Welding Helmet Manufacturer & Supplier

Welding Helmet: The Ultimate FAQ Guide

The welding helmet is one of the most fundamental and vital components crucial to ensure the welder’s safety.

The high significance of the equipment has made it an indispensable part of any kind of manual welding operations.

This FAQ guide will lead you through all the basics regarding any information about welding helmets if you are eager to learn.

What Is A Welding Helmet?

The welding helmet is personal protective equipment (PPE) that you can wear as headgear to protect yourself from certain aspects during welding operations.

The exterior hard layer of the headgear will protect your skin from possible flash burns, ultraviolet rays produced from the welding lighting, sparks, heat, and infrared light.

Moreover, it protects your eyes from the harmful rays that might induce short to long-term damage.

In a nutshell, the welding helmet is an essential accessory during all your welding activities.

A Typical Welding Helmet

How Does A Welding Helmet Work?

Welding helmets are metallic headgear that performs as a protective unit to ensure safety for your head. The welding helmets are built with standard components and features.

Therefore, it simultaneously plays multiple safety and health roles for the welders during different welding operations.

Working With The Welding Helmet

The first and foremost function of the welding helmet is to provide yourself with a protective covering against the direct welding sparks. A very high temperature is generated during the welding process for melting and creating a bond between the melted metals.

These molten metals are often scattered like a sprinkle of incandescent droplets, which are called welding sparks. These may directly hit your head or eyes to cause severe injury.

Some of the sparks are even bigger than usual and may travel at high velocity. The thick-walled body of the helmet is designed to cover your complete head and sometimes to cover, including the neck region, to protect you from these welding sparks.

In addition, the welding helmets have a filtering screen through which you can look at the welding spot. When you perform the welding operation, a bright and high-intensity light is produced from the welding arc.

This light is comprised of severe ultraviolet radiation that is extremely harmful and may even cause visual impairment. Moreover, the brightness of the light is so high that you may suffer from temporary blinding and eye fatigue by direct contact with the source.

The filtering screen filters the rays of light into a softer form that is friendly and suitable for your eyes.

The exterior layering of the welding helmet also protects your eyes and facial skin against UV radiation, visible light, and IR radiation. Direct and long-term exposure to these rays on unprotected skin can lead to skin cancer.

If you want superior protection features for your head against all these odds, you must always use a welding helmet during all welding activities.

How Can I Install Additional Lenses In A Welding Helmet?

First of all, you have to know that all welding helmets do not support additional lenses. Only the specially designed welding helmets come with the feature where you can install additional lenses.

These helmets come with a support frame, where you need to attach the additional lens. But the support frame is different for supporting different kinds of lenses.

You need to understand the installation criteria for each kind of lenses. The requirements differ for three different lenses: cheater lenses, shaded lenses, gold welding lenses, and clear lenses. You should follow the detailed procedure step-by-step to install each kind of lenses.

Cheater lens:

Cheater lenses are lenses to help you work without prescription glasses. Compared to the built-in lenses, these lenses are not designed to survive rough environments. When the welding sparks hit these kinds of lenses, they might get severely damaged.

So, for the safety of the cheater lens, you have to install them on the interior side of the welding helmet. The main built-in lens will on the exterior side protect the internal lens from the harsh welding environment. So, follow these installation steps:

• Lift the front part towards the top to open the helmet chamber. You can see the lens mounting on the interior side.
• Locate the finger tabs or brackets on both sides of the lens mounting.
• Insert the new lens into the bracket.
• Gently push the lens. Since the lens and bracket both strictly follow dimension standards, the lens will just ‘fit in’ into the frame.
• Now, put on the welding helmet and look at the surroundings to ensure the lens is not moving.

Magnifying Cheater Lens Kit

Shaded lens:

For installing an additional shaded lens with the primary lens, you can just follow the same procedure as described above. But if you want to replace the primary lens with a new shaded lens, the process is different. For that, follow these steps:

• Locate the finger tab in the support frame.
• Using the finger tab, you have to pull the frame loose from the mask.
• Remove the previous lens.
• Place the new shaded lens on the empty support frame.
• The lens will be automatically locked, or you might have to lock it manually using the finger tab on the support frame.
• Check whether it has fit firmly or not, and the helmet is ready to use.

Gold welding lens:

The gold welding lens is special than the other lenses. In these lenses, you can see two distinct types of surfaces on two sides. One side is the reflective side, which is comparatively shinier, and the other side is mat type.

You have to install them following the same procedure as described above. But be careful to install the mat side facing towards you and the reflective side facing towards the welding spot to reflect the excessive incoming light.

Place The Shinier Side Of Gold Lens Facing Away From Yourself

Clear lens:

Sometimes you might want to install the clear lenses as a part of the shaded lens attachment. In this case, you can simply follow the procedures mentioned above.

But in most cases, there is an additional finger tab designed only for the clear lens. With this additional finger tab, you don’t need to remove the shaded lens. Instead, simply pull the previous lens from the additional bracket to slide in the new clear lens, and you are done.

Note:

Take note that all welding helmets do not come with the frame style described above. So, you can’t install additional lenses following the 100% similar procedure. There might be differences in some minor steps, but the major steps are somewhat similar.

What Is A Fixed Lens Welding Helmet, And What Are Its Advantages?

Fixed lens welding helmets:

• These are also called passive welding helmets.
• You can use a single type of shade to perform on the fixed scope of welding opportunity.
• The default shade that comes with the helmet is the #10 shade. The standard #10 shade will offer you basic protection against UV and IF rays.
• You can replace the basic shade with additional types of lenses that will suit the type of job you want to perform.
• To change the view from normal to dark feature, you have to nod your head downwards to flip down the helmet to view the weld puddle.
• For changing the view from dark to normal, you can again nod upwards to lift the helmet.

Fixed Shade Welding Helmet

Advantages of the fixed lens welding helmets:

• Since the features in a fixed lens welding helmet are very simple, it makes the units cheaper. Therefore, if you are looking for a cheaper alternative, the fixed shade welding helmets should be an ideal choice for you.
• The passive helmets are lightweight with simple components, making them comfortable with a less applied load on your neck.
• Compared to the auto-darkening helmets, the passive helmets are more optically clear through the shades.
• Additional lenses are easily available, and you can find them at low prices.
• You can work quickly for similar scopes of welding using the passive welding helmet.
• Since you do not need any additional power to run the passive helmet, you can use them at any location with convenience.
• Passive welding helmet maintenance is easy and cheaper since you don’t have to change or replace the battery. Even repairing damaged components are also cheaper.
• The lifespan of the fixed shade welding helmets is longer.
• The fixed shade welding helmets are more friendly for your eyes since they often don’t change the shade with flickering tendencies.

What Is An Auto-Darkening Welding Helmet, And What Are Its Advantages?

Auto-darkening welding helmets:

• These are also called ADF welding helmets.
• You need an additional power source to run the ADF helmets.
• The source of power may be through a rechargeable battery or solar-powered.
• The filtering screen is constituted of the liquid-crystal display, similar to a TV screen.
• The filter shade is variable.
• If the shade is not powered on, you can get a default shade of #3 or #4, through which you can clearly see.
• There are arc sensors that can detect incoming light rays. When you switch on the helmet, the sensors start working.
• With the change of incoming light, the control system computes which shade is suitable to filter the ray. The suitable shade filters the incoming ray to a version that is suitable for your natural eyes.

Auto-darkening Welding Helmet

Advantages of the auto-darkening welding helmets:

• You don’t need to nod your head every time to switch between normal and welding mode
• You can remain more focused on the welding operation.
• You don’t need to reposition the weld-gun for every start.
• With the ADF welding helmets, you can produce higher-quality welds since you can focus on the welding puddle all the time. As a result, the chances of error will reduce.
• You can work conveniently in small and tight spaces since you don’t have to lift up or flip the downwards every time to change the filter.
• The worker’s fatigue is significantly reduced since you don’t have to rely on nodding to change the shade of the welding helmet. Due to this advantage, you can work longer times much efficiently and professionally.
• Using the auto-darkening welding helmets reduces the chance of exposure to any accidental arc flash. However, with the fixed shade, the change of filter depends on manual operation. So, there is the possibility of accidental arc flash exposure if you time it badly.

But with the automatic feature, the timing is automatically controlled to keep you risk-free.

• Using the ADF welding helmet can give you a quick production line since you don’t have to change the shade between variable welding scopes.

How Does The Lens Reaction Time Affect The Welder And Welding Operation?

In the auto-darkening welding helmets, a special kind of sensor is used to detect the amount of light emitted from the welding source. When the sensor detects a very high intensive flash of light, it can determine it’s an arc flash.

As soon as the arc flash is detected, the lens is automatically darkened. This total procedure takes a small amount of time, which is known as switching speed or lens reaction time, and it affects  the welder and welding operation in many aspects:

Protecting the eyes:

Exposure to the high welding flash may cause flash burns in the eye, known as ‘arc eye.’ This is extremely harmful to your eyes and may lead to severe short to long-term visual impairment.

The lens reaction time is what switches the dark mode to protect your eyes before a sudden flash of light hits you.

Before, During, And After Shade In An Auto-darkening Welding Helmet

Ensure operator comfort:

With sufficient switching speed, the dark-mode is switched on automatically just before arc-flash can hit the eye. So, you can rely on the automatic feature and don’t have to think whether the dark feature will be activated in due time or not.

This offers you a comfort zone and helps you to focus on the task at hand with ease of mind.

Reduces fatigue and headaches:

The lens reaction time must be sufficient to activate the dark mode before the arc flash hits your eye. But it is also equally important that the switching speed is balanced to avoid very abrupt adjustment, as it might lead to an uncomfortable experience for you and lead to fatigue and headaches.

Quality and production speed of the welding:

The flickering due to imbalanced timing of switching speed will disrupt concentration, and you might lose focus on the welding operation. This will affect both the performance and production speed on the job.

The correct switching speed will help you focus on producing high-quality welds in a speedier process.

How Can I Test Different Features In An Auto-darkening Welding Helmet?

You must test different features in an auto-darkening welding helmet to ensure your safety. Here are some of the methods on how you can test different features:

Clarity check of the shade:

The shades provide darkness to filter the harmful ray of the weld flash. But it should be appropriate enough to maintain clarity so that you can focus on the welding spot.

You don’t need additional checking options to check this feature. Just strike an arc and look through the filtering shade into the arc. If you can see the weld puddle clearly with your own satisfaction, the clarity is sufficient.

Sensitivity and delay-control test:

The sensitivity and delay control settings are the most crucial features in the auto-darkening welding helmets. Locate these control settings and adjust to variable systems. Try to recognize whether the unit has properly responded to the change to ensure the headgear is working fine.

Shade filter efficiency test:

The shades must be filtering the harmful ray up to the efficient level it is intended for to ensure your safety. The best way to check for the efficiency and performance of the shade is by testing with professional apparatus.

Safety inspection:

All welding helmets must comply with certain standards and safety requirements. To ensure the certification and safety standards, you should refer to the product specifications and details of the welding helmets.

The latest standard safety protocols must conform with ANSI/ISEA Z87.1-2020, and you should look for this label with equal or latest years to complete the safety inspection.

ANSI – ISEA Z87.1-2020 Standards

Lens test:

Check for the filtering lens’s reaction time or switching speed by wearing the helmet and ensuring that the switching rate is not noticeable to your eyes with changes to light intensity.

Power source test:

For solar-powered welding helmets, take the unit outside to check whether it’s charging in daylight. You can also connect with a charger to ensure that it is being charged.

How Are The Welding Helmets Powered?

All kinds of welding helmets are not powered. The welding helmets with fixed shades do not require power to operate. The welding helmets that offer auto-darkening feature comes with the power-driven functionality.

The manufacturers of the auto-darkening welding helmets design these units with different kinds of power options, so they are suitable for various operational scopes.

Solar-powered with rechargeable, non-replaceable battery:

In this kind of welding helmet, you can find a dedicated solar panel built-in with the unit. The panel generates solar energy and converts it into electrical energy to run the variable shade system.

Generation Of Energy Using A Solar Panel

The energy produced from the solar panel is stored in the rechargeable battery. During the welding operation, the shades operate by utilizing the energy from the battery.

Since you cannot replace the battery, you have to recharge the battery by connecting to an electric source or through the solar panel.

Solar-powered with rechargeable and replaceable battery:

The basic feature of this kind of welding helmet is similar to the one described above, but there is a slight difference in terms of the battery. You can use a solar panel to charge the rechargeable battery. You can replace the other battery in case of any necessity.

Replaceable lithium battery:

Although this feature is rare, few welding helmets are designed to be powered by only lithium batteries that need to be replaced after full consumption. But you don’t need to worry much since lithium batteries can offer a long, extended battery life. So you don’t have to be concerned with frequent replacements.

Replaceable Lithium Battery

What Are Health Concerns Involved With Welding?

If you are involved in welding operations, you should be concerned about numerous negative impacts on health.

The welding materials are toxic substances that are harmful upon inhalation, and the effect of extreme UV, IF, and visible rays also cause severe health problems. The common health concerns are:

i. Arc-eye:

A very high intensive flash burn is created during the welding operation. If your naked eye is exposed directly towards the welding flash, it will damage the cornea of your eye, leading to short to long-term damage.

Moreover, if your eye is exposed to ultraviolet and infrared radiation, it may cause severe damage to your eyes.

A Patient With Arc-eye Case

ii. Acute respiratory health effects:

The acute respiratory effects develop rapidly after accidental inhalation of toxic welding fume. The common health problems concerned with acute respiratory effects are:

• Irritation of the throat track and air pathways leading to the lungs: This can occur when you inhale toxic gaseous particles or very fine dust particles to cause dryness in the throat and result in coughing and fluid accumulation in the lungs.
• Acute irritant-induced asthma: If you are exposed to higher levels of irritants during inhalation, it can cause asthma.
• Metal fume fever: If you develop flu-like symptoms resulting in fever, this might be the reason due to inhalation of weld fume generated during welding operations on mild fume.
• Acute pneumonia: Long-term inhalation of toxic welding fume may lead to lung infection and sometimes lead to pneumonia.

iii. Chronic respiratory health effects:

The chronic respiratory health effects are not caused suddenly but at a gradual pace when you are exposed to long-term welding fume. The common problems are:

• Chronic obstructive pulmonary disease: Multiple evidence suggests that COPD can develop on welders who are exposed to inhalation of toxic welding fume and dust and lead to shortness of breath, fatigue, wheezing, and other complications.
• Lung cancer: Welding fumes are classified within group 1 carcinogenic substances and may lead to lung cancer for welders exposed to welding fume.
• Asthma: Welders exposed to welding foam with metallic substituents can lead to occupational asthma.
• Welder’s lung: With exposure to long-term weld fume inhalation, fine metal particles can get deposed on the lung, leading to the welder’s lung disease.

iv. Asphyxiation:

The medical term asphyxiation can be better described with the term suffocation when the saturated oxygen levels are low in the air, and you are being deprived of sufficient oxygen. You can reach this state when performing welding operations in an enclosed room.

v. Other health effects:

The UV and IF exposure during welding operation can negatively impact the human body and cause these adverse effects:

• Effect on the skin, leading to reddening, erythema, actinic elastosis, actinic keratoses, ocular melanoma, and photosensitive diseases.
• Neurological effects like Minneapolis, leading poisoning, etc.
• Effects due to extreme noise can lead to deterioration of hearing.

UV Burns After Being Exposed To Welding Flash

What Should Be My Considerations In Choosing A Welding Helmet?

Choosing a welding helmet may sound simple. But, choosing the wrong welding helmet without adequate knowledge may lead to making wrong decisions which will affect your welders and the production line.

Here is a list of considerations you should take a look at when choosing a welding helmet:

Optical quality:

Ensuring the optical quality of the lens is critical to ensure a better viewpoint for your welder. In this regard, while choosing a fixed lens welding lens, you can ignore this option since, in fixed lens helmets, the optical quality is naturally better.

While choosing an auto-darkening welding helmet, you have to look into this feature since the shade is variable, and the optical quality may not always be of satisfactory quality. Therefore, ensure that the optical quality comes with a rating of 1/1/1.

Clear Optical Quality

Viewing area:

The viewing area is the clear part that is transparent for vision. Try to choose a larger viewing area to better focus on the weldments and the welding focus point.

Detection sensibility:

The switching time is crucial in auto-darkening welding helmets, and it depends on the sensitivity of sensor detection. For a sensor with a smaller value means that the shade can change in a much shorter time to avoid the flash hitting your eyes.

So, always try to choose the welding helmet that features very small detection sensitivity. Also, look for the lens that is rated to 1A to ensure this feature with the best standards.

Standards compliant:

You must ensure that the welding helmet you are choosing is compliant with ANSI/ISEA Z87.1-2020 or the latest standards.

Respiratory protection:

Welding helmets that come with an air filtration feature will protect you from toxic welding fume and fine dust particles during the welding operation. Choose this feature based on your requirement.

Warranty:

Ensure that the welding helmet you are choosing comes with a definitive warranty period to make sure your investment is not spoilt with faulty products.

Power function:

Depending on your necessity, you can choose the welding helmet with any type of power system between solar-powered, battery-powered, or a combination of both.

Brand:

Choosing a good brand is of utmost importance while choosing the welding helmet, as the best brands will always the best quality products. Senlisweld is your most reliable and trusted brand for choosing the welding helmet.

In Senlisweld, we always ensure the best quality of product with the highest quality for our clients, as we don’t only focus on a one-time deal, but a perfect and permanent relationship with our clients.

What Are Welding Lens Shade Number?

When you choose the lens for your fixed shade welding helmets, you can see a label with ‘Shade level,’ followed by a number. The numbers express how much the shade can filter light to refract to the other side.

If you want to understand the function of the number in simple terms, you can say that the shade with higher numbers will filter higher brightness’ light to provide more darkness.

The opposite goes for shades with lower numbers, which will filter less light to provide less darkness.

The function of the variability in filtering levels is to suit the different types of welding. As different amperage of flash is produced for the difference in the type of welding you are performing, so different levels of filtering shades are required to balance the shade with different flash intensities.

You cannot choose very dark shades for welding since they will provide you with an inadequate view over the welding spot. Again, you cannot use very light shades, as they will filter less light, which might damage your eyes.

But one thing many beginners get confused about is whether or not the shade with a lower number can filter the harmful rays of light. In this regard, you can remain worry-free.

All kinds of good welding shades, regardless of numbering, filters all harmful ultraviolet rays, infrared rays, and harmful electromagnetic radiation. The only difference in the performance involving shade numbers is in terms of the darkness filter.

Which Shade Number Should I Choose For My Welding?

The shade numbers are available within five to thirteen. Different helmets offer different shade ranges. In few helmets, you can get shade ranging from nine to thirteen, while you will get from five to thirteen in other types.

Depending on the variability of welding scope and adjustment efficiency, you can choose the type of helmet. Now to set the shade number, you have to match it with the amperage and the type of welding you are performing.

You can follow these standards to set the shade number easily:

• For plasma welding, the operational amperage range is from 1 Amp to 30 Amp arc current. Use shade numbers 6 to 10.
• For mild steel MIG with argon welding, the operational amperage range is from 80 Amp to 500 Amp arc current. Use shade numbers 10 to 13.
• For mild steel MIG with carbon dioxide welding, the operational amperage range is from 40 Amp to 300 Amp arc current. Use shade numbers 10 to 13.
• For aluminum MIG welding, the operational amperage range is from 80 Amp to 350 Amp arc current. Use shade numbers 10 to 13.
• For gas tungsten arc welding (GTAW) or TIG welding, the operational amperage range is from 5 Amp to 250 Amp arc current. Use shade numbers 9 to 13.
• For flux-cored arc welding (FCAW), the operational amperage range is from 125 Amp to 350 Amp arc current. Use shade numbers 10 to 13.
• For shielded metal arc welding (stick), the operational amperage range is from 20 Amp to 500 Amp arc current. Use shade numbers 9 to 13.
• For plasma cutting, the operational amperage range is from 60 Amp to 400 Amp arc current. Use shade numbers 11 to 13.

To choose the correct shade number, never go from lower to higher shade. First, take the darkest lens from the range provided in the standard. If it is too dark, switch towards a lower number with lighter shades until you can perfectly view the welding arc with adequate visibility.

Can We Use The Welding Helmet With Grinding Mode?

Yes, most of the newer models of welding helmets come with the grinding mode. The manufacturers offer this additional mode for quick switching to grinding mode suitable for grinding operations.

During the common welding operations, it is common that you have to switch to grinding operations to give a smoother finishing on the newly welded portion.

But the welding helmets offer you only basic protection during the welding operations, but not sufficient for grinding operation where you need extra, heavier production against grinding sparks.

So, traditionally, you have to change into a grinding helmet that wastes a lot of important time every time you want to switch. But, with an efficient switching option, you just have to press a button to flip down the grinding cover to offer heavier protection.

Once your grinding operation is done, you can again press the button to return to the welding mode. In most helmets, this switching feature is completed within 2-3 seconds.

What Kinds Of Ergonomic Features Do The Welding Helmet Provide?

The term ‘ergonomic’ implies progression in efficiency and comfort. The welding helmets will offer plenty of ergonomic features during the welding operations. The common ones are:

• The welding helmets are designed to fit perfectly with your head and provide you with a comfortable environment.
• Using the auto-darkening welding helmets, you can save a lot of time with automatic, quick darkening features and efficiently perform welding operations.
• The welding helmets are designed as a lightweight unit for your comfortable wearing and head movement.
• The sense of complete safety while efficiently performing welding operations enables you to work with the ease of mind and target-oriented goals.
• The versatile options to quickly switch into additional functions will help you be ready to work on any type of operation.

Comfortable Working With Welding Helmet

When Should I Use A Powered Air-purifying Respirator?

The powered air-purifying respirators (PAPR) are filtration systems that you can use as a portable device attached to stop inhaling toxic welding fumes and inhale filtered air. You should use the PAPRs for the following functions:

• If you want superior respiratory protection against all odds and ensure a healthy inhalation of air.
• When working on a new project and unfamiliar with the type of produced welding fume, whether toxic or non-toxic, it’s better to use the PAPR unit.
• Breathing is more comfortable and more accessible using a PAPR welding helmet during complex, labor-intensive welding works.
• The breathable air turns colder with purified air, offering you a comfortable breathing system compared to the hot, sweaty environment in the welding facility.

A Typical Powered Air-purifying Respirator

How Should I Avoid Fogging Up My Welding Helmet?

Fogging on the front screen is a common problem concerned with the welding helmet. The newer models come with few built-in features to solve this problem by maintaining sufficient air circulation.

In PAPR units, this problem is rarely visible since artificially sufficient air is circulated inside the unit. Since if you face the fogging problem with modern or traditional welding helmets, you can try these few practical steps:

• Shampoo – Gently wipe a cloth with diluted shampoo at the interior side of the viewscreen to prevent the accumulation of fog.
• Shaving cream – Same with shampoo, wipe the interior side of the viewscreen with diluted shaving cream.
• Toothpaste – Follow the same procedure.
• Adjust mask distance – Set standard mask distance from the face compliant with the manufacturer’s guide to avoiding fogging.
• Use ventilator – To maintain air circulation.
• Anti-fogging creams and wipes – Follow the same procedure.
• Raw potato – Cut and rub the lens to follow the same procedure.
• Anti-fogging film – Install thin adhesive film that functions as an anti-fogging layer.

What Are The Types Of Welding Helmets?

The different types of welding helmets are:

1. Passive welding helmets

Passive Welding Helmet

1. Auto-darkening welding helmets
2. Solar-powered lens helmet
3. Battery-powered helmet
4. Fixed-shade lens welding helmet
5. Variable-shade lens welding helmet

What Are Diopter Lenses In Welding Helmets?

Diopter lens is the other name for cheater lens.

This is basically a magnifying lens to magnify the workpiece when you look through the viewscreen. This helps to get a better view of the welding spot.

How Does More Number Of Sensors Help You In A Welding Helmet?

If you are using the auto-darkening welding helmets, the sensors detect the incoming light to switch the shade from light to dark. But during different welding operations, the sensor’s line-of-sight might get blocked due to accidental obstructions.

So, the manufacturers always design the welding helmets with multiple sensors to prevent a false alarm. The more sensors, the more you can avoid the possibility of a false alarm during welding operations. So, more number sensors are always helpful for you.

How Does The Powered Air-purifying Respirator Interact (PAPR) With The Other Personal Protection Equipment?

You may need to wear a set of personal protective equipment (PPE) units to protect yourself from negative effects on health during welding operations.

So, you have to use other PPE units with the PAPR welding helmet, which is troubling since they come with individual air-filtration chamber units. You can easily wear safety glasses underneath the PAPR welding helmet.

You can also use additional hearing protection underneath the helmet. Moreover, the PAPR often comes as a complete suite, which will cover the full body and save you from negative effects on the screen.

In a nutshell, using the PAPR unit will offer you the versatility of using different protection systems simultaneously, which will lead to comfortable and efficient working.