How Does An Impact Driver Work?

Impact drivers are very popular power tools among contractors, professional carpenters, and DIYers alike because of their power, versatility, and easy operation. They provide the high torque necessary to drive long screws into wood or metal and loosen over-torqued and corroded screws, nuts, and bolts that are jammed.

You probably already know that an impact driver uses a combination of rotational force and quick bursts of impact when facing resistance, but have you ever wondered what the tool looks like inside and how it works, exactly?

In this piece, we’ll be exploring the inside mechanism of impact drivers for those who are curious about how the components work together to provide such powerful torque.

How an Impact Driver Works

How an impact driver works!

If you were to open the casing of an impact driver, you’d see that it has four main components inside: a motor, a spring, a hammer, and an anvil.

The motor converts electrical energy into the mechanical energy that’s needed to rotate the chuck. As the chuck turns, the spring is compressed by the hammer. The spring is forcefully released at a certain point, driving the hammer against the anvil just like a regular drill.

But when the impact driver’s motor alone isn’t enough to provide enough torque to fasten or unfasten the screw, bolt, or nut, the spring-loaded hammering mechanism is automatically activated.

So, whenever the motor experiences resistance, the hammer is pulled away from the anvil while it continues to rotate, and then it snaps back into position. It’s this combination of continuous rotation and quick bursts of impact which allow the impact driver to provide the high torque it’s known for.

This whole process happens rapidly, and it’s repeated approximately 50 times per second, depending on the model, for as long as you press the trigger.

Why is the impact necessary?

Have you ever struck a wrench with a hammer to get it to fasten or unfasten a nut or a bolt? Well, the impact driver follows the same principle, but on a smaller scale.

Thanks to the fast continuous impact of the hammer against the anvil, you can drive longer and larger screws through hard materials such as metal and hardwood, a task that a drill would be unable to tackle.

What’s more, impact drivers are designed to work in tight spots and awkward angles where you can’t fit other tools or apply the necessary pressure to drive in or loosen the screws.

On the downside, impact drivers lack the torque control standard drills have. If you need precision as regards the placement and size of the hole, you’ll have to be extra careful with the driver in order to avoid stripping the screws and damaging the surface.

Even if you could use a drill, you risk injuring your writs due to the increased pressure you need to apply for it to work. Using an impact driver would be easier on your wrists because they’re lighter and offer no resistance at all, as they apply the downward force to the screw instead of your wrist and forearm.

If the screw is completely jammed, you also risk killing the motor of your drill, as it’s not designed to apply the amount of force required to unfasten it.

What is the difference between an impact driver and a hammer drill?

How an Impact Driver Works

Some of you might wonder if an impact driver and a hammer drill are the same things; they both deliver a rapid succession of blows, after all. On top of that, the hammer drill is also known as “impact drill”.

Well, the main difference lies in that an impact driver has an impact function, whereas a hammer has a hammer function. Sounds a bit obvious, doesn’t it?

As we’ve mentioned several times before, the impact drives uses the rotational impacts of the hammer against the anvil to loosen or fasten large screws and other fasteners. The hammer drill, on the other hand, has a different mechanism that combines rotary motion with a pulsating hammering action on the head of the drill.

Since hammer drills are used to bore through hard and brittle materials such as brick, masonry, and concrete by pulverizing it without damaging it, they’re more powerful and precise than impact drivers. Some hammer drills also have a feature that allows you to switch off the hammering action and use it as a conventional drill for screwdriving.

Basically, impact drivers are mainly designed to drive certain kinds of fasteners through metal and hardwood, but they lack torque control and precision. You need to be careful when operating them because you risk stripping the screws and damaging the surface you’re working on. Impact drills are used to make precisely placed holes of the specific size you require.


Impact drivers are highly useful power tools when it comes to driving long thick screws into hard materials, and also for unscrewing tight fasteners with ease. They’re not the same as impact drills, which are used to drill holes in dense materials.

To be used in a wide array of jobs, this power tool can tackle different tasks ranging from automotive projects to DIY home repairs such as building decks or making some cabinets.

Now that you know how an impact driver works and why it can be useful to have one, you might want to consider adding one to your arsenal!

Liam Weissman

Hello and welcome to PowerToolGenius! My name is Liam and for the last 9 years, I have worked extensively with various power tools and accessories. I have tested hundreds of different brands and models and understand the industry extensively and have been working with tools my entire life!

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