Gray fire doors (single-leaf, single-leaf with window, double-leaf, double-leaf with window) equipped with closers and rim locks are essential fire-protection products. Adhering to strict standards (BS 476, NFPA 80, GB 12955), their production ensures reliable fire resistance and durability. Below is the core process overview.
1. Raw Material & Precision Cutting
High-quality cold-rolled steel plates (0.8–1.2mm for leaves, 1.2–1.5mm for frames) are selected. Non-combustible core materials (honeycomb fire-retardant paper, perlite, rock wool) and accessories (gray electrostatic powder, fire-resistant glass, closers, rim locks) are prepared. CNC machines cut steel into door panels, frames and window blanks with high precision.
2. Forming & Window Processing
Hydraulic bending machines shape steel plates into door leaf cavities. Reinforcing ribs are stamped for structural stability. For window-type doors, CNC routers cut openings, and steel window frames are welded and polished. Heat-resistant fire glass is installed with fire-retardant sealant to prevent smoke penetration.
3. Core Filling & Accessory Assembly
Fire-retardant core materials are evenly filled into leaf cavities, then covered and fixed. Double-leaf doors are fitted with interlocking devices. Closers (top-mounted) and rim locks (side-mounted) are installed—closers ensure automatic tight closing, while rim locks enable stable locking and quick emergency opening. Fire-resistant hinges (3–4 per single leaf) are mounted for firm connection.
4. Gray Surface Treatment
Workpieces undergo degreasing, derusting and phosphating to enhance coating adhesion. Electrostatic powder spraying applies a uniform gray coating (60–80μm), followed by curing at 180–200℃ for 20–30 minutes, forming a smooth, high-temperature-resistant and corrosion-proof surface.
5. Quality Inspection
Dimension accuracy, fire resistance (sampling test), accessory functionality (closer/lock performance) and surface quality (no bubbles or uneven color) are inspected strictly to ensure compliance and appearance consistency.
Key Focus for Each Type
- Single-leaf: Balance to avoid closer deviation.
- Single-leaf with window: Precise opening size and tight window sealing.
- Double-leaf: Accurate interlocking device installation for tight closure.
- Double-leaf with window: Symmetrical window design for consistent look and performance.
