Gap between the gun nozzle and the substrate, typically around 75 to 150 mm for plasma, 150 to 400 mm for HVOF and 100 to 200 mm for arc spray. It controls how long particles heat and accelerate, and whether they arrive molten or already cooling. Too short overheats the part and coating; too long gives unmelts, oxides, low deposition efficiency and higher porosity.
Standoff distance on the robot path drifted to 7 inches on the big end, that's why the DE dropped.
On long or curved parts check standoff at both ends of the robot path; a part a few millimeters off center changes particle state from one end to the other.
Also heard as
- spray distance
- standoff
- gun-to-work distance
Related terms
Spray angle
The angle between the spray jet and the surface, ideally 90 degrees for the densest coating.
Deposition efficiency
The percentage of the feedstock sprayed that actually ends up as coating on the part.
Cook
Booth slang for overheating a part during spraying, usually from slow traverse, short standoff or no pauses.
Running hot
Booth talk for parameters that are overheating the particles or part; running cold is the opposite.