Finding a reliable torque wrench calibration service can be tricky. Without it, you can’t be confident your torque tool is delivering precise tightening or loosening of bolts, nuts, and other fasteners.

Let’s look at how calibrating your torque wrenches regularly can help you maintain quality control standards, safety, and compliance with the latest ISO standard for torque calibration — ISO 6789-1:2017.

What is a torque wrench?

Torque wrenches are specialised tools used in industries such as automotive, aerospace, and construction. They ensure all connections are secure by meeting the desired torque value.

Common torque wrench drive sizes include ¼-inch, 3/8-inch, 1/2-inch, and 3/4 to 1-inch. The smaller drives are suitable for lighter applications such as socket sets and smaller nuts and bolts used in computers and electronics. They also allow you to access tighter spaces with ease.

If you’re working with heavy-duty fasteners or bulky machinery, you’ll need a torque wrench capable of handling higher levels of torque, such as a ¾ to 1-inch drive.

Selecting the right size torque wrench for your job is paramount. Too big and it can damage the nut or bolt. A torque wrench too small for applying the necessary torque can see you lumbered with inaccurate readings.

Does a torque wrench need calibration?

In a nutshell, yes! Like all test instruments, torque wrenches are only safe when used correctly and regularly calibrated. Torque wrench calibration should be a critical part of your quality management strategy, especially for industries like aerospace who can’t afford any lapses in safety and accuracy.

However, routine calibration of your torque instruments is a worthwhile investment for many reasons, not just meeting compliance and safety standards. Even if your top priority is product reliability and safety, torque wrench calibration maintains tool precision, prevents component damage, and extends its lifespan, reducing the requirement for replacements and repairs.

Do digital torque wrenches need to be calibrated?

Digital torque wrenches use electronic sensors that provide greater accuracy than mechanical ones. However, they still lose accuracy and reliability over time due to wear and tear, mishandling, and environmental factors.

These digital torque tools cannot self-calibrate, and require the help of an external tool and trained engineer to undertake the correct procedure, so your digital torque wrench performs at its best.

Can you calibrate your own torque wrench?

Just like heart surgeons and underwater search and rescue teams, calibrating a torque wrench relies on specialised equipment and expertise. While cutting corners and saving money may seem tempting, it’s not recommended.

Using professional calibration services gives you the peace of mind your torque wrenches have been calibrated correctly. You’ll also be issued with a calibration certificate to prove proper testing has been carried out to either national (traceable) or UKAS standards. Did you know AML Instruments is both UKAS ISO 17025 and ISO 9001 accredited for temperature calibrations and weigh scales and balances calibrations (none automated weighing equipment)?

Close-up of hands operating a torque testing machine with a blue in-line torque transducer and a red digital display showing a torque value of 114.81.

How long is a torque wrench calibration good for?

There are many things to consider when asking how often to calibrate a torque wrench. These include:

Frequency of use.
The closeness to the maximum capacity the torque wrench is used. For instance if a 300 Nm is always used at 250 Nm or above, it should be more often than if it was always used at 30 Nm.
If the torque wrench been overloaded by 25% or more.
Conditions in use and storage.
Previous calibration results. Before your usual calibration frequency, you should get your torque wrench checked to see if it is close to the maximum allowed errors.

In general, our answer to how often you should calibrate a torque wrench would be every 12 months or every 5000 cycles (whichever comes first). However as you can see from the above list, there are times when this calibration frequency should be reduced.

How to check if your torque wrench is calibrated

There are numerous tell-tale signs indicating whether or not your torque wrench is calibrated properly. Look for the following:

Your torque wrench is delivering inconsistent or erratic readings.
Your torque wrench is not clicking or signalling when it’s reached the desired torque level.
Your torque wrench is not holding the desired torque level.
Your torque wrench is bearing excessive wear and tear or damage. You should also get your torque wrench calibrated if it’s been dropped or mishandled.

If you notice any of these anomalies, it is recommended you have your torque wrench calibrated as soon as possible to ensure its accuracy, reliability, and safety.

What if my torque wrench fails calibration?

Wherever possible, your torque wrench will be adjusted to bring it back within the requirements of ISO 6789. We will always record “As Found” results and “As Left” results if adjustment was necessary.

Where can I get my torque wrench calibrated?

Can’t be without your torque wrench or torque screwdriver? At AML Instruments, we make the entire process efficient and hassle-free.

We offer a mobile torque wrench calibration service across the entire UK covering all torque wrenches and torque screwdrivers up to 400 Nm. Larger torque wrenches can be brought back to our calibration laboratory in Lincolnshire — you can collect these during your calibration visit.

Additionally, you can send us your torque wrenches to be calibrated. As standard, our turnaround time for offsite torque wrench calibration is five working days, with a 24-48 hour express service also available.

For emergencies, we even provide a “Calibrate While You Wait” calibration service. All we ask is you please give us a call or email in advance to book either of these express services.

Unless requested, our torque wrench calibration service is based on the requirements of the latest ISO standard for torque calibration ISO 6789-1:2017.

However, our torque calibration services aren’t solely limited to torque wrenches. We also calibrate other torque measuring devices, including bottle torque testers and torque screwdrivers. All enquiries are responded to within 2 hours — why not put us to the test today?

Close-up of hands adjusting a torque wrench on a piece of torque testing equipment with a vertical metal rail and electronic instruments in the background.

The Torque Wrench Calibration Service You Need