The tin alloy, which had a very low liquid fraction, would not be a suitable tooling material, but it does provide a striking example of the heat dissipation possible with the process. McHugh estimated that the process could be used to create about 70 percent of the tools used in industry. Key Differences RSP differs significantly from other commercial spray metal techniques, broadly known as thermal spray, according to McHugh. One of these, arc spraying, uses the feedstock metal in the form of two wires that are kept on a spool. The wires are fed into a spray gun and an arc is struck, producing enough energy to melt the wire tips.
Gas is blown over the tips to form droplets that are deposited on a pattern.
In arc spraying, the metal must be ductile enough to be wound into a wire, which may eliminate using materials such as tool steels, McHugh said. Arc spraying systems typically use materials such as zinc-based alloys, which are quite ductile, and are limited to outputs of approximately 15 pounds per hour. RSP, by contrast, can be applied to a broad range of tooling alloys and can handle high outputs. A bench-scale system now at the laboratory is capable of deposition rates of 500 pounds per hour. In both types of tools, spray buildup of the tool steel is rapid, taking only a matter of minutes.