Last Updated on August 28, 2022 by Barry Gray
When fastening and loosening bolts and nuts, and even lug nuts, there is no easier way than using an impact wrench and a torque wrench. What is the difference between an impact wrench and a torque wrench? When do you use a torque wrench and not an impact wrench?
A torque wrench is a pre-calibrated and precise tightening tool used for tightening nuts or bolts to a specified tightness. Don’t use a torque wrench for loosening bolts. An impact wrench loosens or fastens any bolt, nut, or lug nut, but it cannot accurately tighten to a specific torque setting.
Let us explore the uses and differences between a torque wrench and an impact wrench. We will also look at the types of torque wrenches on the market, and as a bonus, we will look at the difference between an impact wrench and an impact driver.
When Do You Use An Impact Wrench?
Most people have to loosen a bolt or nut sometime in their life. Whether you change a flat tire on your car or maybe put that custom-made cupboard into your new home somewhere, you will find yourself in need of a tool that can make it easier to deal with the bolts or nuts.
Mechanics use pneumatic impact wrenches in professional garages, making that iconic sound of loud whirring as they loosen or tighten lug nuts on wheels. Cordless electric battery-powered impact wrenches are now available for the average person. Although they are still noisy, they quickly fasten and loosen nuts and bolts.
Impact wrenches get power from the hammering motion generated by a rotating mass inside the tool. The rotating energy then gets delivered to an output shaft with a socket. The hammering force causes incremental turning until the nut is completely loose, and then it will spin freely.
Remove or tighten nuts and bolts; use an impact wrench. The power generated by an impact wrench allows any person to use it with minimal effort.
Impact Wrench Vs. Impact Driver
An impact wrench and an impact driver sound almost the same and are nearly the same. The difference is that an impact wrench has a higher torque output allowing for heavier duty work. The impact driver gets used for lighter torque jobs where the force needed to drive in a screw or bolt is less than what you would need when using an impact wrench.
Another main difference is that the impact driver has a ¼ inch hex opening, whereas an impact wrench has an ½ inch opening. Therefore, having the correct socket size opening is essential since they are not interchangeable.
Can You Adjust Torque On An Impact Wrench?
The design of an impact wrench is to act as a hammer, but instead of downward force, it has a rotational force. The impact delivered by the hammering motion is therefore not adjustable since maximum output forces get sent with each rotation. Therefore, the end torque value is not the end goal of an impact wrench.
Here Are Two Adapters You Can Use To Torque An Impact Wrench.
- Torque sticks: Use torque sticks to limit the power delivered by the impact wrench. A torque stick dampens the rotational motion to a specific rating in feet per pound (ft./ lb) or feet per inch (ft./inc). Torque sticks are limiting extension bars that fit between the impact wrench and the socket. They range from 65 ft. / lb to 150 ft. /lb
- Torque limiters: Dynamic torque limiters are more expensive and complex. Torque limiters and adapters are connected between the impact wrench and the socket and deliver precise and accurate results. You can find torque limiters that get pre-calibrated for a specific torque value.
Mistakes To Avoid When Using An Impact Wrench
- Over-Tightening: It is easy to overtighten when using an impact wrench. It will continue to tighten for as long as it’s triggered. Untrained persons underestimate the power of an impact wrench.
- Damaging threads: It is better to start the bolt or nut with your hand, making sure the tread is not cross-threading. The impact wrench will cause damage instantly with its’s powerful rotations.
- Mismatching sockets: Impact wrenches are not compatible with regular sockets and can cause slippage and damage when under strain. Use the correct sockets for your model.
- Incorrect torque strength for the job: All impact wrenches will have a torque rating. Make sure you do not damage your impact wrench by performing tasks outside its specifications.
When Do You Use A Torque Wrench?
The function of a torque wrench is to prevent overtightening. The average person might not realize it, but some torque settings apply to tightening bolts, nuts, and other fasteners in specific use cases.
Standard wrenches and tools are OK to use for fastening bolts, nuts, studs, and screws, but use a torque wrench when you need to tighten to a specified value.
A torque wrench is a wrench that applies the correct torque strength to a fastener. It has an adjustable scale to gauge the power needed to tighten the nut or bolt correctly. The torque wrench will activate by either producing a clicking sound or displaying it when the appropriate torque level gets reached.
When you start tightening to a specific torque setting, and the torque wrench activates immediately, your bolt or nut is already over the threshold of the torque wrench. You should loosen that bolt or nut and start over with the tightening process.
Handle your torque wrench carefully since it is a high-precision tool. Set the device to its lowest setting before storing it. Recalibrate the device after 5000 or more uses or if you dropped the wrench accidentally.
Here is a video of how to use your torque wrench:
Four Basic Types Of Torque Wrenches:
- Beam or Deflection: a mechanical system where a pointer hovers over the torque scale. The force applied to the handle causes a deflection to be visible on the scale.
- Dial Indicator: also a mechanical system where a pointer hovers over the torque scale. The force applied to the handle causes movement of the dial.
- Clicker: A movable ring around the base of the handle on clicker wrenches allows you to establish the exact tension you wish to apply to a nut or bolt. Tightening to the specified torque causes the ratchet mechanism to click loudly, indicating that you should stop.
- Digital: Digital torque wrenches are more expensive but the most accurate. An electronic strain gauge inside the handle display on a LED screen
You will only use an impact wrench for loosening tasks and a torque wrench for tightening jobs in a perfect world.
You’ll need to utilize additional adapters to change the tightening torque of your nuts and bolts because impact wrenches don’t offer a torque adjustment option. Torque wrenches offer adjustment settings to tighten bolts and nuts correctly but using them for loosening jobs is not recommended.