Abstract
In this paper, the influence of concentration of sulfurous and phosphorous EP additives added on flank wear, crater wear of TiN- and (Al, Ti) N-coated tools, and finished surface roughness were investigated with minimal quantity lubrication (MQL) system in hobbing. Experiments were conducted by simulating hobbing by fly tool cutting on a milling machine. The results helped clarify the following points; (1) In the cases of polysulfide and sulfurized fatty oil, the flank wear decreased in the concentration of additive of 1.0 % (by weight), which showed a optimum concentration. In the case of tricresyl phosphate (TCP), the flank wear decreased with an increase in the concentration. Sulfurized fatty oil showed better wear reduction effect than any other additives. (2) When increasing in the concentration of the additives used in the tests, the crater wear becomes large, which was suggested to be caused by corrosion of additives. (3) Finished surface roughness obtained with EP additives tested is smaller than that obtained with no additive oil. (4) From the viewpoints of flank wear, crater wear and finished surface roughness, sulfurized fatty oil, of which the concentration is 1.0 %, is suitable for MQL system using (Al, Ti) N-coated tool in hobbing.
