Abstract
The paper deals with the effects of an MQL (Minimum Quantity of Liburication) process on drilling of 0.5% carbon steel. In drilling, discharge of chips from a hole drilled, tool wear, accuracy and surface roughness of the hole are the biggest problems, especially in deep drilling. MQL process gives fairly good results about these problems if suitable cutting conditions are selected. However the mechanisms have not been clarified yet. In this study, drilling tests with different lubrications, i.e. dry, MQL and wet, were carried out on the steel using solid carbide twist drills having two through holes. Tool life, cutting forces, profile and surface roughness of inside wall of drilled hole, enlargement and cylindricity of drilled holes were examined. Results obtained were as follows. (a) The longest tool life and the best quality of the drilled hole were obtained in MQL process. (b) Diameters of drilled holes in MQL process were larger than those in other process, while cylindricity of the hole in MQL process is better than that in other process. (c) The maximum torque in MQL process is smaller than that in other process.
