How Are Light Bulbs Made? The Fascinating Answer!

We’ve come a long way since Edison’s first short-lived light bulbs from 1879, as both designs and production processes evolved to illuminate every corner of the globe. Now, automated systems allow us to make over 2 billion light bulbs yearly in the U.S. alone!

With that level of manufacturing efficiency, it’s easy to assume that incandescents are still straightforward to produce. But while screwing in a light bulb may be simple, its creation results from complex and precise sequences paired with the intelligent use of finite resources. Let’s explore how manufacturers take those raw materials and turn them into the light bulbs we use today.

Materials Used in Light Bulbs

Incandescent light bulbs consist of three primary components: the glass case, the base, and the filament. Each piece includes raw materials to improve cost-efficiency, lifespan, and performance.

Glass Case

Filament

Base

How Light Bulbs Are Made

Light bulb manufacturing involves separate production processes to make individual parts, namely the glass case and the electrified mount. After forming these two components, the assembly sequence merges them to complete the bulb.

Making the Mount

Light bulbs begin as glass tubes cut to specific lengths. A glazing wheel heats the end of each piece enough to smooth the edge. Next, another machine heats one end of the tube and forms it into a flared shape.

Two copper lead wires fit into the flared end of the glass tube. An exhaust tube follows, inserted snugly between the leads. A series of burners soften the other end of the glass tube so a press machine can mash it together, locking the lead wires into the glass. The press also punches a small hole to exhaust air from the bulb later in the process.

The mount progresses through several shaping machines that separate, bend, and hook the lead wires to hold the filament. A liquid zirconium coating along the wires improves their lifespan by making them more moisture-resistant.

Two filaments of different wattages produce three layers of light in a three-way bulb. For instance, a bulb may include a 50-watt filament for low light and a 100-watt filament for brighter light. Both could then combine for a 150-watt ultra-bright light.

Making the Bulb

Melted glass runs through a ribbon machine with air nozzles that blow it into the rounded light bulb shape. A stamping machine applies the manufacturer logo, wattage, and voltage information. The bulbs may then run through a coating machine that applies a thin layer of silicone to the inside of the glass, making it opaque.

Combining the Pieces

The mount inserts into the bulb in a machine that melts the flared end of the mount tube to the bulb. While malleable at high heat, the neck of the bulb passes through a press that forms the shape of the aluminum shell that will come later.

A vacuum sucks all of the air out of the light bulb and replaces it with argon gas. The filament’s tungsten atoms heat to 4,000 degrees, producing incandescent light. At those temperatures, oxygen in a bulb would combust and damage the filament. By replacing air through the mount’s exhaust tube with argon gas, which doesn’t combust, the filament will last much longer. A torching device seals the glass to contain the argon gas, keeping the ends of the lead wire exposed on the exterior of the case.

An aluminum base fits over the light bulb’s molded glass end. A welding machine solders one lead wire to the end of the base and spot welds the other to the side of the aluminum casing, creating two contact points for the electrical current.

After production, light bulbs progress through a series of tests with progressive lighting intensities. Testing the bulbs is necessary to strengthen the filament to prevent shipping damage.

LED Light Bulbs

Incandescent light bulbs may have been the prototypical lighting option for over a century, but regulatory changes in the early parts of the 2010s have significantly changed the market in a short time. While only 4% of households used LED light bulbs in 2015, that rate jumped to nearly 50% in only 5 years.

Meanwhile, incandescent, halogen, and compact fluorescent glass bulbs followed a steady decline, which will only worsen as the federal government tightens energy efficiency standards. Eventually, incandescent and halogens will be on the way out entirely.

As they use up to 90% less energy than incandescent and last up to 30 times longer, the logic of moving to LEDs is unquestionable. In design, the bulb is relatively simple. An LED board sits at the end of the base, with each diode emitting white light.

LED lights are directional, creating a spotlight-like effect when uncovered. A diffusing case spreads the light in a way more similar to a traditional bulb. Unlike incandescent and similarly used CFL bulbs, which release energy primarily as heat, ultra-efficient LEDs only produce light. Rather than rely on fragile yet heat-resistant glass, manufacturers can now use shatter-resistant plastic or epoxy resin to make the bulb.

With an electronic board controlling the LED lights, these bulbs also allow for the efficient addition of smart functionality. An internal computer can change brightness levels for simple dimming, but now you can even manipulate the color temperature to change the mood of a room.

Final Thoughts

Light bulb manufacturing processes have advanced to an incredible degree in the past century despite the concept remaining relatively unchanged. And with incandescents on the way out in 2023, the next evolution in lighting has arrived. Replacing the simple circuitry of incandescent is redefining how light bulbs are made and, thanks to built-in computer technology, revolutionizing how we light our world.

Featured Image Credit: Antoni Shkraba, Pexels