Remelting and Coalescence of Molten Metal Droplets Deposited on a Plate

An experimental study was conducted to study coalescence of molten tin droplet deposited on an aluminum plate that was moving horizontally. A pneumatic droplet generator was used to produce molten tin droplets on demand. Coalescence of droplets placed on a horizontally moving surface depended on both substrate temperature and the degree of overlap between droplets. Continuous beads could be produced if the substrate temperature was kept above 175°C and droplets overlapped by a distance equal to half their diameter. If either substrate temperature or droplet overlap distance was too small surface tension driven instabilities forced the bead to break up. A simple mass conservation model was used to predict the width of beads formed by droplet coalescence.