An experimental study on the effects of lubrication in form tapping

This paper presents the results of a study of lubrication in form tapping and aims at a better understanding of its effect. It appears that lubrication is of paramount importance. Oil with efficient high pressure additives can reduce considerably the torque necessary to form the thread. Lubricants reduce the tool/work material friction during the forming process and, as a consequence, the resulting strain distribution and the strain hardening of the thread are affected. This investigation includes an analysis on the effects of additives in lubricants on the temperature during tapping, enabling correlation with the appearance of chemical elements of the oil which react with the thread material and contribute to lubrication.