Unterschiedliche Korngröße und -orientierung des Werkstoffs bewirken eine unregelmäßige, wechselnde Spanbildung zwischen Fließspan und Scherspan. Mit zunehmendem Schneidkantenradius geht der Spantrennung eine starke plastische Verformung voraus. Erst nach Überschreiten einer Mindestspanungsdicke erfolgt die eigentliche Spanbildung. Geringe Zeitdehnung.

Process of chip formation in the orthogonal cutting of a polished and etched X 2 CrNi 18 9 austenitic stainless steel specimen. Due to variations in grain size and orientation within the structure of the material chip formation is irregular, varying between a genuine flow chip and a typical shearing chip. As the radius on the cutting edge grows which is a rather common occurrence in practice as the result of increasing wear on the cutting tool, the actucal severance of the chip is preceded by a marked plastic deformation of the material being cut. Not until a minimum chip thickness has been exceeded will the chip formation proper take place. Furthermore, as the radius on the cutting edge grows an increased tendency of material building up on the cutting edge can be observed.