Through a Glass, Darkly
Auto-darkening hoods' evolution yields greater precision and welding vision.
THE technology available in today's auto-darkening welding helmets was the stuff of science fiction to welders 30 years ago. A single lens capable of darkening automatically to a variable, preset shade level the instant an arc is struck would have sounded about as realistic as a "Star Trek"-style "transporter" or a cell phone that can take pictures.
"It would have been complete and total science fiction," said Kevin Coughlin, president of Hoodlum Welding Gear, Minneapolis. "The technology really didn't exist, so it would be like me telling you your car will be flying in 20 years--you'd look at me and laugh. Even 25 years ago, if someone had told me [the lens] would go from clear to dark when you spark, I'd have said, 'Yeah, right, sure it does.'"
Skepticism persists among many in the welding community, the majority of which still relies on standard fixed-shade lenses to do its work. Harvey Cross, who learned to weld in 1962 while serving aboard the U.S.S. Lexington using what is now referred to as a "traditional" or "conventional" flip-down hood, said that even with today's auto-darkening hoods' typical switching speed of 1/20,000 of a second, his mind would have been on physics' golden rule that nothing can be transmitted faster than the speed of light, making it hard for him to trust that he would not get flashed. "I'd have hated to be the first one a salesman handed such a helmet to try out," he said. "I might have tried it, but I would have done it with my eyes closed."
Such basic distrust of the technology's performance capabilities is understandable, given some of the problems early helmet models had to overcome. In 1976, Speedglas founder Åke Hörnell combined liquid crystal cells, polarizing filters, and electronics to develop the prototype for an auto-darkening filter, but it wasn't until the early 1980s that companies began making the technology commercially available. At the time, problems were reported of the helmets' erratic behavior caused by the on/off arc in the TIG welding pulse mode, for example, or of the helmets being "fooled" by bright outside light.
"When they first came out, they were just racked with problems in their electronics, performance, and reliability," Coughlin said, "but now all those things have for the most part been solved." As the technology surrounding the helmets' sensors, power cells, lenses, and other electronic components has evolved and improved, so, too, said Coughlin and other helmet manufacturers, has welders' perception of the equipment and their eagerness to use it.
Eyes Wide Open
The central ability of the auto-darkening lens to darken and lighten automatically with the welding arc's respective firing and extinguishing is the wellspring of a number of safety and ergonomic benefits that are literally eye opening. According to Jim Harris, product manager at The Lincoln Electric Co., Cleveland, "A lot of people are under the misconception that it's the darkening of the helmet that protects your eyes. Actually, that's purely a comfort issue." Harris explained that damage and discomfort to welders' eyes result primarily from the welding arc's emission of ultraviolet and infrared radiation, both of which are prevented at all times by all helmets that comply with the current ANSI Z87.1 standard--even when the helmet is turned off.
Cliff Frey, St. Paul, Minn.-based 3M's senior technical services representative, elaborated on this protective quality of the helmet, noting that the hoods provide the continuous protection from welding radiation via a permanent, built-in, non-electronic band-pass filter. If, in a worst-case scenario, a helmet's electronics were to fail and not trigger the liquid crystals that normally provide the appropriate split-second shading, the visible light allowed in the hood might be as dazzling as a camera's flashbulb, he said, but would not be capable of causing "arc eye," retinal burns, or other damage because the wearer's eyes would still be completely filtered from the harmful rays. "As long as you have your faceshield down, regardless of whether there are even batteries in the system, you'll get the bright light but you will not get burned," he said.
Enabling welders to keep their faceshields down at all times in the welding process is the critical safety feature of auto-darkening hoods. Whether they're doing tack-up work, hitting a corner, starting a new bead, or inspecting their weld, most welders are constantly stopping and starting. And every time they do, if they're using a traditional helmet, they're raising its faceshield in order to see, leaving their eyes and faces vulnerable to flying metal particles, neighboring arcs, and any number of potential hazards.
"Any time you can keep the lens down it's safer, and that's what these [auto-darkening] helmets allow you to do," said Jason Suarez of Palatine, Ill.-based Sellstrom Mfg. Co. "Because you can still see through the lens when you stop welding, you don't have to lift the lens, and your hands remain free. If you're welding in, say, a tight space, you don't have to get out of it just to be able to lift the hood in order to see again."
The Flip Flak
The continual raising and lowering of the faceshield necessary with the traditional, passive helmet is not only inefficient and potentially hazardous, it's a highly repetitive motion that should keep any self-respecting ergonomist awake at night. Although OSHA recommends always using the hands to do the raising and lowering, the reality is that, because they lack a third hand for the job, welders routinely resort to lowering the shield with a musculoskeletal-jarring snap of the neck.
Tulsa Welding School Director of Training Jamie Pearson said, "The truth is, if you used your hand to pull down your hood before you struck an arc, half the time you'd be striking your arc where you didn't need to strike it. When you've got a filler wire in one hand and your TIG rig in the other and you're positioned where you need to be positioned, you're not going to move your hands to reach up there and flip down your hood. It's not reliable, so generally you're going to flip it down with your neck. . . . And after doing it for seven or eight hours solid, you don't have a neck at the end of the day."
Tom Sommers, product manager for Miller Electric Mfg. Co., Appleton, Wis., said no matter which method they choose for lowering the lens, users of traditional hoods always have to deal with a momentary period of blindness that could affect their precision. "With the conventional helmet, when you go through that flipping motion, you're in the dark until you strike the arc," he said. "With auto-darkening helmets, because you can see your weld and where you're positioned right up until the moment you strike the arc, you can potentially get a better-quality weld. Productivity increases, too, because you're not having to stop, raise your helmet, reposition, and lower your helmet. With the auto-darkening, you can move from one spot to the next, unimpeded."
Maintaining visibility throughout the welding process, from arc to finish, is a crucial part of many applications and one of auto-darkening's major advantages. Pearson said he has seen people lose jobs while performing pressurized pipe and other code work, for example, after inadvertently moving their filament or even slightly changing their form during the momentary blindness of the neck flip, resulting in their failure to strike their arcs within the weld zone as code requires. Frey added that in repair welding and high-precision industries such as aircraft manufacturing, where welding turbine blades and other sensitive components takes place, the visibility and precision auto-darkening hoods afford can be critical.
Minding the Gap
Some of the latest variable-shade helmets are equipped with literally dozens of user-selectable combinations of shade, delay, and sensitivity settings and are designed to accommodate the full gamut of welding applications, from grinding and cutting to plasma and carbon arc welding. Some brands feature user controls on the outside of the helmet, allowing welders to change their settings while welding without even removing their gloves.
Of course, such options come at a price. "The more bells and whistles you have, the more different types of welding processes you do, the more expensive you get," said Steve Kickham, director of marketing for St. Charles, Mo.-based Jackson Products Inc.
Historically, the cost difference between auto-darkening and traditional hoods has been considerable, but that gap has narrowed in recent years. As the technology continues to improve and prices continue to drop, some manufacturers feel the industry is at a crossroads and that it's just a matter of time before auto-darkening hoods become the standard. Coughlin noted, for example, "The price of a helmet with an electronic lens dropped from $200 to $59.95 in the span of 24 months. That brings a whole lot of consumers into the electronic age."
Others are cautiously optimistic about auto-darkening's market ascendancy. Higher-end hoods are still in the $300 range and, as Harris noted, "Unfortunately, there is a lot of product that's not really apples to apples out there." Many large companies are still ordering passive helmets precisely because of the significant price difference, but the demand for auto-darkening hoods is nevertheless gaining ground, Suarez said. He added that because increasingly more welding schools are ordering auto-darkening hoods, he sees the trend continuing in auto-darkening's favor, assuming people will want to use the equipment on which they are trained.
Ed Martin, president of Taunton, Mass.-based ArcOne, said from the standpoints of safety, comfort, and user friendliness, the trend is clear: "The bottom line is, if you're a young welder today, you've got to have your head examined not to start off with an auto-darkening filter."
Back to the Future
"In another 20 years, I don't think we'll realistically have any kind of old-style hoods around," Pearson speculated. Martin had a different take, saying, "Twenty years from now is long enough for auto-darkening filters to be phased out as well, in favor of a new technology. The process of welding will continue to change and so will welding protection. Suffice to say, the 'art' will continue to evolve as the passive, old-style will continue to fade away."
This article appears in the October 2005 issue of Occupational Health & Safety.
This article originally appeared in the October 2005 issue of Occupational Health & Safety.