Powder Coating Operating Guidelines and Coating Quality Control
Spray Gun Operating Posture
- Hold the spray gun handle with your right hand (index finger on the trigger), keeping your arm relaxed and avoiding hunching or excessive bending (to prevent fatigue and uneven coating).
- Keep the spray gun 15-25cm away from the workpiece surface (holding it too close can cause powder accumulation and dripping, while holding it too far can cause powder rebound and coating thinning). Keep the gun tip perpendicular to the workpiece surface at a 90° angle (holding it too far can cause "missing spray" or uneven coating thickness).
Spray Path and Technique Control
Path Planning:
- Follow the principle of "hard first, easy later; inside first, outside second; top first, bottom last"-prioritize spraying grooves, corners, and holes on the workpiece (these areas are prone to missed areas, so slow spray gun movement is recommended to ensure powder coverage), followed by spraying flat surfaces.
- For flat surface spraying, use a zigzag or parallel reciprocating spray path, with adjacent spray strips overlapping by 1/3 (to avoid "joint marks"). Maintain a movement speed of 20-30 cm/s (too fast and the coating will be too thin; too slow and the coating will be too thick and prone to dripping).
Avoid Common Problems:
- Corner "Powder Piles": When spraying workpiece corners, increase your spray speed (the electric field is concentrated at corners, causing powder to accumulate easily, resulting in "thick edges" after baking).
- Hole "Spray Missing": Aim the spray gun tip at the edge of the hole and tilt it slightly 5-10° into the hole (but avoid fully inserting it to prevent powder clogging the hole).
- Coating "Orange Peel": If the surface is uneven (orange peel), check whether the powder output is excessive, the atomizing air pressure is insufficient, or the powder has absorbed moisture (hygroscopic powder has poor flowability and tends to clump after atomization).
Static Electricity Safety and Emergency Response
Actions Not Allowed:
- Do not touch the spray gun tip while spraying (high voltage may cause electric shock) or point the spray gun at people or grounded metal objects (to avoid sparks from static discharge).
- If you need to adjust the workpiece position, first turn off the spray gun trigger and disconnect the power to the main unit before moving the workpiece (to prevent electric shock from live operation).
Emergency Procedure:
- If you experience a "gun leak" (numbness in your hand), immediately release the trigger, turn off the main unit power, and check for damage to the high-voltage cable.
- If the powder ignites unexpectedly (e.g., static electricity sparks igniting accumulated powder), immediately use a dry powder fire extinguisher (do not use water, as it will cause the powder to clump and may conduct electricity) to extinguish the fire, and activate the workshop exhaust system.
