Projection weld
Applied to joint
Overlapping sheets — spot welds at interface
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Description
A resistance weld where a pre-formed projection (dimple or embossment) on one member localises the welding current. The projection collapses during welding, forming a weld nugget at the contact point. Allows precise weld placement and multiple simultaneous welds.
In plain English
Like a spot weld, but instead of relying on the electrode tips to localise the current, one of the sheets has a small raised dimple pressed into it. The current concentrates at that dimple, melts through, and forms the nugget. The arrow points to the sheet with the projection. The advantage is you can stamp multiple projections and weld them all at once in a single press stroke. Very common for welding nuts, bolts, and brackets to sheet metal in automotive and appliance work.
Symbol position
Circle on the reference line. ISO System A has a line through the top of the circle. Arrow points to the member with the projection.
Size notation
Weld diameter or projection diameter to the left. Pitch if in a pattern.
Notation examples
ISO System A adds a line extending from the top of the circle (distinguishing it from a spot weld). System B and AWS use the same circle as spot welding, relying on context and the arrow to distinguish. Minor visual difference.
Circle symbol. Arrow points to the member with the projection.
System A: circle with line extending from the top. System B: circle. Arrow points to projection sheet.
Common uses
- Weld nuts and weld studs on automotive panels
- Bracket-to-sheet metal attachments
- Multiple simultaneous welds in press tooling
- Appliance and electronics enclosure assembly
