Fabrication, Machining and Assembly Techniques
This domain covers how parts are made and joined. Fabrication includes marking out, cutting, bending, forming, and joining by welding, brazing, soldering, riveting and mechanical fasteners. Machining includes turning, milling, drilling, grinding and finishing, with attention to speeds, feeds, depth of cut and workholding. Assembly covers fits, fastening methods, torque, alignment and inspection.
Understand the difference between a permanent joint (weld, rivet, adhesive) and a temporary joint (bolt, screw, clamp). Know weld types (butt, fillet, lap, tee) and basic weld defects (porosity, undercut, slag inclusion, lack of penetration). Understand that brazing and soldering melt the filler but not the parent metal, whereas welding melts the parent metal.
Traps: confusing brazing with welding; assuming a fillet weld is a butt weld; forgetting that heat distortion occurs in welding and requires sequencing or jigs; and overlooking that a rivet joint is permanent while a bolted joint can be dismantled.
Rule of thumb: choose the joint by whether it must be permanent, the load type, and the materials. Worked example: joining two 2 mm aluminium sheets for a duct needs a low-heat method to avoid distortion; riveting or adhesive bonding is often preferred over welding, which can warp thin sheet without a jig.