Manufacturing processes and joining techniques
What the domain tests
Manufacturing processes and joining techniques tests how a product moves from material to finished item. Questions cover cutting and shaping, forming, casting and moulding, jigs and fixtures, tolerances, quality control, and permanent or temporary joints. You must select a process for the material, quantity and required accuracy.
Core rules and concepts
- Choose the process for the batch size: hand tools suit one-offs; jigs and fixtures improve repeatability; moulding suits larger batches.
- A tolerance is a permitted variation; a clearance hole is larger than the fastener, while a tapped hole is threaded to match a screw.
- Temporary joints-bolts and screws-allow dismantling; permanent joints include rivets, welding, brazing, soldering and most adhesives.
- Prepare surfaces before adhesive bonding: clean, abrade and degrease. Clamp until cured.
- Wood joints: butt joints need reinforcement; dowels, biscuits and mortise-and-tenon increase glue area and location. Metal joints must consider thermal distortion and galvanic corrosion.
- Finishing protects and improves appearance; prepare before coating.
Worked example
For a permanent lap joint in 1 mm aluminium sheet, rivets are suitable: mark and drill matching holes with clearance, deburr, apply sealant, clamp, insert rivets and set them with a rivet gun. Adhesive alone may peel under load; welding thin sheet risks distortion and needs skill; bolts would need access and add weight. The reasoning is that the joint matches thin sheet, avoids high heat and can be inspected. Sealant reduces water entry and helps limit corrosion at the joint.
Traps that cost marks
Bonding an oily surface, drilling the wrong rivet clearance, overtightening screws, mixing dissimilar metals without isolation, or ignoring thermal movement all lose marks. A joint that is strong but cannot be assembled or maintained is not a good manufacturing choice.