Basic constraint of thermal spray: particles travel in straight lines, so bores, deep pockets, sharp internal corners and the backs of features only get coated if a gun can face them at a usable angle and distance. Small inside diameters need special extension guns, and parts with complex shapes may need multiple setups or a different process such as plating or diffusion coating.
That bore is only 1.5 inches deep and 1 inch wide, it's out of line of sight for anything we've got.
Check bore size and depth against the smallest gun in the shop before quoting ID work; extension guns have their own limits on thickness and quality.
Also heard as
- line-of-sight process
- shadowing
Related terms
Spray angle
The angle between the spray jet and the surface, ideally 90 degrees for the densest coating.
Masking
Covering areas of a part that must not be blasted or coated, using tapes, plugs, shields or maskants.
Standoff distance
The distance from the gun exit to the surface being sprayed, which sets how hot and fast particles arrive.