Interaction between Additives in Metalworking Fluids under Difficult Cutting Conditions

Abstract

In order to investigate the interaction between additives in metalworking fluids under difficult cutting conditions, tapping tests were conducted under different metalworking conditions for metalworking fluids consisting of liquid paraffin added with tricresyl phosphate (TCP), polysulfide (PS), and oleic acid (OA). The tapping torque was measured for tapping M6 threads in S45C steel by using workpieces designed with relatively small prepared hole for creating difficult cutting conditions. For evaluating the effect of metalworking fluids, two quantities - mean tapping torque (Nmean) and maximum tapping torque (Nmax) - in the tapping torque signals were introduced. When one of the extreme-pressure (EP) agents, i.e., TCP or PS, is added into the liquid paraffin, both Nmean and Nmax decrease considerably. Moreover, when both the EP agents are added, the values of both Nmean and Nmax are smaller than those obtained for the same concentration of a single EP agent; this implies the synergy between TCP and PS. OA, when used with the two EP agents, does not always decrease the values of Nmean and Nmax; there exists an optimal concentration level for TCP, PS, and OA for minimizing the values of Nmean or Nmax.

Keywords

• difficult cutting
• tapping
• metalworking fluid
• extreme-pressure agent
• oiliness agent
• tricresyl phosphate
• polysulfide
• oleic acid