One-hundred-and-thirty years back, Thomas Edison completed the very first successful sustained test of the incandescent bulb. With a few incremental improvements in the process, Edison’s basic technology has lit the world ever since. This is going to change. We are on the cusp of a semiconductor-based lighting revolution which will ultimately replace Edison’s bulbs with a a lot more energy-efficient lighting solution. Solid state LED lighting will ultimately replace almost all of the hundreds of huge amounts of incandescent and fluorescent lights in use around the globe today. In fact, as a step along this path, President Barack Obama last June introduced new, stricter lighting standards that can support the phasing out of incandescent bulbs (which already are banned in parts of Europe).
To know just how revolutionary china LED power are in addition to why they may be still expensive, it is instructive to check out the way they are produced and also to compare this towards the manufacture of incandescent light bulbs. This article explores how incandescent lights are produced and then contrasts that process with a description from the typical manufacturing process for LED lights.
So, let’s start with examining how traditional incandescent lights are manufactured. You will see that this can be a classic example of an automated industrial process refined in over a century of expertise.
While individual incandescent bulb types differ in size and wattage, every one of them possess the three basic parts: the filament, the bulb, and also the base. The filament is made of tungsten. While very fragile, tungsten filaments can withstand temperatures of 4,500 degrees Fahrenheit and above. The connecting or lead-in wires are generally made from nickel-iron wire. This wire is dipped in to a borax solution to have the wire more adherent to glass. The bulb itself is made of glass and possesses a mixture of gases, usually argon and nitrogen, which boost the lifetime of the filament. Air is pumped out from the bulb and substituted with the gases. A standardized base supports the entire assembly in position. The base is known as the “Edison screw base.” Aluminum is utilized on the outside and glass utilized to insulate the inside the base.
Originally created by hand, bulb manufacturing is now almost entirely automated. First, the filament is manufactured employing a process called drawing, in which tungsten is blended with a binder material and pulled through a die (a shaped orifice) right into a fine wire. Next, the wire is wound around a metal bar referred to as a mandrel in order to mold it into its proper coiled shape, and then its heated in a process referred to as annealing, softening the wire and makes its structure more uniform. The mandrel will then be dissolved in acid.
Second, the coiled filament is connected to the lead-in wires. The lead-in wires have hooks at their ends that are either pressed on the end in the filament or, in larger bulbs, spot-welded.
Third, the glass bulbs or casings are produced utilizing a ribbon machine. After heating in a furnace, a continuous ribbon of glass moves along a conveyor belt. Precisely aligned air nozzles blow the glass through holes in the conveyor belt into molds, creating the casings. A ribbon machine moving at top speed can produce greater than 50,000 bulbs per hour. Following the casings are blown, they may be cooled then cut from the ribbon machine. Next, the inside the bulb is coated with silica to remove the glare the result of a glowing, uncovered filament. The label and wattage are then stamped to the outside top of each casing.
Fourth, the lower bulb can also be constructed using molds. It is made with indentations inside the shape of a screw so that it can easily squeeze into the socket of any light fixture.
Fifth, when the filament, base, and bulb are made, they are fitted together by machines. First, the filament is mounted to the stem assembly, using its ends clamped for the two lead-in wires. Next, the environment inside the bulb is evacuated, and the casing is full of the argon and nitrogen mixture.
Finally, the base and the bulb are sealed. The base slides on the end of the glass bulb to ensure that hardly any other material is necessary to have them together. Instead, their conforming shapes enable the two pieces to get held together snugly, with all the lead-in wires touching the aluminum base to make certain proper electrical contact. After testing, bulbs are put in their packages and shipped to consumers.
Bulbs are tested for lamp life and strength. In order to provide quick results, selected bulbs are screwed into life test racks and lit at levels far exceeding normal. This supplies a precise measure of how long the bulb can last under normal conditions. Tests are performed whatsoever manufacturing plants in addition to at some independent testing facilities. The average life of the standard household bulb is 750 to one thousand hours, based on wattage.
LED bulbs are made around solid-state semiconductor devices, therefore the manufacturing process most closely resembles that utilized to make electronic goods like PC mother boards.
A mild-emitting diode (LED) is actually a solid state electrical circuit that generates light from the movement of electrons in a semiconductor material. LED technology has been available since the late 1960s, but for the first 4 decades LEDs were primarily utilized in electronics devices to replace miniature lights. In the last decade, advances inside the technology finally boosted light output high enough for LEDs to begin with to seriously contend with incandescent and fluorescent light bulbs. As with many technologies, as the expense of production falls each successive LED generation also improves in light quality, output per watt, as well as heat management.
The computer industry is well suited to manufacture LED lighting. The process isn’t a whole lot distinct from building a computer motherboard. The businesses making the LEDs themselves are generally not in the lighting business, or it is a minor a part of their business. They tend to be semiconductor houses which can be happy cranking out their product, which is why prices on high-output LEDs has fallen a great deal within the last fifteen years.
LED bulbs themselves are expensive partly as it takes a number of LEDs to obtain wide-area illumination rather than a narrow beam, as well as the assembly cost enhances the overall price. Furthermore, assemblies composed of arrays of LEDs create more opportunities for product defects.
An LED light contains four essential components: an LED circuit board, a heatsink, an electrical supply, and a shell. The lights start off as bare printed circuit boards (PCB) and luminance LED elements arrive from separate factories which specialize in making those components. LED elements themselves create a bit of heat, so the PCB found in lighting is special. As opposed to the standard non-conductive sandwich of epoxy and fiberglass, the circuit board is presented on a thin sheet of aluminum which acts as a heatsink.
The aluminum PCB used in LED lighting is coated using a non-conducting material and conductive copper trace lines to create the circuit board. Solder paste will be applied in the right places and then Surface Mount Technology (SMT) machines place the tiny LED elements, driver ICs, and other components on the board at ultra high speeds.
The round shape of a regular light bulb implies that most LED printed circuit boards are circular, so for ease of handling several of the smaller circular PCBs are combined into one larger rectangular PCB that automated SMT machinery are prepared for. Consider it such as a cupcake tray moving in one machine to another along a conveyor belt, then at the conclusion the patient cupcakes are snapped clear of the tray.
Let’s check out the manufacturing steps for any typical LED light designed to replace a typical incandescent bulb with the Edison Screw. You will find that this is a very different process from the highly automated processes used to manufacture our familiar incandescent bulbs. And, despite whatever you might imagine, individuals are still very much an essential a part of manufacturing process, and not merely for testing and Quality Assurance either.
Once the larger sheets of LED circuit boards have passed through a solder reflow oven (a hot air furnace that melts the solder paste), these are split up in to the individual small circuit boards and power wires manually soldered on.
The little power source housed in the body of the light bulb experiences a comparable process, or may be delivered complete from another factory. Either way, the manufacturing steps are similar; first the PCB passes through SMT lines, this goes toward a manual dual in-line package (DIP) assembly line when a long row of factory workers add one component at the same time. DIP refers to the two parallel rows of leads projecting from your sides in the package. DIP components include all integrated chips and chip sockets.
While LED lights burn many times over incandescent or CFLs and require not even half the power, they require some form of passive heatsink keep your high-power LEDs from overheating. The LED circuit board, which is made of 1.6-2mm thick aluminum, will conduct the temperature through the dozen approximately LED elements to the metal heatsink frame and thus keep temperatures in balance. Aluminum-backed PCBs are occasionally called “metal core printed circuit boards,” despite the fact that made of a conductive material the white coating is electrically isolating. The aluminum PCB is screwed set up within the heatsink which forms the reduced half of the LED bulb.
Following this, the power connector board is fixed in position with adhesive. The little power source converts 120/240V AC mains capability to a lesser voltage (12V or 24V), it suits the cavity behind the aluminum PCB.
Shell assembly contains locking the shell in position with screws. A plastic shell covers the ability supply and connects with all the metal heatsink and LED circuit board. Ventilation holes are included to enable hot air to avoid. Wiring assembly for plug socket requires soldering wires towards the bulb socket. Then shell is attached.
Next, the completed LED light is delivered to burn-in testing and quality control. The burn-in test typically will last for 30 minutes. The completed LED light bulb will then be powered up to find out if it is working properly and burned set for 30 minutes. There is also a high-voltage leakage and breakdown test and power consumption and power factor test. Samples through the production run are tested for high-voltage leaks, power consumption, and power factor (efficiency).
The finished bulbs go through one final crimping step since the metal socket base is crimped in position, are bar-coded and identified with lot numbers. External safety labels are applied and also the bulb is inked with information, such as brand name and model number. Finally, all that’s left would be to fix on the clear plastic LED cover which is glued in place.
Following a final check to ensure all the various parts of the LED light are tight, then it is packed into individual boxes, and bulbs are shipped out.
So, in case you have wondered why LED light bulbs are really expensive today, this explanation of how they may be manufactured and how that comes even close to the manufacture of traditional bulbs should help. However, it jrlbac reveals why the fee will fall pretty dramatically on the next few years. Just as the expense of manufacturing other semiconductor-based products has fallen dramatically due to standardization, automation and other key steps along the manufacturing learning curve, exactly the same inexorable forces will drive down the costs of LED light production.