Lecture Notes on Incandescent Light Bulb Production

Overview of Incandescent Light Bulbs

• Simple device with two metal contacts in the base.
• Contains a metal filament that emits light when heated.
• Electric current causes electrons to collide with filament atoms, vibrating them and producing heat (up to 4000°F).
• Heat causes the filament to emit visible light.

Production Lines in a Light Bulb Factory

• Two main production lines that merge:
  1. Glass Bulb Preparation
  2. Mount Creation (electrical components)

Glass Bulb Preparation Process

• Cutting Tubes: Glass tubing cut to specific lengths.
• Glazing Wheel: Tubes pass through a gas flame to smooth the surface (7 seconds).
• Flare Making: Heating the tube until malleable; one end is stretched into a flare shape.

Mount Creation Process

• Lead Wire Insertion: Two copper lead wires inserted into the flared end.
• Exhaust Tube Addition: A thin glass cylinder is inserted for air removal.
• Air Removal: A tiny hole is made for air to exit via the exhaust tube.
• Wire Separation: Lead wires are separated and formed into hooks to attach to the tungsten filament.
• Zirconium Coating: Lead wires coated with zirconium to resist moisture, extending lifespan.

Glass Properties

• Bulbs made from inexpensive soda lime glass.
• Each bulb is stamped with voltage, wattage, and company logo.

Opaque Light Bulbs

• Clear bulbs with a coating of synthetic silica (white powder).
• Coating process:
  • Bulbs charged to 30,000 volts.
  • Heat makes powder cling and removes moisture/impurities.

Merging Production Lines

• Bulb and mount merge for final construction:
  • Torches fuse the flared end of the mount to the neck of the bulb.
  • Neck molded to fit into the aluminum base.
• Air Replacement: Vacuum removes air and replaces it with pressurized argon gas to help filament resist heat.
• Sealing: Exhaust tube sealed to lock gas inside.

Final Assembly

• Base Creation: Aluminum base is prepared.
  • Lead wires inserted and soldered.
  • Spot welding completes the connection to base sockets.

Quality Control

• Flash Testing: Bulbs undergo repeated light-ups with higher voltage to strengthen filaments, reducing breakage during shipping.