on the front and backsides of the hole, which forms the boss and bush respectively on the work piece, so it provides the required projection for threading. The damage to the surface occurring during the hole making, takes place at high temperature, which could be monitored using thermography. By using this technique damages occur during manufacturing can be monitored and minimized. Due to high temperature during drilling various phenomena like thermal phase transition, plastic flow of material and extrusion may occur, which directly influences mechanical properties and may cause plastic material from the hole surface. Friction drilling is used for hole making process of aerospace, automotive, commercial and industrial products.