Whether it’s fixing up a car or maintaining various things around the house, mechanics – both amateur and professional – have been using torque wrenches in their work for years. The tool has become a highly-valued part of their arsenal, despite the simplicity of its function and the ease of its application.
A good mechanic knows what separates good equipment from bad equipment. No matter how advanced a tool may become – no matter how far it descends into techno-gadgetry – if it cannot do the job and do it well, it becomes obsolete. Despite this, engineering technology keeps moving forward at a rapid pace, producing some terrible bits of machinery and equipment along the way – and some that are actually pretty good.
One of the best innovations to come out of recent years is the digital torque wrench. While there are some who will no doubt scoff at its novelty and gimmickry, those who have had the privilege of using it will testify to its effectiveness. There are, however, a few kinks that may need to be worked out before you commit to buying one for yourself. In this article, we are going to go over everything you need to know about digital torque wrenches and answer as many of your questions as possible.
What is a Digital Torque Wrench?
Anyone reading this article probably knows what a torque wrench is. For those who don’t, here is a brief explanation of its intended purpose: a torque wrench is an integral part of a mechanic’s tool set, used to tighten nuts and bolts to a specified (torque) value.
It is a precision instrument that prevents damage from over tightening, while also preventing joints from falling apart. As such, torque wrenches are not only invaluable for applying the right amount of tension to fasteners, they are also absolutely necessary to ensure the safety and proper assembly of any piece of equipment.
There are many types of torque wrenches, and digital torque wrenches provide the exact same function, albeit in a different fashion. They have no moving parts as opposed to dial torque wrenches, and instead rely on an electronic sensor to calibrate the necessary amount of torque.
This is displayed digitally, and the reading is then stored on a memory stick, allowing it to be accessed from a computer. Storing the torque readings is also perfect for repeat jobs, when the exact same amount of tension needs to be applied to different joints and fasteners. Digital torque wrenches also make use of a visual indicator to signal when the right amount of torque has been applied.
How Do Torque Wrenches Work?
Torque wrenches – both standard and digital – are calibrated to apply a certain amount of tension to any joint or fastener. The exact amount is determined by the amount of force applied to the tool, as well as the length of the tool overall. (For reference, the formula for torque is: force x length = torque).
The handle of a regular torque wrench contains a built-in mechanical indicator that is connected to a calibrated scale. The scale provides a point of reference for the indicator and determines the maximum amount of torque necessary to tighten a bolt.
Torque wrenches also feature easy-to-read displays which dictate the readings. In the case of digital torque wrenches, these readings are subsequently stored for later use.
Torque wrenches can display different measurements: they can be calibrated to read in lb-ft (pound-feet); lb-in (pound-inches); or N-m(Newton-meters).
What is Torque Wrench Calibration and Why Is It Important?
Calibration of a regular torque wrench is vital to the proper application of the tool. It ensures that the wrench can provide proper, accurate readings in relation to industry standards. As such, having a torque wrench properly calibrated is not only vital for proper application, it also ensures its efficacy. Simply put, there is no use in having a tool that isn’t properly calibrated.
Fortunately, all torque wrench manufacturers are required to supply a calibration certificate, proving that the tool has had onsite torque calibrations and approved prior to distribution. Despite this, the accuracy of torque tools gradually decreases over time and with use, and it will need to be re-calibrated eventually.
Luckily, you can easily find a third-party torque wrench calibration service that can re-calibrate the tool for you, thus ensuring your continued peace of mind even after hours of use.
Do Digital Torque Wrenches Need to Be Calibrated?
All torque wrenches need to be properly calibrated before distribution in order to provide an accurate reading and optimal torque, including digital or electronic torque wrenches.
It becomes even more of a priority with digital torque wrenches, which often make use of analog-to-digital converters. These converters rely on a voltage supply in order to function properly, which needs to be calibrated in order to provide accurate readings – a drift in the voltage can lead to instability, which in turn leads to inaccurate readings.
That being said, electronic torque wrenches do have a built-in “self-check” function, which will alert you if their internal circuitry is damaged. This function is important for digital torque wrenches, which are highly sensitive to any and all forms of damage, from light dings and bumps to long drops.
Unfortunately, while the “self-check” function is very useful, digital torque wrenches do not include a “self-maintenance” or “self-calibration” feature. They require proper, regular maintenance and re-calibration much like any regular torque wrench, and their susceptibility to physical damage means you will have to take extra care with them than you normally would.
As with any torque wrench, make sure that yours comes with a torque wrench calibration certificate that proves that onsite torque calibrations have been performed.
How Often Should Digital Torque Wrenches Be Calibrated?
There is no set time frame for how long digital torque wrench calibration should last. In general, the factory calibration of your torque wrench should endure past several uses from your initial purchase, but it does depend somewhat on the type of torque wrench you use. (Again, make sure that yours comes with a torque wrench calibration certificate).
In general, the frequency with which you perform regular calibrations of your torque wrench – digital or otherwise – will greatly depend upon how often you use it. If you are a professional mechanic or you predict that you will use it often in the coming weeks, a good rule of thumb to follow is to have it re-calibrated after every 2,500 repetitions.
Otherwise, if you do not plan to use it regularly or with any amount of frequency, having your torque wrench re-calibrated once a year should be enough to ensure that the instrument maintains the accuracy of its readings.
Dos and Don’ts of Torque Wrench-Use
Like any tool on a mechanic’s belt, a torque wrench – whether digital or not – needs to be treated with the utmost care and respect in order to be useful. Some of the better models are also very expensive, and regular maintenance is crucial to ensuring that you get a return on your investment. Below are some basic guidelines for using a torque wrench.
- Do not use a torque wrench that does not come with a torque wrench calibration certificate.
- Torque wrenches should never be used to break fasteners loose.
- Perform whatever maintenance is stipulated by the manufacturer – this can be found in the owner’s manual.
- Pay attention to the scale – never set the torque values any higher or lower than those indicated by the scale.
- After use, lower the torque to its lowest setting, then clean it as necessary and store it in its case to prolong its pristine quality. (Digital torque wrench cases can often be purchased separately if needed).
- Do your best to avoid dropping your torque wrench – even analog wrenches can lose calibration if they are dropped.
- Calibration is tricky and is best handled by industry professionals as per the manufacturer’s recommendation. Never disassemble a torque wrench yourself.
- Be careful with used torque wrenches – be sure to test them before purchasing.
- Do not apply any extra torque. Use the recommended torque rating (or optimal torque) as a point of reference – going over this rating can cause the wrench itself to fail.
- Never use any sort of extension – including a breaker bar – to apply extra torque to a fitting. If you feel that you need additional torque, simply use a larger wrench.
Digital torque wrenches are worthy investments if you are able to treat them with regular product care and maintenance. While their built-in reading storage is a definite bonus, you should not feel pressured to purchase a digital wrench.
A regular torque wrench is perfectly capable of doing the job, provided you find one that is above average in quality. They’ve been around since the early 20th century, and they aren’t likely to go away any time soon. We hope the above has covered the common questions you may have had.