Very common method. decent data sheets here:
formatting link
You can get them in all sorts of configurations. The ones I've seen used
most are square like an old fashioned stove bolt nut, have 4 projections
that make the high resistance contact with the base metal, and have a
protruding ring that centers the nut in the proper spot. See P/N WP2701
at Ohio Nut. For your 5/16" nuts the pilot hole would be 3/8". If the
base metal is already drilled, you can use the no shoulder version but
you need some sort of fixture to align the nut with the hole.
It does take a fairly decent sized spot welder. It's been a while so I'm
not sure on the minimum for your application. The spot welder setting is
quite critical to get a consistent weld. Too little heat and pressure
and the nuts break right off. Too much and the threads get crushed
and/or melted.
John Kish wrote:
> Does anyone out there have any expieriance welding (resistance welding?)
> nuts on to .083 sheet metal. Need to attatch 3600 5/16 nuts to some .083
> mild steel Stampings. Once had heard about something called projection
> welding where special nuts were manufactured with protrusions to assist spot
> welding of them . Trying to find some info or at least a dirrection to go >
>
>
> Thanks in advance
> John Kish
>
>
>
>