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What Is An Impact Wrench?

What Is An Impact Wrench?
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So, what is an impact wrench? It is a type of socket wrench that is used to send high torque pressure with the user expending only minimal energy. The pressure is delivered by first storing the power that is generated from the spinning mass, then sending this power to an output shaft. The impact wrench can also be called an air wrench, a windy gun, impact gun, rattle or impactor, or a torque gun.

what is an impact wrench
Photo credits: toolreporter, pixabay.com

Video: What Is An Impact Wrench?

If you prefer learning by video, this article is also explained here:

The impact wrench was invented in Indiana by a man from Evansville called Robert Pott.

What powers the impact wrench?

The main source of power for the impact wrench is compressed air. It can also use hydraulic or electric power. The use of electricity to power the impact wrench started being common after electric devices without cords started gaining prominence in the 2000s.

Furthermore, the impact wrench is used widely in various industries. They are found in the assembly plant industries, construction industries, automotive machine repair, heavy machine maintenance industries, and virtually in any industry where great pressure is necessary for work.

In the assembly industry, pulse tools are usually used due to the fact that it has a tightening mechanism that has no reaction. The noise the pulse tool generates is quite lower compared to other tools that are used for the same purpose.

The pulse tool makes use of oil as the medium of translating kinetic energy into its anvil from a hammer. This results in a smooth impulse, a torque-weight ratio that is a little bit lower, and the probability of designing a mechanism that causes the tools to go off when the right torque is achieved.

Pulse tools, however, are not impact wrenches. This is because the technology and performance differ in some ways.

Most of the air tools that are commonly used are impact wrenches. They are available at most standard sizes of wrench drivers.

More so, you can find small sizes like the quarter inches drive tools that are used for assembling and disassembling smaller machines. You can also find the large sizes like the three and a half inches for huge plants and for outdoor constructions.

When the tool is working, the rotating mass will be moved by a motor. It would store the energy and then quickly connect to the anvil. By doing so, it creates a high-pressure impact.

What Is The Working Mechanism Of Impact Wrenches?

The working mechanism of impact wrenches is such that when the tool is done delivering impact, the hammer can spin again freely. Owing to this mechanism, the reaction force that is applied to the impact wrench is what moves the hammer.

This makes the handler feel little or no pressure even though the torque that has been sent into the socket is really high. This is just like the normal hammer. The operator sends very little pressure in swinging and nailing but the hammer itself sends a huge impact on whatever the hammer hits.

The hammer would first of all need the operator to add a little force before its hammer is let to spin without the anvil. This would cause the impact wrench to quit hammering and quickly drive nuts or bolts at the right pressure needed. Therefore, the tool can be used to quickly put or remove the fastener.

Source Of Power

The main source of power for most impact wrenches is compressed air. This makes the tool cheap to produce and gives it a good weight-power ratio.

Normally, vane motors are used. They are usually four or seven in number. The vane is always lubricated with oiled air. Some impact wrenches have a special place where a lubricant is added and sealed.

Impact wrenches send the hammer straight from the motor, imbibing it with fast action even when the nut/bolt needs a low torque. Some make use of a gear reduction mechanism before a hammer mechanism.

There are also electric impact wrenches that can be used at home and offices or in automotive industries. The volts come in 12, 18, or 24 volts.

In recent times, the cordless impact wrenches that use electricity have become popular. But their power and performance are bit lower than the ones that have cords or are powered using air.

Also, some impact wrenches are powered using hydraulic motors. These ones are mainly used to repair heavy equipment, large construction worksites, shops, etc.

What Are Types Of Impact Wrenches?

Here are types of impact wrenches:

1. Air-powered/Pneumatic impact wrench: This wrench supplies the highest amount of torque. It is the wrench of choice in professional settings. It doesn’t slow donw till its battery is off. It needs a huge compressor to work effectively.

2. Electric-powered impact wrench: This is the most convenient wrench but it doesn’t have the huge torque the pnuematic tool has.

3. Cordless impact wrench: They’re very popular with racers because the majority of racecar trailers are not built to take a high horsepower. Batteries supply cordless impact wrench with power.

There are many sizes and types of impact wrenches and they all depend on what the user wants them for.

What are the sizes of impact wrenches?

The sizes of impact wrenches are:

1. The quarter-inch wrench: This is available in two forms. The inline form (where the operator has to hold the wrench as one would hold a screwdriver with output on another end) and the pistol grip form (where the operator has to hold the wrench as if he is holding a gun).

2. The 3/8 inches impact is usually made to look like a gun. There is however a special form called the inline form which is also called the butterfly wrench. This has a flat and big throttle placed on a side of the impact wrench that controls the rotation direction.

3. Normal angle impact wrench.

4. Inline 38 inches impact wrench.

5. 1/2 inches units are just available in a pistol grip model.

6. Big impact wrench: This generates torque which is measured over six hundred thousand ft-lbs. It also has eyelets. This makes it easy to use when being lifted by a lift or crane since they are too heavy for one person to move.

New impact wrench designs combine the air ratchet and the impact wrench. They are called the no-reaction air ratchet. These ratchets make it easy for operators to use and permit the output of high torques and less effect on the user.

This reduces the risk of the operator’s knuckle being rammed into certain components of the ratchet when the bolt/nut is being tightened. There is also a sudden increment of torque.

How do you attach a socket onto an anvil?

Here are ways of attaching a socket or an accessory onto the anvil:

1. A pin that is usually spring-loaded snaps in the hole that matches the socket. This stops the socket from moving till another object is gotten and used to cause depression on that pin.

2. A second method is by using something called a hog ring to hold the socket via friction. Hog rings must be used when the impact wrench is a small one .

3. Another way to attach an accessory or socket to anvil is by using a female hex. This is also becoming more popular than pin retainers. They are used for small wrenches, mostly the cordless electric ones.

Pin retainers are usually used for this, but hog rings seem to be taking over.

Most operators use an air hose with short air length to power their wrenches instead of using an air that can be attached directly to the impact wrench.

The hose is quite useful in getting the wrench to enter cramped spaces and not having any part of the wrench sticking out at the back. It would also help make the user position rightly when using the tool.

It is also an advantage in the sense that the coupler does not easily wear due to the fact that friction caused by the vibration of the impact wrench is reduced.

A small length of the hose is also used to stop air from being cut off the tool’s base if the operator’s grip is loosened thus the tool spins.

Photocredits: Jean van der meulen, pixabay.com

Impact Drive Effects

When hammering, the resultant force from the impact wrench is short and this makes the torque hard to calculate and measure. What can be measured, however, is the energy it delivers which is fixed.

The torque varies with the pulse output. If output can absorb energy or is springy, the impulse is absorbed, and no torque can be applied. But if you have a springy object, energy is passed back to the anvil.

An impact wrench that can loosen a nut that has rusted on a huge bolt would have a hard time loosening a little screw on the spring.

What most manufacturers do is to write out the maximum torque that can be achieved. This is the instant torque that is gotten when a solid object is locked on the anvil.

Working torque, however, is a little bit realistic if the wrench is used to loosen a fastener that has stiffened.

Nut-bursting torque is also used to measure the amount of torque that could loosen a particular nut that has been tightened with a specific torque in a specific time.

Buy an impact wrench on Amazon

Perfectly controlling torque amount is hard. Even seasoned users encounter difficulties in ensuring the fastener isn’t over tightened or under tightened while making use of the impact wrench.

There are some specialized sockets that take good advantage of your wrench’s inability to function against spring. They are used to constrict torque on the bolt or nut.

Some wrenches that are used in production or assembly lines usually have a torque control structure that is inbuilt. The system consists of the torsion spring, then a mechanism which functions to close down the torque when set torque is passed.

For accuracy of tightening, a torque wrench is used in place of an impact wrench. The impact wrench functions merely to hold the fastener while the torque works on tightening it.

Because there are no known standards for calculating maximum torque, manufacturers tend to rate whatever they want.

Video: Impact Wrench VS Impact Driver.

This video shows the difference between an impact wrench and impact driver

How Does The Hammer Mechanism Of Impact Wrench Work?

The hammer mechanism is meant to let the hammer spin, impact the anvil, release then spin again. There are various designs that allow this. How much the hammer impacts the anvil is dependent on the design.

The first design causes the hammer to rotate and slide on the shaft while a spring holds it in a downwards position. Betwixt the shaft and hammer lies a small steel ball. If the shaft turns before the hammer with adequate torque, the spring compresses and the hammer slides the ball.

Below the hammer are teeth. As an operator is using the tool, the hammer turns till the teeth meet the anvil. This prevents the hammer from turning. The shaft turns still and makes the ramp lift steel ball. Consequently, the hammer is lifted until teeth cannot touch the anvil.

When the hammer can turn again, it springs towards the base of the ball ramp moved by shaft till teeth touch the anvil again. This process is repetitive. This explains why it is called the gear reduction. It makes up for its little speed by delivering high torque.

The next design makes use of a hammer that is fixed onto the shaft. They use pins as clutches. If the hammer turns beyond an anvil, a ramp sends out the pins against springs. They hit on the anvil then return to the hammer.

One downside of this model is that the pins suffer a high impact, and this usually leads to the spoilage of the wrench easily. The last model uses weight in a hammer. A long extension on the wrench’s anvil’s shaft. If the hammer turns, weight hits the anvil.

This model is great in the sense that hammering occurs just once in every revolution. the design is the simplest. But its disadvantage is that the weight causes the wrench to vibrate a lot.

In 2016, new models were made. In these new models, the hammering occurred in a hydraulic liquid so that noise and vibration would reduce as metal-metal contact reduced too.

What Are The Accessories And Sockets Of Impact Wrenches Made Of?

The accessories and sockets for wrenches are usually made of metal with high tensile strength. This is because the spring would lesson torque in a fastener. The continuous impacts need a metal that is strong enough, so the tool does not easily break down and spoil.

The parts of the wrench that do not face impacts are usually made of brittle metal. They are harder than the metal used to make the side that faces impacts.

Safety glasses are a must-wear when you are working with the tools. This is to prevent injury. While working with wrenches, quick and powerful impacts can send shrapnel coming your way. And if care is not taken, they would fly in and hurt your eyes.

What Are The Uses Of Impact Wrenches?

Here are the uses of impact wrenches:

1. They are used to change lug nuts when fixing or removing a tire.

2. They are used in the automobile industry to assemble car parts.

3. They are used to assemble heavy instruments and tools.

4. They are used in the manufacture and maintenance of machine tools.

5. They are used in large construction duties.

6. They can be used to secure nuts and bolts on beds, cupboards, and wardrobes.

7. They are used to affix bolts and nuts used to support huge pillars and bars.

8. In automotive shops, they can be used in garages to loosen tight and rusted nuts.

What Are The Differences Between Impact Drivers And Impact Wrenches?

Here are the differences between impact wrench and impact drivers:

1. Impact wrenches are harder to use, heavier, bulkier and more powerful than drivers.

2. Impact wrenches are used for bigger and harder duties while impact drivers can be used for smaller duties in the home.

3. Impact wrenches are used to loosen or tighten nuts and bolts whereas impact drivers are used to drill long screws into wood or metal.

4. Impact wrenches are used more for car reparations whereas impact drivers are mostly used for renovations and DIY.

5. Impact wrenches have a ½” square drive whereas impact drivers have a ¼” hex collet.

Can You Use An Impact Wrench As A Drill?

You can use the impact wrench as a drill. This is dependent on where it is being used. For home equipment that may not need full force, it is advisable to use an impact driver instead.

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