Impact Driver vs Impact Wrench: What’s the difference?

No two power tools are exactly alike.

While many people use the names impact driver and impact wrench interchangeably, they are in fact very different tools, designed for different tasks.

So, what exactly is the difference between an impact driver and an impact wrench?

Impact Driver vs Impact Wrench: Quick Answer

An impact driver and an impact wrench are not the same tools. Both are designed to generate high torque output, but they are suited to different applications.

An impact driver is best for small to medium fastening jobs, such as screws.

An impact wrench is best for heavy-duty loosening and tightening. It has high speed with low torque, which makes it perfect for removing lug nuts from a tire or tightening large bolts like those on engine manifolds or suspension assemblies.

An impact driver uses a chuck to hold screwdriver bits, and it delivers rotational blows as well as linear to drive or loosen fasteners.

An impact wrench uses sockets, which attach via a spring-loaded pin lock or a retaining ring, and it provides high torque output for loosening large fasteners, such as lug nuts.

What’s an Impact Driver?

Milwaukee Impact Driver

An impact driver is a power tool that’s better than a drill for driving in screws.

The bit’s hexagonal shape lets you use either a Phillips, square, or Torx wrench on it.

An impact driver looks more like a drill than a screwdriver, and it has an additional feature that makes it ideal for driving screws: The hammering action creates a high rotational torque.

In fact, the tool is so strong that it can drive long or large screws into hardwoods even with its factory-set clutch setting (most impact drivers ship set near their maximum torque output).

How does it work?

An impact driver uses both bit rotation and concussive blows to power through tough jobs. This makes them more powerful than a drill/driver.

As an impact driver turns, it puts pressure on the tip of the bit. This pressure causes the bit to dig into the screw head and prevents it from slipping out of place, even if your hand slips off the handle. The impact driver’s torque also helps you drive screws into lumber faster than a drill can manage.

While they aren’t intended for this purpose, an impact driver can also drill holes if you have bits with a compatible shank.

Types of Impact Drivers

There are two types of impact drivers: cordless and corded. A cordless model gives you the freedom to move around your work area without having to unplug from the wall.

The downside is that they need to be recharged or have their batteries replaced when they run out of juice. Corded models don’t have this problem, but you’re limited by the length of the extension cord you’re using.

Benefits of Impact Drivers

The upside is that they’re easier to use than drills: they’re lighter and more compact.

They don’t need any clutch settings, and since they drive screws by hitting them very hard instead of spinning them fast

Their batteries last longer and you don’t have to worry about stripping the heads of soft screws like drywall ones.

Downsides of Impact Drivers

The downside to impact drivers is that they’re not as good as drills at drilling holes without spinning the screw head, or at driving in long lag screws while keeping the head flush with the surface.

They’re also not as good at making adjustments (e.g., hanging a curtain rod) when you need to tighten or loosen a screw just a little bit.

RELATED: Brushless vs Brushed Tools

What’s an Impact Wrench?

Milwaukee Impact Wrench

Impact wrenches are used for loosening and tightening nuts and bolts. They are power tools that store energy in a rotating mass, then deliver the energy to the output shaft.

Their main advantage over other power tools such as electric drills is that they deliver a strong, sudden rotational force (impulse) rather than a constant rotational force.

This makes them ideal for applying large amounts of torque to tighten or loosen stubborn nuts and bolts without stripping or damaging their threads, especially when working with rusty bolts and nuts.

Impact wrenches store energy by repeatedly engaging and disengaging a clutch, using flyweights attached to an output shaft. The impact part of the name comes from the sudden engagement of the clutch; this sudden engagement gives the tool its characteristic “thunk.”

The most familiar type of impact wrench is the air impact wrench, or “air gun”, driven by compressed air from an external compressor.

Impact wrenches can also be driven by pneumatic, hydraulic, or electric motors.

How does it work?

An air impact wrench has three main sections: an air motor; a hammer and anvil mechanism.

It also has a transmission that converts the rotary motion of the motor to a reciprocating motion of the output shaft, so that it hits the anvil each time it turns around.

The hammer and anvil are contained in a cylindrical housing, which is attached to the transmission’s input shaft. Inside is a spring-loaded pin that sticks out from the side of the cylinder, then curves back on itself to form a C shape.

This pin makes contact with two other pins attached to the anvil and hammer. A spring keeps them all together when the wrench is not under load.

When you press down on the output shaft, this forces air into the front of the motor, spinning its rotor.

The rotor has holes in it which allow air to escape through its rear end while it’s spinning (this is known as exhaust porting).

Types of Impact Wrenches

There are two types of impact wrenches: those with a hammer-and-anvil mechanism and those with the hammer clutch design.

The hammer-and-anvil mechanism has two plates that strike each other, creating short bursts of rotational force through an anvil.

The hammer clutch design has a spinning mass that moves freely around its axis of rotation, striking multiple hammers mounted around its periphery as it spins.

These hammers strike a ring gear attached to the output shaft.

Benefits of Impact Wrenches

Impact wrenches are extremely convenient to use. In most cases they require little or no advance set-up and can be used immediately with no skill required.

They’re lightweight, making them easy to handle compared to other power tools. Their shape is also very ergonomic and quite convenient for both professional mechanics and do-it-yourselfers alike.

They are powerful enough for most practical purposes. They deliver high torque, allowing the user to easily fasten or unfasten the largest nuts or bolts with ease.

For heavy-duty applications, they’re a great choice because they produce significant torque while still allowing you to control how much force you apply.

Downsides of Impact Wrenches

Impact wrenches are not well-suited to all applications.

They can cause damage to fasteners that aren’t strong enough, so they should never be used to tighten small bolts or screws.

Takeaway

An impact driver and an impact wrench are not the same tools. A driver is best for small to medium fastening jobs and the wrench is best for heavy-duty loosening and tightening.