With the aid of a special experimental method it is possible to make the process of chip formation accessible for direct observation. Microcinematographical shots show penetration of the cutting blade into the skin of the polished and etched work piece structure. Hereby, due to the interaction of various types of behaviour from aspects of deformation and resistance of cut material on the one hand, and material stress on the other, caused by the cutting too, depending on cutting conditions, the formation of several chip shapes and built-up edges can be observed. The Ck 45 tempering steel, which was transformed by heat treatment into four different structural states with different mechanical properties, was cut at a speed of between 0.01 and 60 m/min. A wide spectrum of types of chips and built-up edge shapes can be seen. This is to be attributed to the interrelationship of influence on the work material, strain causes by the cutting wedge and cutting conditions. Resistance, stretch limit and stretching, combined with the cutting temperature caused by the cutting speed, go to create a complex mechanism of different influence.