An impact wrench is a tool which uses a hammering system to turn bolts in quick, high power bursts. This movement allows large amounts of torque to be applied while being easier on bolt heads than a steady application of power.
An electric impact wrench replaces traditional air power with an electric motor. This motor is powered by electricity from a regular 110v wall socket.
How do electric impact wrenches compare with traditional air impact wrenches?
The main advantage of electric impact wrenches over air wrenches is their power supply: While the use of an air wrench is limited by access to a compressor, electric wrenches can be used anywhere with a nearby socket. This supply of power is continuous, allowing the tool to perform consistently over long periods of time while air tool power will fluctuate depending on the available pressure in the compressor tank.
Like electric drills, most electric wrenches come with a dial to adjust rotational speed. While it is possible to vary speed with an air tool by adjusting trigger pressure, this is much less precise.
On average a quality electric impact wrench will cost about 75% more than a comparable air wrench. If you would only use an air compressor to power an impact wrench purchasing an electric wrench may make better financial sense. Electric wrenches are only slightly heavier than air wrenches.
Where are electric impact wrenches used?
If it’s a large bolt that needs a lot of torque you’ll want to use an impact wrench. These wrenches mostly see use on automobiles and heavy equipment. While auto repair shops almost universally use air tools, the flexibility of an electric impact wrench makes it a popular tool for on-site equipment repair. Electric wrenches are also coming into use for construction: These tools can be used for interior work without having to run a hose outside to a gas or diesel-powered compressor.
What should I look for when shopping for one of these wrenches?
Aside from the hammering mechanism and the square drive electric wrenches are almost identical to electric drills: If you have a drill you like, you will probably like a wrench that uses a similar design.
Foot-pound power ratings are not standardized making comparisons based on them almost meaningless. Look at the motor’s amp rating instead: Two wrenches producing the same number of amps will have similar performance.
Can I use regular sockets and extensions with electric impact wrenches?
No. Sockets designed for use with a ratchet wrench are very brittle. Even mid-priced 1/2″ drive impact wrenches are available with power outputs exceeding 300 ft-lbs. The hammering action of an impact wrench places all that force into the socket in short bursts which can split or shatter the metal. The metal used in impact sockets is actually weaker than that used in ratchet sockets, but they have better flexibility for resisting these impacts.