The quality of a steel fire shutter starts with the slats and the header. Here are the key requirements based on manufacturing standards and field experience in Dongguan.
Slat Quality
Material should be cold-rolled steel grade Q235 or equivalent, minimum 1.2mm thick for standard applications and 1.5mm or more for large openings or high wind load areas. The surface must be smooth — no rust, no scale, no obvious scratches or dents. Coating should be uniform, with good paint adhesion. Slat width tolerance must be within plus or minus 0.5mm, with consistent interlocking profile so slats engage smoothly without binding.
For composite slats with insulation inside, the insulation must fill the cavity completely — voids create hot spots. The two steel faces should be mechanically joined, not just glued: mechanical fasteners or crimped edges are better.
Header Quality
The header is the structural frame at the top of the opening, supporting the shaft, curtain, and housing. It takes the most load in the system. Material should be steel channel or formed plate, minimum 3mm thick for standard doors and 5mm or more for heavy doors. All header joints must be fully welded — not tacked. Welds should be ground smooth and painted with no porosity or undercut.
The motor support plate and bearing plate must be welded to the header, not bolted — bolts can loosen from vibration. Support plates must be perfectly aligned so the shaft runs true. Before leaving the factory, check the header assembly for squareness, weld quality, and dimensional accuracy. An off-square header makes every subsequent installation step harder.