Materials Processing and Manufacturing
Solidification and casting
Understand nucleation and growth, dendrites and segregation, and riser design. Chvorinov's rule, t = B*(V/A)^2, says solidification time scales with the volume-to-surface-area ratio squared, so a riser must have a larger V/A than the casting it feeds. Compare sand, die, and investment casting for tolerance, surface finish, and cooling rate (which controls dendrite arm spacing and properties).
Deformation and joining
Rolling, forging, extrusion, and drawing all induce preferred orientation and residual stress and require annealing schedules (recovery, recrystallization, grain growth). For welding, know fusion-zone and heat-affected-zone behavior, the carbon equivalent for weldability, preheat and post-weld heat treatment, and characteristic HAZ problems such as sensitization or softening in cold-worked alloys. Powder metallurgy relies on powder character, compaction, and sintering densification.
Polymers and composites
Injection molding, extrusion, blow molding, and thermoforming for thermoplastics; hand lay-up, filament winding, and autoclave cure for composites. Watch shrinkage, warpage, and fiber orientation.
Surface engineering
Carburizing and nitriding (case depth, hardness profile), shot peening (compressive residual stress for fatigue), plating, and thermal spray.
Traps
Mixing V/A upside down; forgetting that faster cooling refines structure and raises strength; assuming a weld is as strong or as corrosion resistant as the base metal; ignoring residual stress from machining or quenching.
Worked example
A riser with V/A = 3 cm solidifies in 9 min with B = 1 min/cm^2. A nearby section with V/A = 1.5 cm takes only 2.25 min, so the riser stays liquid long enough to feed it. Rule of thumb: riser V/A must exceed the casting's V/A.