This paper presents some important relationships between chip forms produced with different chip-breaker grooves and fundamental characteristics of the cutting process. The interface control factor is proposed to be a main factor controlling the final shape of the chip. Experimental investigation showed that for all work materials being machined, rational chip-breaking performs at markedly reduced both plastic deformation in the chip formation zone and the cutting energy. Finally, the diagrams showing regions of acceptable chip form in relation to the process characteristics are presented.