Designing Weld Nuts for Manufacturability
· 6 min read
PLACEHOLDER ARTICLE — replace before launch. This exists so the resources layout can be checked with real rendered content. Nothing below is reviewed technical guidance.
Weld nuts fail in predictable ways. Most of the failures we see on incoming quality reports trace back to a decision made long before the part reached a press: a projection height chosen for a different material thickness, or a thread class specified without reference to the mating fastener.
Projection geometry
Three projections is the default for a reason. It is the smallest number that defines a plane, so the nut seats flat against the panel without a fourth point fighting the other three. Adding a fourth projection does not improve seating; it introduces one.
The projection height should be set against the panel thickness rather than the nut body. A projection sized for 2mm sheet that lands on 1.2mm sheet will burn through before the weld nugget forms.
Material pairing
Carbon steel to carbon steel is forgiving. The pairings that need attention:
- Stainless to carbon steel, where the difference in electrical resistance shifts the heat balance toward the carbon side
- Coated panels, where the coating vaporises and carries weld metal with it
- Any pairing where one side is more than roughly twice the thickness of the other
Weld schedule
A schedule that works on a prototype cell rarely transfers unchanged to a production line. Tip wear, cooling water temperature, and secondary circuit length all move the delivered current. Qualify on the line that will run the job.
What to send with an RFQ
Send the panel material and thickness, the mating fastener, and the joint's load case. Those three determine most of the rest, and supplying them up front removes a round trip.