A pneumatic impact wrench is one of the power tools used to tighten and loosen lug nuts, bolts, and fasteners. With a high rotational torque, it can deliver the best results.
However, CFM and air pressure are two of the most important requirements for an impact wrench. But how many impact wrench CFM requirements do you have for your project?
The CFM requirements for your impact wrench will depend on several factors, including the size and power of the tool and the type of work you will be doing.
Generally, smaller impact wrenches with 1/2-inch drives typically require around 5-6 CFM at 90 PSI, while larger, more powerful wrenches with 1-inch drives may require up to 50 CFM or more.
Yet, in this article, I’ll explore the CFM requirements of impact wrenches and provide a helpful chart to guide you in selecting the right air compressor.
What is CFM?
CFM stands for cubic feet per minute, a unit measuring the airflow rate. For instance, 0.1 CFM indicates a flow of 0.1 cubic feet of air per minute.
However, you must not confuse CFM with PSI. Pounds per Square Inch measure the number of pounds of pressure in a square inch. The air pressure results in compressed air.
For instance, the output of an air compressor may be around 100 PSI. It indicates that the compressor delivers 100 pounds of air pressure per square inch.
Air compressor size and impact wrench
How will you decide on the air compressor size for your impact wrench? A standard air compressor is available with 4-5 CFM and 90PSI. With this compressor, you can run your ½ pneumatic impact wrench.
The compressor’s capacity is about 20 gallons, preventing delays between your tasks. Before deciding on the air compressor, you must learn about the tank size and minimum CFM.
Although CFM (flow of air) is important, you cannot overlook PSI. Both these parameters are important to ensure the good performance of your air-driven impact wrench.
How will you identify the right CFM for your impact wrench?
The size of your impact wrench is highly important when determining the CFM. Thus, the larger impact wrenches need more air.
There is no particular rule on identifying the CFM requirements and impact wrenches. But a minimum of 6-gallon with a 4 CFM air compressor is recommended.
Similarly, the size of your impact wrench will enable you to know the air pressure needed for the tool.
Impact wrench size- ¼-inch
Applying a high amount of air pressure for your 1/4-inch impact wrench is unnecessary. Regular air compressors are designed to deliver 1 to 1.5 CFM. However, it is more than enough for your 1/4-inch impact wrench. Although you can apply high air pressure, you can avoid it.
Impact wrench size– 3/8-inch
Your 3/8-inch impact wrench needs a good amount of power. You should have twice as much power. Thus, you should purchase an air compressor with a 3 to 3.5 CFM power rating. But can you use machines with a lower rating? Professionals have found no significant problems with air compressors with lower CFM (around 2.5 CFM).
Still, we think setting a slightly higher budget for air compressors is better. Thus, the CFM for a 3/8-inch impact wrench should not be less than 3.
½-inch impact wrench
Most commonly, workers like to use 1/2-inch impact wrenches for their projects. ½ inch is the average size of the impact wrench. Thus, buying air compressors for wrenches of this size is essential. You can rely on 3-3.5 CFM for your ½-inch impact wrenches. But you can invest in air compressors with 4 CFM for better results.
Read: Should You Get 3/8 Or 1/2 Impact Wrench?
1-inch impact wrench
Professionals in the construction industry need to use 1-inch pneumatic impact wrenches. As the impact wrench is big, you must choose a highly powerful air compressor. Thus, the minimum CFM for this compressor must be at least 9. Although it is costly, you must invest in it for the desired performance.
While dealing with a rusted and frozen fastener that needs high torque, you can choose a multi-stage air compressor. A standard single-stage air compressor is available with an air pressure rate of 175PSI. Using this air pressure, you can remove stubborn lug nuts.
Another thing to be noted is SCFM. 1.2 CFM equals 1 SCFM. Thus, 2.6 SCFM has a value identical to 3.12 CFM. Your 2.6 CFM air compressor must not be used for your 8 CFM pneumatic impact wrench. It is mainly because of the absence of 4.88 CFM.
But, you can raise the CFM level of an air compressor to maintain normal functioning. You have to check the CFM ratings to buy your air compressor. This factor is important in your regular use of the pneumatic tool. It is also important to make sure that your air compressor can give your impact wrench good air.
Impact Wrench CFM Requirements Chart
| Impact wrench size | CFM |
|---|---|
| Impact wrench size- ¼-inch | 2.5-3.5 |
| Impact wrench size- 3/8-inch | 2.5-3.5 |
| ½-inch impact wrench | 3-3.5 |
| 1-inch impact wrench | >9 |
Should you focus on other aspects of air compressors?
Some manufacturers try to design smaller, more lightweight air compressors while maintaining adequate power. Other manufacturers focus on the size to identify the compressor’s power. You should also check the air compressor’s tank size used for your impact wrench.
However, the tank size is not much significant factor when using the air compressor for an impact wrench. Still, having a 4-gallon tank for your impact wrench is safe.
Air compressor size based on your project types
You need to base your decision on the type of project to be managed by you. For instance, air compressors for painting a car should have a high CFM volume to paint your vehicle. CFM requirements will differ when you consider using the compressor for your impact wrench.
You can read manufacturers’ instructions to identify the right CRM rating for your impact wrench.
Why is CFM important for impact wrenches?
CFM is important for impact wrenches because it tells how much air flow the tool needs to work well. If the CFM is too low, the tool might not work at full power, making work take longer or less effective. If the CFM is too high, energy can be wasted, and costs can go up.
Can I use an air compressor with a lower CFM rating than my impact wrench requires?
If you use an air compressor with a lower CFM rating than your impact wrench needs, the tool may not work as well, get too hot, and wear out faster than it should.
Can I use an electric impact wrench instead of an air-powered one?
Yes, there are electric impact wrenches that don’t need an air compressor. But they might not be as strong as impact wrenches powered by air and might not be good for heavy-duty work.
By knowing how many cubic feet per minute (CFM) your impact wrench needs and choosing the right air compressor, you can make sure your tool works at its best and get your project done quickly and well.
Final Words
Understanding an impact wrench’s CFM needs is critical to ensure optimal performance. By selecting an air compressor that can supply the right CFM for your wrench, you can avoid inefficient and potentially dangerous work conditions caused by underpowered or overpowered operation.
While choosing an air compressor, consider these considerations and the air tools and equipment you’ll use in conjunction with your impact wrench.
Finally, choosing the correct air compressor and ensuring adequate CFM delivery can assist in extending the life and efficiency of your impact wrench and improve overall productivity and work quality.
I hope this information has helped you better understand impact wrench CFM requirements and make an informed selection when selecting an air compressor for your needs. Always put safety and correct equipment use first in your job efforts.
