Flame spraying troubleshooting

1. Poor preparation of the surface (oxidized or oily surface)
2. Required surface roughness is >Ra 5
3. Too low preheating temperature
4. Too high preheating temperature

Clean the surface well
Sand blast well
Preferable >Ra10
Increase preheat
Decrease preheat

1. Overheating
2. Too fast cooling
3. Hardened base material

Slower cooling / controlled cooling

1. Poor preparation of the surface

2. Incorrect spray parameters
3. Incorrect spray distance
4. Poor sealings in the gun
5. Incorrect particle distribution for the gun
6. Too high oxygen level in the powder /oxidized powder
7. Powder contains hollow particles

Clean the surface well. 
Sand blast well.
Adjust parameters
Adjust distance
Replace seals
Choose the right parameter
Adjust lambda
Replace powder