Manufacturing Processes (Mech)

Casting:

• Sand casting: molten metal poured into sand mold. Most common.
• Die casting: under pressure; high accuracy.
• Investment casting (lost-wax): wax pattern; high precision.
• Centrifugal casting: for cylindrical parts.

Defects: shrinkage, porosity, hot tears, cold shuts.

Welding:

• Arc welding: electrical arc between electrode + workpiece. SMAW, MIG, TIG.
• Gas welding: oxy-acetylene flame.
• Spot welding: resistance welding for sheets.
• Brazing: filler with melting point < base metal.
• Soldering: lower temp, for electronics.

Machining:

• Turning: lathe; cylindrical parts.
• Milling: rotating cutter; flat surfaces, slots.
• Drilling: holes.
• Grinding: finishing, high accuracy.
• CNC: computer-controlled. Modern industry.

Cutting tools:

• HSS (high-speed steel), carbide, ceramics, diamond.
• Tool life: Taylor's formula VT^n = C.

Forming:

• Forging (hot), rolling (sheets, bars), extrusion (pipes), drawing (wire).
• Sheet metal: punching, blanking, bending.

Powder metallurgy: mix powders → press → sinter.

3D Printing / Additive Manufacturing:

• FDM, SLA, SLS technologies.

Measurement tools:

• Vernier caliper (least count 0.02 mm).
• Micrometer (least count 0.01 mm).
• Dial gauge.

RRB JE focus: identify processes, basic measurement, common defects.