Metallics QK515M 8 x 1/2 in. 1/4 Hex Head Slotted Sharp Point Self-Piercing & Tapping Screws - Steel Zinc - Each

That's the point of the Metallics QK515M. It's a sharp point self-piercing and tapping screw, so it pierces and forms its own thread in thin sheet stock without drilling first. Twin lead threads cut the driving torque, so it starts and runs faster than a standard tapping screw. At 1/2 inch long it's for thin-gauge work, not heavy plate.

Either works. The QK515M has a 1/4 inch hex washer head with a slot cut into it, so a 1/4 inch nut driver or hex socket seats on the head, and a flat blade fits the slot for hand work in tight spots. Head width measures 0.244 to 0.25 in. and head height 0.096 to 0.11 in. The slot runs 0.045 to 0.054 wide and 0.052 to 0.074 deep, so a standard cabinet-tip flat blade engages it.

Case hardness runs Rockwell C28-38 on AISI 1018 to 1022 carbon steel, which is what lets the sharp point punch and form thread rather than deform. The finish is zinc plated steel. Zinc plating is an indoor and protected-location coating; for sustained exterior exposure or wet locations, spec a stainless or hot-dip fastener instead.

They go out in a box of 15,000, which is the order minimum. That's bulk quantity for a shop or a fleet job, not a handful for one panel. If you need a different size or a different count, Metallics offers other sizes and quantities in the JQK line by request.

The washer is integral. The head carries a washer face measuring 0.322 to 0.348 in. outside diameter with a washer thickness of 0.019 to 0.031 in., so it spreads bearing load over thin sheet without a separate washer in the bag. There's also an undercut beneath the head, which gives you more usable thread engagement in the material.

15 threads per inch on the #8 diameter. That's a coarse pitch, which is what you want in light-gauge steel and thin sheet: fewer, deeper threads bite into material that can only support a thread or two of engagement. Paired with the twin lead thread form, it starts square and pulls in quickly.

Both are flagged compliant on the QK515M record: ARRA compliant and Buy American compliant. Country of origin is listed as multiple, so if your specification requires documentation naming a single origin country for the lot you receive, request it against the shipment.

Head dimensions on self-piercing screws are not the same as on standard tapping screws, and there is no single industry standard governing self-piercing screw head geometry. Metallics publishes the QK515M head as 0.244 to 0.25 in. wide and 0.096 to 0.11 in. high as a guide, with deviation possible. If your assembly depends on a precise head profile, work to those ranges rather than to a standard tapping screw table.