Metallics TEKD55M 10 x 1/2 in. 5/16 Indented Hex Head Self-Drilling & Tapping Screws with Washer - #2 Drill Point - Steel Zinc - Each

The Metallics TEKD55M is rated for panel thicknesses of 0.035 to 0.110 in. That covers typical 20 gauge through roughly 12 gauge steel studs, strut, and sheet metal enclosures. Go thicker than 0.110 in. and the #2 drill point will not clear the hole before the threads engage, so you want a heavier drill point for that.

At 1/2 in. of length with 16 threads per inch, the TEKD55M is sized for single layer sheet and thin plate work in the 0.035 to 0.110 in. range, which is where most electrical box, strut, and stud fastening sits. If you are stacking two members or going through anything that puts total grip beyond about 1/2 in., step up to a longer screw in the same series so you get full thread engagement past the panel.

No. The TEKD55M is a Type BSD self-drilling and tapping screw with a #2 drill point, so it cuts its own hole and forms its own thread in one operation within the 0.035 to 0.110 in. panel range. Dropping the pilot drill step is the whole point of the design and it is why these go in fast on repetitive sheet metal fastening.

A 5/16 in. hex driver. The head measures 0.305 to 0.312 in. across the flats and 0.34 in. across the corners, so a standard 5/16 magnetic nutsetter in a drill or impact seats it. The drive is hex only, no slot or Phillips cross recess to strip.

Yes, it is a hex washer head design with the washer integral to the head. Washer outside diameter runs 0.384 to 0.414 in. with a 0.019 to 0.031 in. thickness. That bearing surface spreads load on thin sheet and helps keep the screw from pulling through light gauge panel, so you do not need to add a separate washer.

These are AISI 1016 to 1024 steel with a zinc plated finish. Zinc plating is a mild, indoor-duty coating. It is fine for conditioned space, ceiling grids, panel work, and dry mechanical rooms. For exterior exposure, roof work, or washdown and coastal environments, specify a stainless self-drilling screw instead rather than plated steel.

The TEKD55M is flagged compliant for both ARRA and Buy American, which is what a government, school district, or federally funded job usually asks for at submittal. Country of origin is listed as multiple, so if your specification requires a single named origin on the certification, state that requirement with the order.

Torsional strength is 61 lb-in minimum on the TEKD55M, with case hardness at Rockwell C32-40. Set your impact or drill clutch below that and the point will drill and tap in one pass. Metallics notes drill time of about 2.5 seconds through a 1 mm plate, and that minimum torque figures are the same for steel and stainless self-drill screws.

They ship boxed with a 5,000 piece minimum. That is a stocking quantity for an electrical contractor or MRO crib doing repeat panel and strut work, not a handful for one repair. The packed box weight is listed at 22.76 lbs.

Head height is 0.105 to 0.12 in., plus the integral washer at 0.019 to 0.031 in. thick. Figure roughly an eighth of an inch of profile above the panel. Worth checking if you are fastening behind a cover plate, inside a trim channel, or anywhere a flush surface has to sit over the fastener.