Metal joining techniques Methods for assembling/disassembling products made from metal

Learning objectives To be aware of the need to join metal parts in a permanent or temporary fashion To be familiar with a range of permanent and temporary joining techniques. To be able to select an appropriate joining technique for a particular design situation

The requirement for joining, assembly and disassembly Metal products are often comprised of sub-assemblies joined together. It is not cost effective to produce metal products ‘carved’ from a single piece. Products made from metal are generally exposed to high wear and fatigue. Parts will wear and need to be replaced.

Permanent joining The product has no requirement to be disassembled Welding using combustible gas or electrical current Soldering using a secondary low-melting point metal Rivetting Adhesives/sealants

Welding Oxygen-Acetylene MIG-Metal with Inert Gas Arc/’Stick’ welding

Soldering Soft soldering PCB/Plumbing Silver soldering (ring) Brazing (bike)

Riveting Set rivets Spitfire fuselage Pop rivets Land rover body

Adhesives for metal Epoxy resin (Araldite, two-part thermoset) Polyurethane adhesive/sealant Lotus Elise Body tub

Non-permanent The product may need to be dismantled. Screw thread fastenings (sometimes called self-tapping screws) Machine thread fastenings (bolts and nuts) Pins and clips (often for retaining wheels)

Design considerations Does the product need to resist flexing? Will the product be under extreme load? Will vibration be an issue? Will the product incorporate wearing parts that will require replacement? Will the product be very large/heavy and need to be transported? Will the product be made from differing materials?

Click-view film ‘Joining Metals’ Make notes on the worksheet