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Impact Drivers and Impact Wrenches: What’s the Difference?

As cordless power tools become more and more popular, impact drivers and impact wrenches are making their way from the jobsite into the mainstream. They’re similar tools, and because of this, many folks don’t know much about what separates them, and what they’re best used for. Don't worry - your friends at WEN are here to help clear things up.

Construction

On the surface, impact drivers and impact wrenches share a lot of similarities. They’re often battery-powered and use a motor to drive a hammer and anvil. The hammer is a spring-loaded block that sits behind the anvil. When the motor spins, the hammer is forced up and over the anvil. When it clears the anvil, the spring causes it to snap back into place, colliding with the anvil and making it rotate. This rotating hammering action is what gives impact drivers and impact wrenches their characteristic loud rattling sound during operation.

20135 and 20107 impact driver and impact wrench

WEN 20V MAX impact driver, model 20135 (left), and 20V MAX impact wrench, model 20107 (right).

At this point, however, the similarities start to fade. Impact drivers are lighter-duty tools, and are very good at driving a lot of fasteners very quickly. They usually have a spring-loaded chuck on the end that can accept driver bits. These bits usually come with a 1/4” hex-shaped shank (which is the part that is inserted into the chuck), and are usually specially marked as being rated for impact use.

Impact wrenches are heavier-duty tools, and their anvils reflect that. Usually a solid piece of metal with a 3/8”, 1/2”, or 3/4” square drive, they feature either a hog ring (as on model 20107 shown above) or pin detent to attach to specially-designed impact sockets.

  • A hog ring is a C-shaped piece of springy metal that helps keep the impact socket locked on the anvil.
  • A pin detent is a spring-loaded pin embedded in the anvil that locks into a hole in the impact socket.

Whether a hog-ring design or a pin-detent design is best for you is a matter of choice. Generally, if you’ll be switching socket sizes often, a hog ring anvil may be easier for quick swaps. If you’ll be up on a ladder, or in a situation where one socket size is required and it needs to stay on no matter what, a pin detent anvil is probably the way to go. Regardless, ALWAYS use impact-rated sockets or accessories when working with one of these tools. Accessories that are not rated for impact duty could shatter under the extreme forces being applied, and could hurt you or others.

Ratings

Impact drivers and impact wrenches are usually rated according to three main measurements:

  1. Motor speed. Usually given in RPM (revolutions per minute), this is the maximum speed the motor can achieve. More speed means more fasteners driven or removed.
  2. Impact rate. This is often given in IPM or BPM (impacts or beats per minute, respectively), and represents the maximum number of times per minute the hammer hits the anvil. This is not always a clean multiple or dividend of the motor speed, because of the way the motor may or may not be geared.
  3. Torque. Perhaps the most important number of them all, torque is a measurement of the mechanical power a tool can put out at a certain speed. The physics of torque are a bit too complicated to go into here, but in short, the more torque a tool has, the tighter it can fasten a joint, or the more easily it can loosen a very tight joint. Impact drivers’ torque ratings are usually given in inch-pounds, and impact wrenches, which are much more powerful, the ratings are usually given in foot-pounds. If you’re using the metric system, either tool may be rated in Newton-meters. WEN impact drivers’ and impact wrenches’ torque ratings are based on our laboratory testing.

Uses

Depending on the job at hand, one tool may be a better fit than the other. Below are some common use cases.

Impact drivers

Commonly used to drive a lot of fasteners very quickly, or to work in tight spaces. These are great for driving lots of deck screws or small lag bolts, or torquing or loosening fasteners that aren’t extremely tight. Speed is the name of the game here - they deliver a lot of small blows very quickly, and can put out a decent amount of torque.

Impact wrenches

In contrast to impact drivers, impact wrenches are slower, heavier hitters, throwing haymakers round after round. Popular for automotive work to remove highly-torqued, rusty, or stuck nuts and bolts (or quickly zipping off wheel lug nuts), and for driving large construction fasteners (e.g. long lag bolts into pressure-treated lumber), they’re used when large amounts of torque are required.

Summary

In short, these tools, while they look pretty similar, have a lot of differences when you look under the hood. If you have any questions about what tool is right for you, or want to find out more about our 20V MAX line of cordless power tools, please give us a call at 1-800-232-1195 (M – F, 8 – 5 CST), or drop us a message here to talk to our friendly and knowledgeable technical support time. Also, check out some of our other handy articles about cordless power tools.

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