Metallics TEKD20B 12 x 3/4 in. 5/16 Indented Hex Head Self-Drilling & Tapping Screws with Washer - #3 Drill Point - Steel Zinc - Each

No. The TEKD20B is a Type BSD self-drilling and tapping screw, so the #3 drill point cuts its own hole and the UNC thread taps it in the same pass. Drill time runs about 2.5 seconds through a 1 mm plate at the rated minimum torque.

At 3/4 inch overall length with a #12 diameter, the TEKD20B suits thin stack-ups: a strap, clip or box flange against 0.110 to 0.210 inch steel. The drill point consumes part of that length, so if you are going through two thick members or a layer of insulation, order a longer self-drill in the same series.

The integral washer runs 0.398 to 0.432 inch outside diameter with a washer thickness of 0.022 to 0.039 inch, so it bears on a wider footprint than a plain hex head. That's the reason it's used for hanging straps, clips and sheet metal where a bare head would pull through. It's a bearing washer, not a sealing washer, so it won't gasket a wet exterior joint.

Torsional strength is 92 lb-in minimum and the screw is case hardened to Rockwell C32-40, made from AISI 1016-1024 steel. That's a standard duty self-drill, so use a depth-sensitive screw gun at controlled RPM; an impact driver well past 92 lb-in will twist heads off.

The TEKD20B is zinc plated carbon steel, silver in appearance. Zinc plating is a mild indoor and sheltered corrosion coating. For exterior exposure, roof work, coastal air or chemically damp plant areas, specify a stainless or coated exterior self-drill instead.

They ship boxed with a 5,000 piece order minimum, and the box runs 40.5 lbs. That's a stocking quantity for a shop or an MRO crib rather than a one-job buy. Other sizes and quantities can be quoted on request.