Joule metal deposition—process features and stability of arcless wire melting

Abstract This paper provides a first insight into process conditions, parameters, and stability to continuously melt and fuse a metallic wire to a substrate by Joule heating. A force-controlled wire feed is a prerequisite to realizing a stable process as presented in this paper. The wire stickout should be as small as possible to reach the melting point in the contact zone and achieve stable, continuous melting. Constant and pulsed current can be used; however, pulsed current increases the process stability and eases ignition. For nickel-based materials, stainless steel and unalloyed steel currents required for bonding 1.2-mm wires are in the range of 750 to 1300 A, mostly dependent on the resistivity. An analytical approach to estimate the minimum required process current is deduced and verified with the experimental data. The analytical approach accounts for specific resistance and melting temperature of the molten material. A good agreement between experimental and analytical results was obtained for the materials tested in this work.