The weld nut you're describing is known by several names, including "Flange Weld Nut - Projections Barrel Side" and "Round Base Projection T-nut." It features three spherical weld projections on the barrel side of its flange. These projections, along with a section of the base material, are joined together by melting them through the application of electric current, a process known as resistance welding. One of the key advantages of projection welding, which involves the resistance welding of these projections, is that it helps reduce surface marring on the base material.

The flange of these projection T-nuts serves multiple purposes. It provides additional bearing surface, enhancing structural integrity, and reducing the risk of rupture or pull-through in the parent material. These stamped and flanged weld nuts with projections on the barrel side are typically used in through-the-hole applications, where they provide a reliable and secure fastening solution.