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Pneumatic impact wrench buying guide

Guide written by:
Sebastian, self-taught DIY-er, Exeter

Sebastian, self-taught DIY-er, Exeter

177 guides

Available in any repair shop, the pneumatic impact wrench, also known as a bolt-on or driver, is the must have tool for the avid mechanic! Pressure, air flow, impacts per minute, torque or spiking force in Newton-meters (Nm). Here are all our professional tips for choosing the right one!

Important features

  • Pressure
  • Air flow
  • Spiking torque

How does a pneumatic impact wrench work?

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The pneumatic impact wrench, also referred to as a driver, is like a screwdriver - if you squint a bit! It is designed to bolt and unbolt bolts either screw or unscrew screws.


The pneumatic impact wrench operates by supplying compressed air supplied by a compressor. The impact wrench's screwing force is driven by a striking mechanism composed of an engine, an anvil, a hammer and a spring.


Especially useful for mechanics using high torque tightening, the impact wrench is the portable pneumatic tool you see being used to remove your car's wheels when you change your tires or brake pads.


Designed for clamping, any precision task will need to be completed with a torque wrench - to ensure a good tightening.


To avoid buying one pneumatic driver for each different diameter, the sockets are interchangeable . Genius!

What are the characteristics of a pneumatic impact wrench?

ManoMano

A pneumatic impact wrench is selected based on different factors, the two main ones being the spiking torque and the impacts per minute.

Torque is measured in Newton-meters (in tribute to Sir Isaac Newton for his work in classical mechanics) and this value represents the spiking force that will be applied to the bolting and unbolting action. To give you an idea, a wheel bearing is tightened to about 120 Nm (Newton meters) - a bearing is not just a hibernating animal, it is also a type of fastener used in mechanics!

To avoid damaging these infamous fastener's heads, consult the torque chart to get a better understanding of the torque needed - in comparison to the diameter.

Avoid under-charging the wrench, otherwise you will be finishing the operation by hand.

The impacts per minute determines the tightening speed. The higher the number, the more ttoque is applied to the offending screw or bolt.

Other factors to help you make the right call: 

  • The tool's weight is important for better maneuverability;
  • The anvil's coating;
  • The ergonomics of the handle;
  • The spiking speed relative to the impacts per minute;
  • The sound level, expressed in decibels (dB);
  • A Power regulator to accommodate different bolts;
  • A variable speed trigger;
  • The spiking torque - for maximum loosening force;
  • An exhaust vent to prevent backlash from the user.

Pneumatic impact wrench and compressors: air flow and pressure


Since the driver operates with an air supply from a compressor, it is crucial to match the energy provided with the requirements of the tool.

To accomplish this, pay close attention to:
 
  • The operating pressure expressed in bars (B) needed by the wrench;
  • The required air flow rate expressed in liters per minute (l / min).
 
The compressor must provide these essential requirements to obtain optimal use of the wrench.

Advice on choosing a pneumatic impact wrench



The reservoir's volume will determine the tool's time of use, since it has no engine in need of re-pressurizing the air. 


A minimum of 50 liters (l) is required for the smaller of the pneumatic impact wrenches.


The pipe's diameter impacts the flow, so always remember to follow the manufacturer's recommendations for each tool to get maximum use! Remember to check for the right connection sizes!


Do not attempt to use non-shock sockets as they will break on the very first impact. Those sockets are fixed via a 1/2" square connector. Shock sockets only! 


Always plan according to the intended task and the recommended boltage settings to be sure to get the right torque, otherwise your pneumatic impact wrench can be over or under-charged and can result in damage or frustration. 
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Guide written by:

Sebastian, self-taught DIY-er, Exeter 177 guides écrits

Sebastian, self-taught DIY-er, Exeter

Redo a roof with wooden beams? Check.
Advise Mister everybody in the DIY shop? Check.
Redo the bathroom plumbing? Check.
Fit together, build the walls, paint a partition, throw my hammer in a rage thinking that it will fix the problem? Check.

The DIY motto ? Learning is better than delegating… well, it's also a question about your wallet! The satisfaction? The beer at the end of the job!
What do the best have in common? The influence of Gyro Gearloose, Mac Gyver and Carol Smiley depending on your generation, a good dose of curiosity, a average hand-eye coordination and a taste for risks… and if it doesn't work, try again! Advise you? I'll do my best!

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