Impact Driver or Impact Wrench – When to Choose What?


If you’ve ever been to a mechanic shop, a car assembly plant, or even a nearby construction site near where you live, there’s a good chance you’ve seen several Impact tools.

Impact tools are power tools that are used to perform a variety of operations on nuts, bolts, screws, and fasteners. They are referred to as power tools because they can supply large amounts of torque required to complete the job.

Let’s take a look at two of the most common tools used by DIYers and mechanics.

Impact Driver or Impact Wrench

An impact wrench is a power tool that is used to loosen and tighten lug nuts and bolts. An impact driver, on the other hand, is primarily used to drive screws and tighten nuts.

Impact drivers and impact wrenches are both power tools used for a variety of tasks. The primary distinction between the two is found in their designs as well as their usefulness.

Because the Impact Wrench has a square chuck drive size, it can work with hex-head fasteners such as nuts and screws. These hex head fasteners are inserted into a socket that is connected to the chuck drive.

The socket is typically available in sizes ranging from 3/4 to 1 inch, though other sizes are also available. The impact wrench is typically used for performing operations on nuts and bolts of various sizes due to the shape of the chuck drive and the torque available to it.

The impact driver, on the other hand, accepts 1/4-inch hex driver bits and is commonly referred to as a screwdriver specialist due to the shape of their driver bits. All impact drivers Chuck accepts only bits with a ¼-inch hex shank.

Impact drivers are primarily used for screw driving and nut setting. When compared to impact wrenches, they have a limited amount of torque available to them, but they pack the punch needed to get the job done.

When to use an Impact driver?

An impact driver should be used when typically working with long screws or large fasteners on wood. The driver bits of an impact driver is strong enough to penetrate through wood easily but they have a limitation when it comes to working with steel or concrete. For work of such purpose, an impact wrench would be your best bet.

When to use an impact wrench?

Have you ever tried to unfasten a lug or bolt that is wound very tightly? An impact wrench comes in handy in situations like that or when you want to want to carry out a job that requires a lot of torque.

There are different types of impact wrenches that come with different designs and power ratings make them suitable for heavy-duty jobs like working on trucks, conveyor belts, and your typical construction site jobs.

They come in a variety of sizes and power ratings so they are easily adaptable to different working conditions. For example, an impact wrench with a chuck size of 3/8 inch is suitable for various home improvement jobs and changing tires while an Impact wrench of ¾ inch to 1 inch is best suited for assembly lines and trucks.

Moreover, the shape of their chuck drive makes them the perfect work tool for loosening and tightening lug nuts and bolts, unlike the impact driver that accepts hex shank drill bits.

However, it should be noted that Companies have developed a hex adapter that can be attached to the impact wrench to fit the hex shank drill bits that screws use.

This adapter makes it possible to use the impact wrench for screws with the only downside being the torque requirements of the screws.

Typical impact wrenches of even the small sizes come with a lot of torque and so there is a possibility of damaging the screw threads if it is over-torqued in the process.

Companies like Bosch even developed a modified tool in the GED X line which features a square chuck drive and a quarter-inch hex drive inside capable of working with both types of bits without an adapter.

How does an Impact driver work?

A motor, hammer, spring and output shaft(anvil) are the main components responsible for an impact driver’s output.

Related post: Impact Driver vs Hammer Drill

An impact driver works by storing energy in a heavy rotating mass (hammer) and then releasing it all at once on the output shaft, which applies force to the screw or nut being driven.

The motor converts the current provided by the battery into mechanical energy. The spring transfers mechanical energy to the hammer, where it is stored while retaining a portion of the energy.

The hammer and output shaft are connected, and the spring pushes the hammer onto the output shaft, resulting in periodic hits.

During impact driver operation, the driver bit remains stationary and is periodically struck internally by the hammer as it engages with the output shaft.

The hammer and output shaft are fitted together, and the spring pushes the hammer onto the output shaft, causing periodic hits and a simultaneous release of energy from the hammer onto the shaft, causing the shaft to turn.

Because the hammer strikes the shaft at a much faster rate than the drill, more energy is released for turning the screw.

In summary, the motor takes the current from the battery which it converts to mechanical energy, the spring delivers the mechanical energy to the rotating hammer which hits the shaft each time the spring pushes onto it.

The turning of the shaft causes the turning motion of the driver bit which ultimately drives the screw into the wood or material being worked on.

How does an Impact Wrench work?

To properly understand how an impact wrench does its magic, let’s take a look at the components and the working mechanism.

An electric motor or compressed air can be used to power the impact wrench.

The power source in both cases supplies power to the rotor (in the case of pneumatic impact wrenches) or motor (in the case of electric impact wrenches), which converts the power supply into mechanical energy.

The mechanical energy is delivered by the rotor via a spring to the hammer and hammer cage, where it is stored.

When there is no resistance from the material to the chuck drive or anvil during operation, the Impact wrench functions as a basic drill.

When it comes into contact with resistance, the hammer slips from the engaging pin and rotates at a faster rate than the anvil’s turning speed. As it rotates, the hammer suddenly connects with the anvil and transfers the energy stored during its rotation to the anvil via an impact.

When the energy released to the anvil is depleted, the anvil encounters resistance once more, and the hammer repeats the impact cycle. This cycle occurs at such a rapid pace that the process is barely noticed.

The hammer’s forward and backward movement is made possible by the spring and hammer cage.

Impact Driver or Impact Wrench – which is easier to use?

The impact driver and impact wrench have different designs and applications, but their working principles are somewhat similar.

To make this comparison more accurate, let us put the impact wrench in a situation where it is used to drive screws, as the impact driver is primarily used to drive screws.

Impact wrenches are large tools, especially those with a large chuck size, and typically weigh more than an impact driver.

Working on wood would be easier with an impact driver because wood offers little resistance and thus does not require as much torque as would be produced by an impact wrench.

Using an impact wrench in this situation risks damaging the threads if the screw is over-torqued.

However, when working with concrete or steel, an impact wrench is preferable because it has the torque needed to drive the screw easily into the material.

Some cordless impact wrenches also have speed control, making it easier to limit the wrench’s output torque and avoid over-torquing the screw.

The choice of whether to use an impact wrench or an impact driver is influenced by a variety of factors, including the material being worked on. 

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Impact Driver or Impact Wrench – Which needs less maintenance

To keep your power tools running smoothly, it is important to perform routine maintenance on them regularly. This will also ensure that they last longer.

Your impact tool most likely came with a maintenance manual that detailed how to properly maintain the tool to ensure its longevity; following the instructions in the manual is a good place to start when looking for maintenance tips.

Another common maintenance rule of thumb is to:

  •  Turn off your power tool after each use
  •  Clean your impact tool regularly to remove debris and particles that may obstruct operation.
  • Do not over-torque your impact wrench as this can cause damage to the metallic parts involved.

In general, both the impact wrench and the impact driver must be maintained regularly to ensure smooth operation.

The impact wrench requires much more care than the impact driver because it deals with a lot more power and torque, which can damage the working parts if not used according to the manufacturer’s instructions.

Key Takeaway

The impact wrench and impact driver are both excellent tools to have in your toolbox.

They are both designed differently and perform a wide range of operations in a variety of situations.

The development of a 1/4-inch hex adapter for newer model impact wrenches, on the other hand, has made impact wrenches even more appealing than impact drivers.

An impact wrench would be your best bet because you would be able to perform both functions with one device by simply using an adapter, plus you would have the added benefit of the extra torque that comes with an impact wrench.


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Jason D. Turner

Hi there! My name is Jason, a keen enthusiast in power tools and their mechanisms and the sole mastermind behind the Noisy Tools. Working in a multi-national construction firm in Brooklyn for over a decade, I have developed a fair flair for different construction devices, gadgets, and their diverse operational aspects. By the dint of this platform, I have researched and reviewed various tools with utmost details of even the most trivial matters that will provide valuable insights for any prospective user.

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