Spray transforms model-making

Design engineers working on the development of new engine systems at Ford’s Engineering Research Centre in Dunton are becoming increasingly impatient, according to Richard Wooldridge, rapid prototyping supervisor. They want their models to look like the real thing, but are not prepared to wait while it is hand finished. Traditional paint methods take around five […]

Design engineers working on the development of new engine systems at Ford’s Engineering Research Centre in Dunton are becoming increasingly impatient, according to Richard Wooldridge, rapid prototyping supervisor.

They want their models to look like the real thing, but are not prepared to wait while it is hand finished.

Traditional paint methods take around five hours to give a model the metallic appearance of a cast engine block, using two coats of cellulose lacquer and allowing time for preparation and drying.

But a new metal spray technique means it can be done in around 30 minutes. Drying is immediate. And no special skills are needed to use the equipment.

Adjustment of the nozzle on a handheld gun changes the look of the model. A fine setting gives the appearance of diecasting while a coarser setting makes larger parts look as if they have been sand cast.

Low-melting point alloy specialist Mining & Chemical Products developed the process which puts a zinc alloy coating between 0.1mm and 0.2mm thick on to a variety of model substrates including plastics.

Heat damage is not a problem since the molten droplets, applied at 200 degrees C, are so fine they dry immediately on contact.

Ford uses the system to spray models made from laminated paper. A second coat smooths out ridges made by the laminated object modelling process.