Thermomechanical effects in laser microprocessing for dieless metal wire drawing

A new dieless metal fiber drawing process is developed in which a high-precision laser is used to heat the precursor wire to its superplastic temperature. The advantages of this technique over conventional cold drawing include larger diameter reduction ratio, no dies and lubricants, and the flexibility to draw fine wires of different diameters with the same apparatus. It is a promising process for the fabrication of fine wires that are difficult to draw with conventional processes or that require a high-quality surface without any contamination. The temperature profile generated by laser heating is critical in determining the plasticity and deformation behavior of the wire during the drawing process. The coupled thermomechanical problem is solved numerically for the temperature distribution and wire diameter reduction. Commercially pure nickel wires of initial diameter 125 mum are used as samples for laser drawing experiments, and the experimental results are compared with the model predictions. The wire drawing setup also provides a novel apparatus for evaluation of mechanical properties at high temperatures. (C) 2002 Laser Institute of America.