Joining
Riveting vs Welding
Riveting joins sheets mechanically with a deformed fastener through a lap joint; welding fuses the metals into a continuous joint. The core trade: rivets handle dissimilar, coated, and heat-sensitive materials with easy inspection, while welds give higher joint efficiency, sealed seams, and near-zero fastener cost at volume.
| Riveting | Welding | |
|---|---|---|
| Joint efficiency | 60 to 75% of base sheet strength | 85 to 100% with full penetration |
| Cycle time per joint | 1 to 3 s blind rivet, 1.5 s SPR | 1 to 3 s spot weld, arc seams slower |
| Dissimilar and coated stock | Aluminum to steel, pre-painted, composites OK | Poor: coating burn, brittle intermetallics |
| Heat input and distortion | None, no HAZ | HAZ softening, distortion on thin sheet |
| Inspection | Visual plus set-head check | Peel test, ultrasonic, or teardown NDT |
| Consumable cost | $0.03 to $0.30 per rivet | Near zero for spot, wire $2 to $5/lb for arc |
| Weight and sealing | Adds fastener mass, needs sealant to seal | Continuous welds seal, no added mass |
Choose Riveting when
- Mixed materials: aluminum body panels to steel, sheet to composite
- Pre-painted or galvanized stock where heat wrecks the coating
- Field assembly and repair where weld power and NDT are impractical
Choose Welding when
- High-volume steel assemblies where per-joint cost must drop below $0.02
- Sealed or pressure-tight seams: tanks, enclosures, frames
- Maximum joint strength and stiffness with no added fastener weight
The verdict
In high-volume steel, spot welding wins on cost and stiffness, which is why car bodies carry 3,000 to 5,000 spot welds. Choose riveting for aluminum-intensive or mixed-material structures, coated sheet, and anywhere heat distortion or weld inspection cost outweighs the $0.05 to $0.30 per fastener.
Cost comparison
A pneumatic rivet gun costs $200 to $1,500 and blind rivets run $0.05 to $0.30 each; automated self-piercing rivet systems cost $50,000 to $150,000 with rivets at $0.03 to $0.08. Resistance spot welding cells run $30,000 to $120,000 but consume no fastener, so per-joint cost falls under $0.02 at volume. Welding wins the crossover on high-volume steel; riveting wins whenever fastener cost is cheaper than the coating repair, distortion rework, and NDT a weld would trigger.
Common questions
Why did aluminum car bodies move to self-piercing rivets?
Resistance spot welding aluminum needs 2 to 3x the current of steel, eats electrode caps every 20 to 50 welds, and joining aluminum to steel by fusion creates brittle intermetallics. SPR joins the stack cold in about 1.5 s with fatigue life often better than spot welds, at $0.03 to $0.08 per rivet.
Are riveted joints weaker than welded joints?
Typically yes in static strength: rivet holes cut section area, so joint efficiency runs 60 to 75% versus 85 to 100% for good welds. But rivets avoid HAZ softening, which in 6xxx aluminum can knock 30 to 50% off local strength, and riveted lap joints often show better fatigue behavior.