How To Test A Torque Wrench

The workplace of a friend of mine was the scene of an accident recently. An important piece of equipment had failed at the plant, causing the plant’s large production line to stop. Aside from the production line equipment being damaged severely, nobody was injured.

Through a study that lasted many days, the researchers were able to pinpoint the problem. Parts of a production line were damaged after a bolt securing a part to some equipment loosened and broke. A bolt was inserted incorrectly because a torque wrench used by an employee was out of calibration.

Regardless of whether you work in manufacturing, engineering, field service repairs, installation, or are simple homeowners, this incident taught us all an essential lesson: torque wrenches need to be properly calibrated to ensure precision and safety.

Types of Torque Wrenches

There are two types of torque wrenches: preset and adjustable. Preset wrenches are designed to work with fastening applications requiring only one set of torque settings, and they prevent the user from changing these settings. Conversely, an adjustable torque wrench offers an external torque scale that allows for quick adjustments in torque setting for various fastening needs.

You should be aware that these types of calibration differ slightly. The result will read “Go” or “No Go” for a preset or adjustable wrench whose torque will only be checked once. “Go” indicates a wrench is within tolerance, while “No Go” indicates it needs to be calibrated. A calibrated adjustable wrench will not give a “go/no go” reaction; it must be tested at least three times.

There are different types of torque wrenches available, besides the two basic categories of preset or adjustable. There are click, cam-over, break-over, and dial torque wrenches.

Click wrench

A torque wrench of this type is most commonly used. An engine-to-gear structure makes it possible for the head to ratchet. The torque selected is indicated by a distinctive ‘click’ sound.

Cam-Over wrench

The cam-over wrench prevents fasteners and bolts from being under or over-torqued. No matter the task or the operator’s skill level, this type of wrench provides accurate torque control without any hesitation.

Break-Over wrench

Torque wrenches of this type can be configured to fit a wide variety of head configurations and sizes. At the desired torque setting, the device switches over.

Dial wrench

Torque audits and torque measurements can be done using this type of device. A memory pointer on the dial helps to capture the torque applied to the fastener by measuring the main pointer on the dial.

Because precision is of the utmost importance, torque wrenches should be reliable and accurate. To that end, a quality torque wrench should conform to applicable safety and performance standards. You can then be certain that the torque wrench you have chosen is the right one for the job.

Calibration Of Torque Wrenches With Tools

The torque wrench will go out of calibration eventually if you use it frequently in the course of your work. The rule of thumb is to check torque wrenches every couple of years.

Checking whether a torque wrench is correctly calibrated requires a few common tools:

Torque Analyzer

The digital device is easy to use. The wrench comes with a display indicating whether or not it is calibrated accurately. Some analyzers are also capable of connecting to external torque sensors and have modes that can be used with a variety of tools. This analyzing tool will probably feel familiar to you if you are used to using your phone. A level surface is not necessary for all testers and analyzers. Some should be mounted to a permanent surface, like a workbench.

  • There are several options in the menu, including “Quick Test,” “Units,” “Mode,” “Setup,” and “Filter.”
  • Input the torque into the analyzer’s input first.
  • During that motion, an indicator is used to measure maximum torque until it is zeroed out.
  • A comparison is made between the scale on the wrench and the tester reading.
  • Check if a torque wrench needs calibration by following its prompts.
  • A calibration reading will be generated by the analyzer. As an added bonus, these readings can be quickly downloaded.

Torque Loading Bench

Torque wrench calibration can be done quickly and easily with this equipment. Manual loading is made easy with the wheel, which rotates clockwise and counterclockwise.

  • Make sure your loader is stable on a solid bench or another surface.
  • The torque wrench should be placed on the loading bench’s transducer.
  • You can prevent accidental adjustments through the presetting position, which will maintain greater accuracy.
  • Loading is easier with the large wheel, which can be turned both clockwise and counterclockwise.
  • The loading device assembly should be slid along the reaction bar. Clearance should be allowed for installing the torque wrench on the bar.
  • When testing the wrench, select the least powerful torque transducer.
  • You should align the handle of the wrench with the reaction bar’s length.
  • Attach the wrench to the torque transducer’s male square drive.
  • Explicitly slide the loading assembly along the reaction bar so the support spindle reacts against how the wrench is normally held. The reaction bar will become the wrench’s handgrip center.
  • Check that the ratchet orientation allows the wrench handle to move as freely as possible by the support spindle if the wrench is equipped with a square-drive ratchet.
  • Test the wrench while it is horizontally positioned on the spindle.
  • Securing the clamp plate is necessary before loading the equipment.
  • The torque wrench should be loaded smoothly by turning the handwheel.
  • The display instrument should be connected to a torque transducer that measures the applied torque. The wrench calibration will be verified by this.

You must regularly calibrate your torque wrench, regardless of the tool you choose. An attitude such as this will help you avoid potential problems down the road.

How to Maintain Your Torque Wrench

Each torque wrench eventually requires maintenance, regardless of its quality. Depending on how often the tool is used, it should be calibrated once per year, as with many other tools. It’s a good idea to periodically check torque wrenches for wear and tear or damaged components by keeping in mind the old adage, “Prevention is better than cure.”

Operators should monitor how often torque wrenches are used per day, how many cycles and hours it is used for, as part of a preventative maintenance schedule. Make sure to keep a log of this information that is easily accessible. 

Generally, torque wrenches should be serviced after approximately 100,000 cycles. The wrench should be removed from service if it shows excessive wear and tears.

Maintaining your torque wrench properly will prevent you from having to service it more frequently than necessary. Torque wrenches should be kept in a clean and dry environment in a case or other storage system. A cloth sanitized without chemicals or liquids works well for cleaning torque wrenches. Be sure to keep an eye on your torque wrench to make sure it’s still in working order, and have it professionally serviced if you spot any signs of damage or failure.

Calibration Of Torque Wrenches Is Important

I later learned that my friend and his colleagues were required to attend an in-house workshop to reinforce what they had learned: to use tools that are in good operating condition. Despite the inconvenience of checking the condition of your tools frequently, it is well worth the cost to ensure increased safety and efficiency.

An improperly installed bolt is of little use, after all. Inappropriate installation of a fastener can cause it to fail, possibly resulting in an accident. Your quality of work improves and the risk of an accident is reduced when you calibrate your torque wrenches correctly.

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