Impact driver vs Impact wrench : What’s the difference? See our comparison list below for an overview on what sets these two tools apart.
The most important difference between an impact driver vs impact wrench is the power, or torque they provide. If you’re uncertain whether to use an impact driver vs impact wrench, this article should be a valuable guide. We’ll be discussing the similarities and differences between these tools, their applications, how they work, and much more.
Impact Driver vs Impact Wrench
I’ll be discussing each of these tools in detail, but let’s start by examining the differences. If you’re not that knowledgeable about impact tools, they may appear to be the same. They certainly look very similar.
When we try remove a bolt or screw that just won’t budge, the best way to help things a long is to knock the back of the wrench or screwdriver with a hammer. This counteracts against the friction and allows you to keep turning. Both impact wrenches and drivers do this for you by providing a mechanical impact. If the driver experiences any type of resistance, it will knock, like you would do with a hammer. So what’s the difference?
As I mentioned in the introduction, the primary difference is power, measured in pound-inch or pound-foot. The metric unit for measuring torque is Newton Metres (NM). Pound-inch is usually used for impact drivers, due to their lower power rating. Impact wrenches, being more powerful, are generally specified using pound-feet. The units of measurement are easily converted 1 Pound-foot is equivalent to 12 pound-inches. If you have a measurement in pound-feet and want to know what this is in pound inches, you multiply the specified number by 12. Converting pound-inches to pound-feet, you divide the number by 12.
Because they are more powerful, impact wrenches are used mostly for nuts and bolts. Impact drivers are usually used to drive screws and low torque bolts.
As they are used different applications, impact wrenches and drivers have different drives. This being the drive end of the tool where you attach the bit or socket. Since torque wrenches are designed mostly to drive sockets, these tools are equipped with a ½” or ³⁄₈” square drive. Impact drivers have a ¼” hex-drive, into which you can insert any type of hex bit, like a screwdriver bit. Impact wrenches are always larger and heavier than impact drivers. They have larger motors and gearboxes to provide the extra torque needed.
Most homeowners won’t see much need for an impact wrench, they’re just too powerful for most household applications. If you try drive a screw, using an impact wrench, you’ll probably break the shank. Conversely, if you try use an impact driver to loosen a large bolt, it won’t have the required power. The tool will just stop when it encounters too much resistance. It should go without saying that impact wrenches are more expensive than impact drivers.
Impact Wrench | What’s it For?
Anyone who’s tried to remove a large, stubborn bolt will understand the importance of the impact wrench. No auto shop can function without one. In the past, impact wrenches were mostly pneumatic, using compressed air to provide the necessary torque. These days, even in large manufacturing plants, battery-powered (cordless) impact wrenches are the norm.
Impact wrenches are designed for heavy-duty work and are generally more robust compared to impact drivers. An impact wrench will often have a metal gearbox housing instead of the plastic used for light-duty tools. The gearbox is obviously much stronger, allowing the tool to handle higher torque settings.
So, how much power does an impact wrench deliver? Typically, impact wrenches have a variable torque range, starting at a minimum of around 200 foot-pounds (Ft-LBS) up to around 1,000 Ft-LBS for electric machines. Pneumatic tools can exceed 2,000 Ft-LBS. The Milwaukee M18 ½” 18V cordless impact wrench, arguably the king of cordless impact wrenches, delivers just over 1,000 Ft-LBS torque. To be exact, 1083.33 Ft-LBS.
Perhaps, simply mentioning torque specifications might not make much sense to most folk. For some context, let’s see how these tools perform when removing and tightening the lug nuts on your car. A standard sedan, uses a torque setting of 80 – 120 Ft-LBS for the wheel lug nuts, within easy range for even a low-power torque wrench. In fact, many impact drivers can deliver this kind of torque, but the ¼” hex drive doesn’t allow you to fit a socket to these tools. High performance cars, like Porsche and the like, can have a lug nut spec up to 450 LBS-Ft.
Impact wrenches are mostly used for auto repairs and heavy-duty manufacturing.
Impact Driver | What’s it For?
Impact drivers are small, lightweight tools. There isn’t much difference between an impact driver and a cordless drill. For driving smaller screws into material that isn’t too dense, a cordless drill with a variable power trigger may do just fine. The only real difference being the impact mechanism which helps when driving larger screws into or out of hard wood and metal. A drill may easily jam when the resistance is too high.
Impact drivers have a variable power output, usually with a switch for power modes and a variable speed trigger. The DeWalt 20V MAX (DCF885C1) is probably the all-time most popular cordless impact driver. This is mostly due to the reasonable price and good power output of 1,400 inch-feet torque (117 LBS-Ft). On the other end of the spectrum, the Milwaukee M18 Fuel (2853-20) ¼” impact driver is one of the most powerful, delivering 1,800 inch-feet torque. Milwaukee also manufacture a hydraulic, battery-powered impact driver (model: 2760-20). While this driver only provides 450 inch-feet torque, the power is sustained. This means that even when it encounters stubborn resistance,, the driver won’t stop. It may slow down but continues providing impact and rotation. A direct drive electric impact driver will switch off to protect the motor when the resistance becomes too much for the power provided.
Impact drivers are great for hardwood decking, metal construction work, and driving large diameter or long screws into dense material.
Maximum torque is the ‘peak’ amount of torque the tool outputs assuming the bolt is attached to a solid material. If a bolt is attached to something like a spring, then the force (torque) applied gets absorbed and is reduced via the laws of physics. There are many variables affecting how torque behaves in the real world. Wikipedia has a great explanation on the variables of torque.
“Nut-Busting” torque has NO agreed upon definition, but generally speaking, it refers to the capability of a tool (IE. impact wrench) to remove a bolt that has been tightened via a method other than with the tool being tested. In other words, if a bolt is tightened with a calibrated wrench at 1000 ft./lbs. and the impact wrench being tested is able to remove the bolt immediately after it has just been tightened — that becomes the measure (number) for “Nut-busting torque” assigned and marketed. But, this is misleading, because it’s far easier to remove a freshly tightened bolt as opposed to a rusted bolt on an old car. It sounds good though. The higher the number, the better in the eyes of unassuming consumers.
Read more about torque testing direct from Ingersoll Rand.
Additional Resources :
- Do I really need an impact driver? (Woodworkers Guild of America)