Evaluating auto-darkening welding helmets
June 29, 2018
Guy Shelverton, Global Product Manager, Equipment Accessories & PPE, ESAB
While radical graphics may have surface appeal, they're no guarantee that an auto-darkening welding helmet offers adequate performance. What, then, are the technical factors that constitute a premium top tier helmet? As a starting point, consider these features and functions when evaluating a helmet: comfort and balance; auto-darkening filter (ADF) technology and size, shades and modes, controls, sensors, batteries and shell design.
Comfort and Balance
According to ESAB's voice of customer research, welding operators value comfort and balance more than any other attribute. Headgear is as important to a welding helmet as a tyre is to a race car: the point of contact is what makes the difference. A typical welding helmet provides three points of contact. A headband provides primary contact points on the forehead and the back of the head, with a ratchet mechanism to adjust band diameter. Padding for the forehead and the back of the head may or may not be provided. To keep the helmet from slipping down, a band goes over the top of the head. Combining all possible options for adjustability, a typical helmet has about 100,000 possible combinations.
Next generation helmets have headgear that provides five points, such as the Halo™ headgear on the new ESAB Sentinel™ A50 helmet. Distributing the weight over more contact points reduces the perceived weight on the helmet. It also provides greater adjustability - more than 500,000 possible combinations in total. Think of headgear adjustments like the gears on a mountain bike: the more options you have, the more comfortable the ride. Operators with smaller or larger than average heads will appreciate this flexibility.
To further reduce perceived weight distribution, look for helmets with a lower pivot point. When the helmet is in the up position, not only is a lower position more comfortable, it also reduces the chance of the operator catching the helmet on obstructions when working in tight areas (realistically, it's only a matter of when, not if, the operator will knock the helmet off his head).
Perceived weight distribution is directly related to the size of auto-darkening filter (ADF), which comprises the majority of a helmet's. A larger viewing area requires more glass and weighs more (and incidentally costs more; the ADF typically accounts for 60 to 70% of helmet cost). While oversize viewing areas have been popular, many operators say that a viewing area of approximately 4 x 2.5 inches is ideal for seeing the joint while helping reduce weight and keeping the helmet more affordable.
Ten years ago, switching speed of the lens (which is actually an LCD screen) was an issue on low-end helmets. Today, many of the top-end lenses switch from a light to dark state at speeds of 1/25,000 of a second. To put this in perspective, the human eye takes 3/10th to 4/10th of a second to blink. Further, the lens has a permanent passive filter to protect against UV and IR light. Even if the ADF fails to darken, the UV and IR filter helps protect the eye.
As ADF technology has advanced, there's more differentiation between low- and high-end helmets. Operators now need to learn how to evaluate optical clarity. The European Norm (EN) 379 Standard is a standard recognised worldwide to provide welders with a rating system by which they can evaluate ADFs. The standard sets performance requirements for optical quality and evaluates them on a scale of 1 to 3, with class 1 being the highest. The four factors that determine quality are:
- Optical quality 1, 2 or 3 - indicates optical quality of the ocular.
- Light diffusion class (switchable filters only) - indicates light diffusion by the ocular.
- Variation in luminous transmittance (switchable filters only) - indicates shade variability in the dark state of the ocular.
- Angle of dependence of luminous transmittance (optional) - if applicable, marked before the standard number.
EN 379 Standard states that the highest optical classification is 1/1/1/1. The Sentinel A50, with a 1/1/1/2 optical class rating, offers a sharp, clear and consistent view of the weld puddle without the extra cost to obtain the angle dependency 1 rating, a difference that most operators find difficult to perceive. What operators can easily perceive, however, is the color tint of the lens.
Until 2008, most ADFs created a greenish cast that muddled the varying shades of red in the weld puddle and the heat-affected zone (HAZ). Newer ADFs offer more of a true colour perception, transmitting a blue tint from the weld and actually emitting more light than from a green tint transmission. Recognising true colour helps operators better read the weld puddle and the HAZ, critical factors for puddle control and bead placement.
To further help operators, the Sentinel helmet offers front lens covers in clear and amber. Just like tinted shooting glasses provide marksmen with greater contrast between the target and its background, an amber tint can improve contrast between the weld puddle and the rest of the joint, as well as enhance the light in low-light conditions.
Of course, ADF shade affects view the most. Not too long ago, premium helmets offered a shade range of 9 to 13. Newer top-tier helmets offer range of 5 to 13. The lower ranges help when TIG welding at low amperage (more on this shortly), when using small diameter electrodes at lower amperages and when plasma or oxy-fuel cutting (cutting goggles and glasses often come in shade 5). To prevent operators from accidentally using a low shade number in a high amperage applications, some helmets require the operator to manually toggle between low (5 to 9) and high (9 to 13) ranges.
In addition to shade ranges for welding and cutting, top-tier helmets also offer a "grind mode" of shade 3.5 or, most commonly, shade 4. Activating the grind mode, such as by pressing a button on the outside of the helmet, fixes the shade of lens so that operators can grind without the grinding sparks causing the lens to darken to a welding state. Welding helmets with modes for welding, cutting and grinding replace the clutter of different PPE for these tasks and eliminate downtime when switching between applications.
About TIG welding at extremely low amperages: welding at 2 to 5 amps AC or DC can cause some ADFs to flicker in and out of the darkened state. Some top-tier helmets are rated for low-amp TIG welding, and others are not. Before choosing a helmet for low-amp TIG, be sure to read the fine print in its technical specifications.
Other helmet control functions include "sensitivity," which adjusts how much light it takes the ADF darken. This function particularly helps when welding outdoors, where sunlight can cause the ADF to darken before the operator strikes and arc. The "delay control" function enables the operator adjust how long it takes the lens to react after the operator breaks arc, such as from 0.1 to 1.0 second in 0.1 increments. This function helps in high-amperage applications (notably Flux-Cored welding with large diameter wires), as it keeps the lens dark a fraction of a second longer to give the weld puddle a chance to cool and lose some of its "cherry red" intensity.
Some ADFs also provide memory functions to store pre-selected settings for shade, sensitivity and delay. For operators who frequently switch between applications (such as from low-amp TIG to high-amp TIG to Stick to MIG to Flux-Cored), the memory function eliminates fiddling around with settings before welding (and, being honest, lets operators weld with the optimum settings instead of just making do with a less-than-acceptable setting).
As for the controls themselves, most helmets have mechanical switches and knobs located inside or outside the helmet. One shortcoming is that settings can be hard to read in low-light conditions. To address this issue, some helmets are using colour touchscreen LED technology similar to that of a smart phone, which clearly displays numbers in any light.
Sensors and batteries
Typically, ADFs have either two or four sensors located in the corners of the cartridge. Professional welders prefer helmets with four sensors, especially if they weld out of position, because having more sensors reduces the likelihood of blocked sensors. Some top-tier helmets (the ESAB Aristo® Tech HD being one) also use electromagnetic arc sensors that automatically react to the magnetic field of the arc. This eliminates interference from sunlight or other electrical/electronic equipment, as well as ensures that the helmet darkens when the sensors are blocked.
To change from a light to dark state, ADFs use a variety of technologies, including solar power, lithium batteries (typically CR2450) or a combination of lithium batteries and solar power. There is a widespread misconception that the solar power recharges the batteries; that's not true. Rather, after the battery provides the power for the ADF to darken, then solar power provides a supplemental power stream to the keep the ADF darkened. This allows the helmet's control circuitry to rely predominantly on solar power, minimise the battery drain and extend battery life.
Shells and cover lenses
Regardless of price, all welding helmets must meet the ANSI Z87.1 (and/or CAN/CSA Z94.3) standard, which covers impact resistance, flame resistance and light leakage. That said, some helmets will be more durable than others depending on construction. Those that use a nylon-reinforced polymer will provide exceptional durability.
Welding helmets use a plastic lens protect the ADF's glass from spatter, smoke, scratches and impact. Some lens cover designs permit change in a matter of seconds, while others require removing the entire ADF, which can be time-consuming and annoying. If an operator will be welding in situations that create a lot of spatter and smoke, this is significant consideration.
Following the suggestions above will help guide users to an informed decision. Speaking from a corporate perspective, note that choosing a good helmet doesn't just improve operator productivity and comfort, it goes a long way toward enhancing operator satisfaction - and happy operators are always more productive. Of course, there's no substitute for getting under the hood and seeing what the weld puddle looks like through the ADF. Trade shows, distributor open houses and events where welding suppliers will be present (especially car and farm shows and races) all provide a good opportunity to find the best fit for your head.