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Impact Wrenches

An impact wrench is commonly cordless (battery powered) or pneumatic (air powered) and is a power tool with a high torque output, that is used with an impact socket to deliver high levels of torque to remove bolts and fasteners by delivering rapid, rotating and forceful hammering impacts.

Impact wrenches are commonly found in garages and are used by automotive technicians to remove bolts on wheels and in engines, as well as in the construction sector for jobs like driving screws into wood and metal.

Frequently Asked Questions about Impact Wrenches

Can I use a cordless impact wrench for heavy-duty applications?

Yes a cordless impact wrench can be used for heavy duty work, such as automotive work, steel assembly and maintenance work. 

Modern cordless impact wrenches can deliver upto 3000Nm, which is ample for most jobs, and rivals most pneumatic impact wrenches for torque output. However, cordless impact wrenches require rechargeable batteries to function, which does make them useful for work in remote locations, but batteries will run out and will cause some downtime, which is why we recommend getting batteries with 5Ah+ to ensure longer run times.

In comparison, air powered impact wrenches run on compressed air and are less prone to overheating if used for prolonged periods every day. In addition they are lighter because there is less of an internal mechanism and no heavy battery attached to the tool, which makes them easier for the operator to use over longer periods.

Are impact wrenches suitable for home use?

Yes, impact wrenches can be used at home for various DIY projects, especially for tasks that involve bolts and nuts that require enhanced torque, such as changing the wheel on a car, lawnmower maintenance or loosening bolts on joists.

Cordless impact wrenches are probably the most suitable for home use because the batteries can easily be charged and it means that there is no need to store compressed air in the property.

In most instances, there is no need for industrial, high torque tooling around the home, so an impact wrench with around 400Nm of torque is likely to be able to handle most tasks.

Always ensure there is a spare battery, so that there is only minimal downtime when one battery runs out and needs recharging. 

What accessories are compatible with an impact wrench?

There are numerous accessories that can work with an impact wrench, including -

  • Impact sockets are an essential accessory because the socket grips the fastener and connects to the anvil of the impact wrench. This type of socket is designed to handle the shock and vibration that is generated from an impact wrench and is manufactured from chrome molybdenum steel, which is more pliable than chrome vanadium that standard sockets are manufactured from.
  • Socket extensions are used to reach recessed or hard-to-access fasteners, however, ensure they are impact-rated to prevent breakage.
  • Universal joints (U-joints) sockets allow access to bolts at angles, which makes them useful when accessing fasteners in tight or awkward spaces.
  • Impact bit holders and hex adapters enable the operator to use screwdriver bits or drill bits for lighter fastening tasks.
  • Protective boots to protect the impact wrench from grease and other substances it may come into contact with. 
  • Spare batteries.  We always recommend having a spare battery that is charged and ready to go, to prevent any downtime when the other battery runs out in a cordless impact wrench.
  • Impact adapters enable the operator to change the anvil size to fit a different socket drive size.

Are impact wrenches suitable for automotive work?

Yes, impact wrenches are commonly used in automotive settings for tasks like removing and tightening wheel lug nuts, loosening rusted or seized bolts and working on suspension components.

Impact wrenches are widely used in the automotive sector due to their enhanced torque output, which means that operators can loosen bolts quicker than with hand tools. However, most bolts in automobiles should be tightened to a specific torque measurement and whilst impact wrenches can tighten fasteners, we strongly recommend using a torque wrench to ensure that the fastener is tightened exactly to the manufacturers torque recommendation. 

Do impact wrenches come with variable speed settings?

Many modern impact wrenches feature variable speed controls, allowing the operator to adjust torque output depending on the task, which helps improve precision, avoid over-tightening and reduce wear on components. Variable speed on an impact wrench is usually controlled by two methods -

  1. The trigger, with the operator pressing lightly for low speed and harder for full speed.
  2. Electronic settings on the impact wrench, which enable the operator to select the speed the anvil rotates at.

What size sockets do I need for an impact wrench?

Socket size depends on what fastener is being loosened and it should match the bolt diameter and type, so a 17mm impact socket would match a 17mm fastener.

The drive size of the socket should always match up to the the drive size of the impact wrench, so a 1/2" imapct socket would fit on the anvil of a 1/2" impact wrench.

If we take the above two meaurements of 17mm x 1/2" impact socket, it means that the socket fits on 17mm fasteners and attaches to a 1/2" impact wrench.

Only impact-rated sockets should be used with an impact wrench because they are designed to withstand the twisting force and hammering produced by these tools without cracking. Impact sockets are available from 1/4" drive size, all the way up to 1 1/2", and the general rule of thumb is that the smaller the drive size the less torque the socket can handle. For example a 1/4" impact socket would be used for light duty loosening jobs, whereas a 1 1/2" impact socket would be used for industrial applications, such as removing heavy lug nuts on large machinery, like a truck or tractor.

What does torque rating mean?

The torque rating on an impact wrench refers to the amount of rotational force it can generate to tighten or loosen fasteners and is measured in Newton metres (Nm) or foot-pounds (ft-lb).

A torque wrench has two forms of torque that is measured -

  • Break-away torque (also known as nut-busting torque), which is a higher force used to loosen seized fasteners.
  • Fastening torque, which is the force used to tighten bolts.

The operator should always be cautious about the level of torque applied to a fastener and always adhere to manufacturer guidelines. If too much torque is applied to a fastener then it can strip threads and potentially damage components that are being fastened to. If too little torque is applied then bolts wont loosen. 

When fastening bolts, always finish with a torque wrench to ensure precise final tightening.

Can an impact wrench be used for tightening bolts as well as loosening them?

Yes, an impact wrench can be used to both tighten and loosen a fastener.

Impact wrenches are an ideal power tool to loosen seized or stuck fasteners quickly, with the hammering action transferring high levels of torque to the fastener without affecting the operators wrists. When using the tool to tighten fasteners there needs to be some caution taken from the operator because impact wrenches can apply high levels of torque very quickly, which can make it easy to over-tighten fasteners, damaging their threads and the components that they are being fastened to.

Why do impact wrenches have a hammering mechanism?

An impact wrench has a hammering mechanism so that it can deliver high levels of torque in a series of short and powerful bursts, rather than delivering it through a smooth and continuous rotation. Applying torque this way has several benefits - 

  1. Less kick-back is produced from the tool, reducing strain on the operators hands and wrists.
  2. Prevents stalling when the tool is under heavy load.
  3. Gradually breaks any resistance a fastener has by 'shocking' it loose.

Guides and Advice About Impact Wrenches

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