Rationale For the proposed Changes: Production and manufacture of steel tapping screws has progressed considerably over recent years. Because of these developments, the standard doesnt represent state of the art in screw fastener production. Over thirty years of experience in screw fastener production has shown that a proper heat treatment for the hardening process is much more important than the raw steel material used. With a reduction of the core hardness and an increase of the surface hardness a significant improvement in screw ductility is obtained and the overall performance of the screw fastener is also improved without any negative impact on the load bearing characteristics. The requirement for minimum Grade 1018 is a carry over from SAE J78, which has not been modified to keep pace with the evolving screw fastener industry. Furthermore, the screw fasteners are required to be tested in accordance with the AISI test standards as the manufacturer must provide strength tests per AISI S904 as part of load calculation. This requirement in addition to the drill drive, drill capacity and torsional tests required by the standard create a substantial amount of Quality Assurances that the final product will perform well in cold-formed steel framing connections. Therefore, as long as the screw fastener meets the other requirements of the standard and AISI S904 testing is required for connection load calculations, the minimum grade and minimum core hardness requirements for self-drilling tapping screws should not be required.
Keywordsbugle head; crest; hex washer head; modified truss; pancake head; pan head; root; screws; self-drilling; self-piercing; spin-out; wafer head drill capacity; Cold-formed steel framing materials/applications; Bugle head screw; Hex washer head; Pancake head; Self-drilling/piercing screw; Steel screws--specifications; Wafer head drill capacity;
Draft Under Development