Goggles are worn to protect the welder against hazards that are associated with welding therefore they are designed to protect eyes against shrapnel, harmful ultraviolet and infrared radiation and bright light. Welding without facial protection can result in serious injury and permanent blindness.
Most welding goggles are made up of three parts which consist of the lens, which allows the welder to see the runs being made, while protecting the eye from danger; the frame which supports the lens, and the strap which secures the frame to the welders head.
Safety frames are made of strong materials that can withstand high temperature, chemical and solvents and have high impact strength. Various frames are designed for different welding operations.
Plastics
Hard resin plastics are used the manufacture of welding goggle frames. Hard resin is a polymer of polycarbonate but its makeup is quite different form polycarbonate frames. They are cheaper than polycarbonate frames.
Nylon
Nylon based plastics (blended nylon) are also used in the manufacture of frames. Nylon was first introduced to the market in the late 1940’s. Nylon based frames have high thermal stability, high impact resistance, scratch proof and abrasion resistant, hypo – allergic and they are resistant to a wide range of chemicals.
Polycarbonate frames
Plastics have the advantage of being cheaper and easier to mould than other materials, but they also have a major drawback. Most plastics have a lower impact resistance than other materials. Polycarbonates are rock hard plastics with a very high impact resistance. They were originally developed for use space, such as an astronauts visor and the wind shield of a space shuttle. Due to a high demand for stronger and lighter frames, polycarbonate was used in frame production. Polycarbonates are light, offer a very high impact resistance, and are durable and scratch resistant.
Metals
In safety goggles used in welding it is rare to find a whole frame made up of metal, because metal is expensive and is a good conductor of heat. Metal parts are quite common on many goggles as they form hinges, buckles and other parts. Metal is malleable and corrosion resistant when electroplated with nickel, titanium or any other corrosion resistant metal.
Testing Safety Frames Used in Welding Goggles.
Frames are grouped according to high mass impact, durability and high velocity impact with the high mass impact being a test in which a one inch diameter steel projectile weighing 17.6 ounces is dropped through a tube 50 inches in height onto a safety lens mounted in a frame. The frame is certified okay if it fully retains the lens and no piece detaches from the frame. Durability of the frame is important because many frames are subject to hours of non-stop use. The durability test involves a lame test, corrosion test and other durability tests.
High Velocity Impact test on the other hand involves a quarter inch steel ball being shot at the lens and frame at a velocity of 150 Fs-2 from a distance of 10 inches. The high velocity impact test is repeated multiple times using different lenses and the projectile being fires from different angles.