In situ observation of lubricant film in a diamond die for wire drawing by micro-FTIR

Abstract

The performance of wire drawing is closely dependent on lubrication between die and metal wire. The behavior of lubricants between the die and the wire plays an important role in the lubricating performance for wire drawing. Therefore, the lubricant behavior should be made clearer by a direct observation of the drawing interface in die. The objective of this work is to understand the behavior of lubricants based on the chemical reactions for wire drawing. The drawing properties of these lubricants are discussed on the basis of the generation of metal soap. In situ observation of lubricant film during wire drawing was carried out using a micro-Fourier transform infrared spectroscopy (FTIR). The infrared (IR) spectra of oil film between die and metal wire can be obtained and oil film shape and concentration of additive can be estimated. It was found that oleic acid as an additive reacts with metal wire chemically and metal soap was formed. The concentration of metal soap was distributed to be high at the end of reduction zone under the dynamic conditions.