New Energy Battery Housing Coating

Typical Working Conditions in This Industry

Battery housings (trays, top covers, lower housings) are characterized by:

• Insulation is a functional requirement, not an appearance requirement — insufficient film thickness directly causes the withstand voltage test to fail
• Deep structures with many internal cavities, plus areas such as sealing surfaces and threaded holes where powder must not be applied
• Large dimensions, often over 1 metre, requiring multiple guns for coverage
• Large batch volumes; parameter drift shows up concentrated in sampling inspection

Insulation Performance and Film Thickness

The film thickness requirement for an insulating coating is usually higher than for ordinary appearance parts. Common causes of insufficient film thickness:

Symptom	Possible cause
Overall film thickness low	Gun travel too fast, insufficient powder output
Local film thickness insufficient	Field shielding at deep cavity positions, gun distance too great
Edge film thickness insufficient	Faraday cage effect, voltage too low
Film thickness fluctuating	Unstable powder feed, powder has absorbed moisture

Recommendation: run a film thickness distribution test (multi-point measurement) before going on line to identify the thinnest positions, then add guns or adjust the gun travel path accordingly, rather than simply increasing overall powder output.

Masking and Protection

Critical areas on battery housings must be masked:

• Sealing surfaces (affect sealing performance)
• Threaded holes (affect assembly)
• Electrical connection surfaces (affect conductivity)
• Welded positions

Masking options include high-temperature tape, silicone plugs and dedicated masking fixtures. Although dedicated fixtures require higher initial investment, at large production volumes they are far more efficient than manual tape application.

Deep Cavity Structure Coverage

Deep cavities are the position the electrostatic field has the hardest time reaching.

Approaches:

1. Add gun positions at multiple angles to cover internal cavities from different directions
2. Rotate or turn the workpiece so internal cavity openings face the guns
3. Pre-spray station doing low-pressure coating on critical internal cavities
4. Where necessary, use a tribo gun or fluidized bed process for specific areas

Cleanliness Management

Battery workshops are sensitive to dust, and coating requirements and cleanliness requirements easily conflict.

• Provide independent partitioning and negative pressure in the coating area
• Match recovery system air volume to avoid powder escaping
• Clean powder build-up in the booth regularly, not only for appearance but also as a fire safety requirement

What We Need From You

• Housing dimensions, structure and critical insulation areas
• Target film thickness and withstand voltage test standard
• Masking requirements and current masking method
• Daily output and conveyor line type