Heating the part, often to about 90 to 150 °C, just before the first coating pass, usually with the gun itself making passes without powder or with a separate torch or oven. It removes condensed moisture and adsorbed contaminants and narrows the temperature gap between hot splats and cold metal, reducing interface stress. Too much preheat oxidizes freshly blasted surfaces, so it is kept short and controlled.
Two preheat passes with no powder, check it's at 200 F on the gun, then start the bond coat.
Also heard as
- preheating
- preheat passes
Related terms
Substrate temperature
The temperature of the part being coated, usually held below about 150 °C during spraying.
Bond coat
The first layer sprayed on a substrate to help the following coat stick and sometimes protect the metal.
Residual stress
Stress locked into a coating and substrate after spraying, from splat shrinkage, cooling and impact.