Manufacturing Processes and Production Engineering
What you must command
Casting (sand, die, investment), forming (forging, rolling, extrusion, drawing), joining (welding, brazing, soldering, riveting), machining (turning, milling, drilling, grinding) with cutting parameters, and metal cutting theory (tool geometry, chip formation, tool wear, Taylor's tool life). Also metrology and surface finish.
Traps that appear in questions
- Taylor's tool life: VTⁿ = C; n depends on tool material (about 0.1–0.15 for HSS, 0.2–0.4 for carbide).
- Cutting speed vs. spindle speed: V = πDN/1000 with D in mm gives m/min.
- MRR in turning = V × f × d (speed × feed × depth of cut).
- Casting defects: shrinkage cavity, blowhole, cold shut - match the defect to its cause.
- Welding symbols: the arrow side vs. other side determines where the weld is placed.
- Gating: sprue is tapered to maintain flow; riser feeds shrinkage.
Worked rule of thumb
For turning with D = 80 mm, N = 500 rpm, feed f = 0.2 mm/rev, depth d = 2 mm: V = π × 80 × 500/1000 ≈ 125.7 m/min; MRR = 125.7 × 1000 × 0.2 × 2 mm³/min ≈ 50 265 mm³/min (about 50 cm³/min). Check: V in m/min times 1000 gives mm/min, times feed and depth in mm gives mm³/min.
For tool life, if VT^0.25 = 200 and V doubles, tool life falls by 2⁴ = 16 times. This exponent logic answers many questions without full calculation.