Welding is a significant work in many industries i.e. automotive, construction and aviation industries. The primary purpose of welding is to bind different metal surfaces. One most important question comes to many minds: how does an auto-darkening welding helmet work? While welding, different radiations are emitted, like Ultraviolet rays, Infrared radiation and intense visible radiation.

These radiations can cause severe damage to the skin and body if a welder is not fulfilling the preventive measures. Infrared radiation can even burn the body as these radiations are high-energy radiation. There are different kinds of welding helmets available in the market. But welder loves to use quality auto-darkening welding helmets due to their features. Safety should be your priority while doing any job.

There are many benefits of using an auto-darkening welding helmet over a simple welding helmet. There are sensors near the glass that detect radiations emitting from the arc and adjust the lens accordingly. To understand it completely, one must go through its components and the working system.

Know How an Auto-Darkening Welding Helmet Works

With the working of a welding helmet, it is also vital for a welder to know how to test an auto-darkening welding helmet. There is a little red spot on the infrared radiation sensor on the helmet’s screen that makes the screen black when it detects the radiation. The number of sensors varies with the model. In the old and cheap models, you will find only two sensors; on the other hand, there are four sensors in modern and premium models.

A special sensor (X-mode) is available in the latest models to detect electromagnetic fields. This X-mode sensor detects the electromagnetic field generated through welding. In response to the detection of the electromagnetic field, the view turns dark for the operator. Now, you probably get the answer to your question how does an auto-darkening welding helmet works.

What’s Inside an Auto-Darkening Helmet?

There are several layers in an auto-darkening helmet. These layers act as a filter for the radiation coming out from the arc to the welder. A welder should also know the difference between auto-darkening and passive welding helmets. It will help you to make the right decision when choosing a welding helmet.

Understanding these major components will help you to understand how does an auto-darkening welding helmet works.

  • Infrared/Ultraviolet radiation filters
  • Polarization Filter
  • Liquid Crystal Cell
  • Light sensor and Arc sensor

Structure and Working of IR/UV Radiation Filters 

These filters give violet color to the lens and filter out 99.99% of infrared and ultraviolet radiation. A reflective thin glass layer also filters out remaining ultraviolet and infrared radiation. This thin glass layer consists of 11 metallic layers these six layers are of Aluminum Oxide (Al2O3) and five layers of Silver ( Ag). The structure and working are vital to knowing how does an auto-darkening welding helmet works.

The penetration power of ultraviolet radiation is more than infrared radiation. So, to remove its effect, polarization lenses work along with the glass layer. But in recent days, the number of layers has reached up to 20. The thickness of these metallic layers is 5 microns. So, the filter capacity is increased. The only problem with these filters is that when a welder starts welding, he faces difficulty in seeing the object for a moment.

Structure and Working of Polarization Filters

There are a total of three polarization filters in an auto-darkening welding helmet so, vital to understand how does an auto-darkening welding helmet works. After every layer, there is a polarization filter in the self-darkening helmet. This polarization filter aims to remove the bright light that is coming out from the arc of welding.

These filters help to see the clear view of working with an auto-darkening helmet. After the UVR/IRR filter, the polarization filter is oriented at 90 degrees and in this state, it becomes darkest. So, you get a clear idea of how an auto-darkening welding helmet works.

Structure and Function of Liquid Crystal Cells

This liquid crystal cell aims to reduce the amplitude of incoming light after the UVR/IRR filter and polarizing filters. In simple words, to reduce the energy of incoming radiation. Two liquid crystal cells are present, which are sandwiched between three polarization filters. This filter works efficiently when incoming light is polarized.

You can adjust the liquid crystal cell in any direction according to the requirement of bending the light incoming from the screen of the self-darkening helmet.

Light Sensors and Arc Sensors

Several light sensors and arc sensors are present in the helmets. The purpose of the light sensors and Arc sensors is to detect the intensity of light and adjust the lens according to the intensity of light. Arc sensors deal with intensely bright light, while the Light sensors filter out extra light in the standard welding procedure.

Read More: Minion Welding Hoods their Features and Benefits


How does an auto-darkening welding helmet change its shade?

When light or arc sensors detect the arc, they send a signal to the Liquid Crystal Cell. When liquid crystal cells detect the signal, they turn themselves according to it. In normal conditions, they are flat while they can turn up to 90 degrees.

What is the reaction time of auto-darkening welding helmets?

The reaction time of a welding helmet is vital because it is in response to the arc and is in 1000s of a second. It varies with the quality of a helmet. The average response time of auto-darkening welding helmets is 1/25,000 seconds. While new technology welding helmets express an even greater response which is 1/20,000 of a second.

Are auto-darkening welding helmets safe for the operator?

Of course yes, Auto-darkening welding helmets filter out the hazardous ultraviolet, infrared and intense visible light. The lens used in helmets only allows the light to pass through that is not harmful to the eyes of a welder.

Is there any battery in auto-darkening welding helmets?

Yes, there are batteries present in auto-darkening welding helmets. Most of the time these batteries are solar-powered. These are necessary for the initial switching of the welding helmet. Once the procedure is initiated, the solar cell powers the liquid crystal filters and lithium battery present in it. Some people think that there is no battery in the cheap solar welding helmet while the battery is present that is not replaceable.

How to use solar-powered auto-darkening welding helmets?

Solar power auto-darkening welding helmet differs from others because you must check whether it is charged or not before welding.  It is recommended to put it in front of sunlight for a day so the battery is recharged for proper functioning.

What type of batteries do auto-darkening welding helmets use?

Mostly the replaceable batteries used in auto-darkening welding helmets are CR2450 and CR2032. Both batteries have the same voltage while CR2450 is of larger volume therefore its capacity is more than CR2032.

How long does an auto-darkening welding helmet last?

The life of a welding helmet depends on the type of batteries used. If the battery is not replaceable then it will only last for 5 to 8 years. In the case of replaceable batteries, helmets can do the job for a very long time.

Do auto-darkening welding helmets go well?

It depends upon the type and condition of the welding helmet. After a few years, more hours of charging are required in the case of solar-powered auto-darkening welding helmets. So before buying, you must know how does an auto-darkening welding helmet works. It will help you to make the right decision. 

How to select an auto-darkening welding helmet?

You should check the quality, weight, number of shades and reaction time before choosing an auto-darkening welding helmet. Also, make sure it is safe and meets all standards. You can also do a Sun test to check its quality. In this test look towards the Sun while wearing the helmet and check how dark and fast your lens is.

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