September 11, 2007
Autodarkening helmets do more than just protect welders from infrared and ultraviolet light the second the arc is struck. By allowing users to keep the helmet down over the face, the helmets help to prevent unnecessary neck strain, which can lead to long-term repetitive stress injury.
Autodarkening helmets have high-speed phototransistors that detect the light from a welding arc, and then quickly darken the helmet lens to allow the welder to view the arc safely. Autodarkening lenses use liquid crystal display (LCD) technology, similar to that found in flat-panel televisions and cell phones. The time it takes the sensors to register the light from the arc to the time the lens darkens is between 0.05 and 0.28 millisecond (depending on the helmet), which is up to 2,500 times faster than it takes to blink your eye (the average blink lasts 100 to 150 milliseconds).
Additionally, multiple sensors located around the perimeter of the lens are important to ensuring protection in certain applications, such as low-amperage gas tungsten arc welding (GTAW) and out-of-position welding in which one sensor may be obstructed.
All autodarkening helmets must meet the safety protection specifications of the American National Standards Institute (ANSI) and its international equivalents. Even when not darkened, the windows provide protection from ultraviolet and infrared light emissions, the two most dangerous elements of a welding arc and the cause of arc flash. Even if a helmet fails to darken when the arc is struck, the operator is still protected from the harmful effects of the light.
Most helmets need to be turned on to operate and will turn themselves off after a certain period of inactivity. If a welder forgets to turn the helmet on, he will be protected from harmful spectrums of light, but the experience is still uncomfortable. Because of this, some manufacturers offer an auto-on feature with their helmets, in which the helmet is in a constant on-mode and darkens no matter how long it is idle.
However, not all autodarkening helmets are appropriate for all applications.
Fixed shade lenses, which darken to shade 10 in most cases, usually react anywhere from 1/2,000 second to 1/3,600 second and are not recommended for frequent tack welds, GTAW, and other industrial applications. For applications such as GTAW or those that require frequent tack welds, a lens that adjusts between shades 9 and 13 and darkens in the range of 1/10,000 second is recommended.
A welder who uses a traditional helmet keeps the helmet in an up position until he is ready to strike an arc. He then jerks his head down in a nodding motion to bring the helmet into position. This repeated motion may lead to long-term repetitive stress injury and lowered productivity.
Ed Forbes, vice president of operations for Engineering Metals & Composites Inc. (EM&C) in West Columbia, S.C., said his company has never even allowed a traditional welding helmet into its plant. EM&C, a designer and manufacturer of aluminum components for small boats and yachts, is known for its high-volume, high-productivity GTAW fabrication skills.
"We knew that repetitive stress injuries can and do occur as a result of using traditional welding helmets, so we standardized all 105 of our welders on autodarkening helmets right from the start," Forbes said.
"Because autodarkening helmets are all we use, we've been able to reduce our workers' compensation insurance rates and had fewer trips to the emergency room from arc-flashed eyes than companies that use traditional helmets."
The weight of traditional helmets, up to 2 pounds in some cases, is also a source of neck strain. Autodarkening helmets can weigh up to 50 percent less and are increasingly designed with more ergonomic comfort in mind than previous helmet models.
Robert Lantrip, owner of Ourco Welding and Industrial Supplies, a Houston-area mobile welding distributor, occasionally performs his own fabrication work. After finishing the first of three fixtures he was welding, his autodarkening helmet was blown out of the bed of his delivery truck and he had to resort to using a traditional helmet.
"There was a lot of fitting and short 2- to 3-inch welds," Lantrip explained.
"I was able to weld 14 pieces an hour for the first job. On the second go-round, after my hood blew out the back and I had to use a regular hood, eight pieces an hour was the absolute best I could do, and that was pushing it."
Welding with these helmets can mean more time for welding. If a welder doesn't have to raise and lower his helmet when he's tack welding, he can save time going from piece to piece without moving the helmet at all.
The autodarkening helmet can reduce fatigue and frustration as well. A welder can get fatigued snapping his head to drop the hood down for each weld of the day. When using a traditional helmet, the welder positions his gun, torch, or electrode, and then nods the helmet into position before striking the arc. This can cause the gun, torch, or electrode to shift out of position, resulting in a dislocated start that requires reworking. Autodarkening helmets allow the welder to keep his head steady before striking the arc, greatly increasing the ability to achieve accurate starts.
"We're confident that our plant operates with much higher overall efficiency than it would if we were using traditional helmets," Forbes said.
Not all autodarkening helmets are created equal. They don't all look the same, either. Graphics on an autodarkening helmet can allow a welder to express his personality, much like a custom paint job on a vehicle.
An often overlooked benefit of a helmet is that it's a way to express individuality, and many welders receive the helmet's safety and productivity benefits almost as an afterthought. In this way, the graphics on autodarkening helmets actually serve to increase both safety and productivity.
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