The micro-cutting of steel with tungsten carbide tools can meet many of the demands of miniaturised components. A prerequisite for a stable machining process is a homogeneous, hard workpiece material with no internal stresses. The achievable surface roughness is between Rz = 0.5 μm and 1 μm. The most important process parameter is the cutting velocity. Depending on the hardness of the material, higher cutting velocities lead to better surface qualities. In order to improve the achievable surface quality a deeper understanding of the influence of the material properties on the minimum cutting depth is needed.