Welding suits permanent, stiff and continuous joints; riveting suits sheet assemblies, blind access or heat-sensitive parts; bolting suits removable, serviceable and field assemblies. Decide by load path, fatigue, sealing, thermal distortion, access, material combination and life-cycle cost—not fastener price alone.
Values in this article support engineering screening during design review, RFQ and prototyping. They do not replace formal calculations, material data sheets, qualified procedures or contractual standards.
LOAD TRANSFER
A weld transfers load through fused material; for an equal-leg 45° fillet, effective throat is approximately a=0.707z, but effective length, ends, direction and code factors still govern design. Riveted/bolted joints require checks for fastener shear, bearing, net-section rupture, edge tear-out and plate bending. Preloaded slip-resistant bolts also rely on interface friction and must not be treated as ordinary bearing bolts.
RAPID SELECTION
- Equipment enclosure: for serviceable thin sheet, screws plus self-clinching nuts often beat full welding. - Sealed box: continuous welding can seal but needs distortion/leak control; gasketed bolts ease service. - Aluminum panel to steel frame: isolated mechanical fastening avoids metallurgical incompatibility and reduces galvanic corrosion. - Blind-side access: blind rivet or rivet nut, after validating grip range, hole and spin resistance. - High vibration: first design sufficient preload and a non-slipping joint, then select locking features.
PROJECT CHECKLIST
Static/fatigue load; removal cycles; one/two-side access; sealing; heat effect; dissimilar metals; finish; inspection and service.