An impact wrench is a vital tool you can use to perform various assembly, repair, and maintenance tasks. The amount of torque you require in an impact wrench varies depending on the type of job you are performing. However, applying too much or little torque can lead to undesirable outcomes. Regardless of the task, this guide will help you determine how much torque you will need for an impact wrench.
How Much Torque Do I Need For Impact Wrench?
When purchasing an impact wrench, one of the most important things to consider is torque. Torque is the force that causes the drive of an impact wrench to rotate. The torque the impact wrench delivers should be sufficient to complete the task you are performing. For instance, if you want to remove lug nuts from car tires, you will require around 350 Nm of torque.
On the other hand, you will require about 600 to 1000 Nm of torque for large projects such as constructing rail. An impact wrench with adjustable mechanisms would be ideal for applications such as car assembly. It is mainly because car assembling involves various components that require varying levels of torque.
If you want to tighten large-sized screws, you should adjust your impact wrench to produce a torque range of 30-3000 Nm.On the other hand, if you want to install or remove rims from your car tires, a torque of 100 Nm is sufficient. If you get it wrong, choosing an impact wrench will probably generate a torque more or less than what you need.
Your selection should depend on the working torque of the wrench and not the maximum torque it can deliver. In most cases, the torque of an impact wrench depends on its type, and you can use one of the following impact wrench types depending on your application and torque requirements.
Hydraulic impact wrench
The torque output of a hydraulic impact wrench is higher than that of impact wrenches that use air or electricity. It comes with a calibration that measures the amount of torque you need to apply when fastening or loosening bolts or screws.
Hydraulic impact wrenches differ from other powered wrenches as they generate torques using hydraulic pressure and have a self-ratcheting mechanism. They are versatile and flexible in terms of movement, and you can use them to fasten and loosen nuts even in tight spaces.
Usually, their design fits varying joint widths and heights. They allow you to use varying kinds of control heads, further improving the operation versatility. However, they are suitable for heavy industrial conditions for large bolts requiring a high precision level.
The torque output of a hydraulic impact wrench depends on the volume to retract and extend the hydraulic cylinder, the flow of the pumping unit, and the level of turn-of-nut per stroke of the cylinder. If you increase the pump flow rate, there will be an increase in the speed of operation.
Pneumatic impact wrench
It is an impact wrench that depends on compressed air for operation. You can use this device without having malfunction issues as it does not have electric components. A continuous supply of compressed air ensures continuity of operation without overheating.
The rotating elements in these wrenches are the only heat source, but the heat vanishes quickly because of the compressed, pressurized, circulating air. It generates a torque range of 300 to 2200 Nm, making them suitable for assembly lines and manufacturing plants. It is smaller than other impact wrenches and is suitable for applications requiring less torque.
However, these impact wrenches are less adjustable as you can only adjust the torque using either of the following methods:
- Controlling the tool pressure- You can adjust the torque by regulating pressure using a pressure regulator. This method is ideal for impact wrenches that lack a built-in air regulator. However, it is quite challenging because you need to pass pressure from the compressor via the air regulator and the impact wrench. If your impact wrench has this feature, you can directly use the regulator to adjust the torque.
- Controlling line pressure- You can adjust the torque by regulating the air compressor’s pressure.
Electric impact wrench
These wrenches use electricity as their power source and do not use additional pumps or air supplies. There are two variants of electric impact wrench; corded impact wrench and cordless impact wrench. Cordless wrenches are portable, allowing you to carry and operate without entangling cords. They use lithium-ion or cadmium batteries that start from 18 to 28 volts.
However, they drain very fast and will require regular replacement. On the other hand, the corded variant only requires plugging into a power source. It has an electric motor fixed at the back of the wrench. With the electric impact wrench, the speed of operation is higher than that of a pneumatic wrench and ensures better torque control.
Also, you do not need to have an air compressor, making it pocket-friendly to purchase and operate. However, you cannot use it if you live in remote areas with no electricity grids. Besides, there are many cases of overheating because of the excessive movement of the mechanical parts. A cordless impact wrench can easily generate a torque output of more than 250 Nm.
How to increase the torque of an impact wrench
There is no standard torque for each application. However, it doesn’t mean that you will require a different impact wrench for every task you are performing. Although adjusting your impact wrench’s torque configurations is not advisable, you can adjust your torque to achieve your desired results.
However, you should only do this if your impact wrench has a maximum torque, failure to which may result in complete damage to the wrench. If you want to increase your impact wrench torque, follow the below step-by-step procedure:
- Dismantle the impact wrench using a 5/32″Allen wrench, extract the backplate, and then remove the cylinder and motor.
- Using a Dremel, create new ports on your cylinder, but you need to be careful not to waste too much metal. Repeat the same procedure for both the front and the rear cylinder.
- Access the endplate by opening the exhaust ports on the cylinder. Enlarge the inlets ports, make sure they have similar sizes, and leave the holes for the screws.
- Cut the paper gaskets to match the new ports
- Thoroughly clean everything and assemble the impact wrench
Your impact wrench torque should improve and allow you to carry out more high-torque jobs. However, the improvement will only be slight, so you can’t rely on this method if you want a significant improvement in torque.
Effects of too much torque on nuts
Applying excess torque on lug nuts can damage the central part and even cause breakage or warping of brake rotors. Usually, it is because the lugs of a wheel tend to bend when you apply too much force. Overtightening some lug nuts may lead to uneven tightening against the surface of the brake motor.
Uneven tightening may lead to situations that are hard to undo, such as the rotor distorting or balancing off-center. In other instances, applying too much torque may not lead to faster loosening or tightening of bolts and nuts. Typically, over-torquing can crack or break the nuts, distorting them fully.
Factors to consider when buying an impact wrench
Before purchasing an impact wrench, there are several factors you need to put into consideration to ensure an easy and convenient operation.
- Size- you need to keep in mind the size of bolts you will be working on.
- Power source- you should consider whether your wrench uses electricity or batteries.
- Chuck size- Chuck is the clamp that rotates and holds a driving bit. Its size helps determine how powerful the drill is and the biggest drill bit you will put into the drill.
- Power- It is advisable to go for an impact wrench to control the torque.
Frequently asked questions
Which size impact wrench is ideal for removing lug nuts?
An impact wrench ideal for removing nuts should measure ½- inch or ⅜-inch. Both sizes offer sufficient power required to remove even the toughest lug nuts without over-torquing.
How big of an air compressor do I need for my impact wrench?
Most ½-inch impact wrenches require an airflow rate of around 5.0 CFM at 90 PSI. It should offer an airflow rate of 6.25 to 7.5 CFM at 90 PSI when it comes to convenience and efficiency.
What happens if I under torque my bolts?
Generally, torquing deform the bolt, resulting in lower clamping force. Using a well-calibrated torque tool helps you avoid the risks of a too loose or too tight bolt or nut.
The above guide will help you determine the amount of torque you will need for your impact wrench and the different wrenches you can use to carry out different kinds of tasks. Purchasing an impact wrench with adjustable torque configurations helps you avoid the hassle of using different impact wrench for different jobs. Although it is challenging, you can also increase your impact wrenches torque using the above tips.