Page 29 - Manufacturing Engineering and Technology - Kalpakjian, Serope : Schmid, Steven R.

Section I.1 What Is Manufacturing?

Filament

Filling gas pp
'ii Support wires

Lead-in wires Button to hold support wires
Heat-deflecting disc used in
iii' lower portions from excessive heat
l
high-wattage lamps to protect

Stem press
Exhaust tube ’,.: circuit if an arc or short occurs, thereby
Fuse, which melts and opens the
preventing the bulb from cracking
-“VI
Base

FIGURE l.2a Components of a common incandescent light bulb. Source: Courtesy of
General Electric Company.

-1

~'
‘ gl lllslt
flat!

‘”`
Q

1 2 3 4 5 6
(bl

FIGURE l.2b Manufacturing steps in making an incandescent light bulb.
Source: Courtesy of General Electric Company.

tantalum. However, none of these materials has the wires. The filament is made by powder metallurgy
strength, resistance to high temperature, and long life techniques (Chapter 17), which involves first pressing
as has tungsten (Section 6 .8.3), which is now the most tungsten powder into ingots and sintering it (heating
commonly used filament material. it without its melting). Next, the ingot is shaped into
The first step in manufacturing a light bulb is round rods by rotary swaging (Section 14.4) and then
making the glass stem that supports the lead-in wires drawing it through a set of dies into thin wire (Sec-
and the filament and connects them to the base of the tions 15.8 and 15 .10). The wire diameter for a 60-WL
bulb (Fig. I.2b). All these components are positioned, 120-V bulb is 0.045 mm (().()018 in.). The diameter
assembled, and sealed while the glass is heated by gas must be controlled precisely, because if it is only 1 % less
flames. The filament is then attached to the lead-in than the diameter specified, the life of the bulb would be