Dieless laser drawing of fine metal wires

A novel dieless drawing technique is presented for processing contamination-free metal wires with controlled surface chemistry. Such wires are particularly useful to produce filters for high-pressure and high-temperature corrosive filtration applications, catalysts, micron size electrical conductors, and ornaments with gold fibers requiring good optical surface properties. Laser wire drawing is a non-contact process in which a laser beam is used to heat the wire to a critical temperature range corresponding to its plastic state. This process is generally good for small diameter wires. Due to high precision heating capability of lasers, the temperature of the wire can be maintained at a desired level to achieve maximum ductility. Ni-200 wires of initial diameters 500 and 125 μm, respectively, were used to develop a dieless laser wire drawing process. The maximum diameter reduction ratio, the effect of drawing environment on the surface quality and the diameter uniformity of the resultant wire were analyzed. An oxidation prevention device was fabricated to attain large cross-sectional area reduction ratio without surface oxidation. The diameter of the wire becomes more non-uniform as the diameter reduction ratio increases. This is a flexible technique because a single apparatus can be used to draw various wires of different elements and alloys.