Fasteners & Sealing
4 Nobody wants a threaded fastener to fail. Paul Stevens reports on some of the latest developments for ensuring that threaded fasteners are tightened correctly and do not lose their tension over time.
Torque management ensures the security of threaded fasteners
W
hile non-threaded fasteners are gaining in popularity for many applications, threaded fasteners are often a better option where close control is required over
the joint characteristics. Consumer products from laptop computers to domestic washing machines feature threaded fasteners, as do high-value goods such as cars. On a larger scale, threaded fasteners are also used in, for example, wind turbine blades and flanged joints for pipelines. Depending on the application, failure of the joint might result in inconvenience for the user, warranty claims or incidents with catastrophic consequences for human life or the environment. To ensure the security of bolted joints, engineers today rely on both equipment that monitors the torque applied to the fastener, and torque-indicating fasteners that can show whether or not the fastener tension remains correct. Assuming that joints have been designed correctly, torque management can help to ensure that joints perform as intended over the lifetime of the application.
Torque wrenches apply a torque to a fastener in order to induce a tensile load that clamps the components together - and keeps them clamped under all anticipated service conditions, which might include temperature fluctuations, vibrations and static loads. Regular calibration to International Standards is vital to ensure torque equipment is operating within defined tolerances. Torqueleader, a manufacturer of torque tools, reports that its United Kingdom Accreditation Service (UKAS) laboratory is capable of recalibrating most hand torque tools, analysers and transducers in accordance with the standards. Furthermore, the UKAS laboratory can calibrate tools from many other manufacturers besides Torqueleader.
Operator comfort
Crane Electronics offers some of the most advanced measurement technology with its latest product, the IQWrench Opta, which maximises the comfort of the operator. Feedback on the fastening process is important if the operator is to make each joint correctly.
Fig. 1. Rotabolt fasteners feature a Rotacap on the head that locks in position at the correct design tension but spins freely if tension is lost.
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