Weld nuts are installed on steel plates or sheets to provide firm, fixed threads for a mating screw or bolt. They are welded around holes that have been punched or drilled into the metal. They generally have a flange with small nubs that melt to form the weld. Weld nuts are used heavily in the automobile, appliance, consumer products and medical equipment industries.
The fasteners are typically welded to parts using a semiautomatic cell equipped with a fixture designed specifically to hold the part and nuts in position. The operator takes a part out of a bin, loads it in the fixture, steps back and hits two safety buttons. With the operator out of the way, the machine clamps the part in place. The operator then walks forward, takes nuts out of a bin, and loads them into position on the fixture. After loading the nuts, the operator again steps back to press the safety buttons, and a resistance welder is activated to weld the nuts to the part.