Angle at which the gun axis meets the part surface. Coatings are densest and best bonded when particles hit square on; as the angle drops below roughly 60 degrees, splats smear, shadowing increases and porosity, oxide and roughness rise. Robot programs keep the gun normal to curved surfaces, and specs set a minimum angle for features that cannot be sprayed head-on.
You're at 40 degrees in that fillet, the spray angle's too shallow, the coating there will be junk.
Also heard as
- impingement angle
- gun angle
Related terms
Standoff distance
The distance from the gun exit to the surface being sprayed, which sets how hot and fast particles arrive.
Line of sight
The limit that thermal spray coats only surfaces the gun can point at directly.
Porosity
The fraction of a coating's volume made of voids between and within splats, usually reported in percent.