What is an impact wrench for?

What Is an Impact Wrench?

Impact wrenches are power tools designed to work like a wrench, loosening lug nuts, bolts, and fasteners. Due to their special anvil and hammer design, impact wrenches offer up massive amounts of rotational torque that other power tools can’t match, making them great for removing rusted nuts and bolts from old engines or for heavy construction work.

How Do Impact Wrenches Work?

Built with a specialised hammer and anvil design, impact wrenches transfer kinetic energy to the output shaft by having the hammer deliver fast concussive force to dogs on the anvil.

The hammer is built to apply a lot of force to the anvil and then spin freely, so as to build up torque for the next impact.

This sudden burst of force allows for massive amounts of torque to be applied to whatever is being tightened or loosened, allowing impact wrenches to twist off rusted bolts that have never seen a wrench in their life or speedily remove a wheel during a Grand Prix pit stop.

The other major benefit to this design is that while there is a massive amount of torque being applied to the anvil of the impact wrench, you don’t feel all of it, because you aren’t dealing with a rotational force from the motor, only the hammer mechanism is.

Different Types of Impact Wrenches

Impact wrenches come in various forms and in every standard socket drive size, with 1/4, 3/8, 1/2, 3/4, and 1-inch being the most common. For heavy construction work you may also see 1.5 inch up to massive 3.5-inch impact wrenches that are built for two-person operation and have a maximum torque output of upwards of 100,000Nm — these are slightly unnecessary for your home garage though.

While socket size is an important factor in choosing the right impact wrench, another huge factor is the type of power it uses, and they all have their own benefits and drawbacks.

Air Impact Wrenches

Pneumatic impact wrenches provide incredibly high torque and, despite great climbs in power for electric impacts over the last decade, are still unmatched in terms of power and speed. If you’re looking to do heavy duty work in a professional setting, an air impact wrench is your nut buster of choice.

Corded Impact Wrenches

Corded impacts sit comfortably in between air and cordless impacts in terms of power and portability. A corded rattle gun is something you’re going to want if you’re on a jobsite or in a workshop that is more likely to have accessible power outlets than compressed air and you need a bit more power than a cordless will get you.

You do also have to be mindful that extension cords will lose you some power, so if you’re not going to be working near an outlet and don’t need to be working for extremely long periods of a time, a cordless might get the job done just as well.

Cordless Impact Wrenches

You can’t beat the convenience and portability of cordless power tools and with battery-powered tech improving by leaps and bounds over the years, cordless impacts are looking all the more impressive.

While you won’t be able to match the power of an air impact wrench with a cordless, the ability to move around a jobsite without an air hose and compressor trailing behind you often makes up for it.

Cordless impacts are still no slouches when it comes to power. Milwaukee’s 1” D-Handled Impact Wrench will still get you 2,711 Nm (1999 ft/lbs) of nut-busting torque to work with, and you’ll get impressive power like this from their entire range of impacts.

When Should I Use an Impact Wrench?

While a standard wrench set can get a lot done around the house and on your car, there are some nuts that they just won’t bust, and this is the perfect time to pull out your Milwaukee ¼ inch and get serious.

An impact wrench is great for tough, rusted bolts that won’t budge, as well as for jobs that require a lot of loosening or fastening in a short amount of time. If you need to strip an engine for parts, perform heavy equipment maintenance, or tackle large-scale construction work, then the increase in efficiency from a standard ratchet to an impact gun is going to be massive.

Using an impact wrench at home will also speed up your tyre changes and let you fasten heavy-duty bolts with ease.

Tips for Impact Wrench Use

Here are some interesting features and things to remember about impact wrenches:

• Always use impact sockets when using impact tools, as they’re built with extra thick walls to handle the extreme power of the concussive impacts the tool produces, while standard power tool sockets will shatter under the stress
• When fastening with an impact wrench, remember to finish the job with a torque wrench, especially for sensitive fasteners that require specific torquing
• By the same token, don’t over-torque fasteners and bolts
• Impact wrenches and impact drivers are totally different tools. Impact wrenches are powerful variants of wrenches, while impact drivers are high-torque drills
• Brushless motors are more powerful and more efficient than brushed, but cost more, so choose the right kind for the job
• Some electric impact wrenches, such as tools using Milwaukee’s One Key technology, can have their torque improved by using the associated app
• Battery-powered impact wrenches will also gain improved performance from higher amp batteries
• Other names for impact wrenches include rattle guns, impact guns, impactors, and torque guns

Get More Torque at Repco

Repco stocks a wide range of impact wrenches and sockets, with brands like Milwaukee, Mechpro Blue, and Chicago Pneumatic bringing you high-torque solutions to all your automotive problems. Head into your local store or shop online to get serious about busting those tough nuts.