China Screw supplier---DAZHE Fastener
The hex washer head or hex flanged head self tapping screws also called roofing screws, with an additional metal washer bonded with EPDM washer, often used in fixing the corrugated roofing profiles to a wood or metal support in structure construction. Transhow Screw Factory produce and supply wide range of this kind of roofing screws both in standard specifications and also customized sizes.
The roofing screws are cold formed from C1022 low carbon steel with heat treatment. It can also be cold formed from SS410 and other fine material. The drilling head performs well in a 1.5mm to 5mm thickness object. The additional washers always in 16mm and 19mm diameter, its a steel galvanized washer bonded with EPDM or rubber washer that helps to fixing the roofings and also avoiding any leakage from the screwed holes. Standard available specifications are from #8 to #14 (thread diameter 4.2mm to 6.3mm) with the screw length from 13mm to 150mm (not including hex flange head length).