Weld Screw
Screws · projection weld screw · stud screw · capacitor discharge screw
Definition: A weld screw has small projections under the head that are resistance-welded to sheet metal, providing a permanent male thread without a through-hole.
Anatomy
■ Head■ Shank■ Threads■ Point
Governing standards: Manufacturer specified (no universal standard)
Common Sizes
| Inch | Metric | Head width | Head height |
|---|---|---|---|
| #6-32 | M3.5 | — | 3/8 to 3/4 long |
| #8-32 | M4 | — | 1/4 to 1 long |
| 1/4-20 | M6 | — | 3/8 to 1-1/2 long |
Representative sizes. Full dimensional data lives in the standards listed below.
Grades & Strength
| Grade | Material | Tensile (psi) | Marking |
|---|---|---|---|
| Low carbon steel | steel | — | For resistance welding |
| Stainless | stainless steel | — | For stainless panels |
Materials
- Low carbon steel
- Stainless steel
Pros & Cons
Pros
- Permanent, strong attachment
- No through-hole or leak path
- No nut to reach behind
Cons
- Requires a projection welder
- Heat can distort thin sheet
- Not removable
Typical Uses
- Sheet-metal enclosures
- Appliance shells
- Automotive panels
- Electrical boxes
Alternatives & Related
Where to Buy
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FAQ
How is a weld screw attached?
Projection (resistance) welding passes current through the small projections under the head, fusing them to the sheet without burning through.
Weld screw vs weld stud?
A weld screw is small (under 1/4 in) with a screw head; a weld stud is a larger rod for heavier attachments.