Fasteners & Sealing
can be used indefinitely (Fig. 2). Accu-Load can also supply handheld mechanical or digital readout systems for remote monitoring. The technology is widely used on complex flange arrangements and critical environments on processing plants where even and accurate tensioning is required in the presence of vibration or thermal shock loads.
Combat fatigue
Another indicating fastener, the Ecostud from Arnold Wragg, is said to combat fastener fatigue failures and leaking joints by combining a quality fastener and an accurate tension controller within a single integral unit. The bolt allows easy identification of fasteners that are losing tension and enables them to be retensioned before a leak starts. As Ecostuds are a direct replacement for standard threaded fasteners, only the original size, material and required preload needs to be
specified either for a new installation or a retrofit. The Ecostud is fitted with a stainless-steel rotor that is
locked when the stud is tight, but free to spin when the stud begins to lose load. A fingertip test on the rotor establishes whether the joint is still tight (Fig. 3).
High-vibration loading
To illustrate the savings in maintenance times offered by products such as the Ecostud, consider a wind turbine. Each blade will typically have 60 retaining studs, equating to 180 studs per turbine - and there will be many other critical fasteners in addition to those retaining the blades. The blade studs are subject to high-vibration loading and must have the correct tension to avoid fatigue failure. Checking the Ecostud takes a fraction of the time required with the traditional method of engaging the torque wrench on each stud. Finally, for mobile engineers, Norbar Torque Tools has
developed a torque conversion calculator app available as a free download for iPhone and Android handsets. Similar to the online calculator on the company’s website, the app offers instant conversion across SI, metric and imperial units. Threaded fastening is a mature technology, but
developments continue in the ways that fasteners are installed and tightened correctly. For applications where operational conditions could lead
to the joint relaxing, engineers today have a wider choice of means by which fasteners can be checked for tightness both quickly and easily.
Torque wrenches and controllers for engine assembly
For 10 years the Ford engine plant at Dagenham has relied extensively on torque control products from Crane Electronics. In the latest stage of this on-going relationship, Ford has invested in new TMAC Opta tool controllers for use in conjunction with its existing Crane Wrenchmaster heavy- duty torque wrenches. This combination is used on Ford’s Puma Line, which produces diesel engines for Ford Transits, Jaguar (X-type) and the Land Rover Defender. The TMAC Opta replaced an original TMAC II torque controller. Together the controller and wrench have to process data
and withstand the harsh environment of a production line assembling up to 1500 diesel engines per day - representing some 6000 critical fastening operations on critical fuel injector assemblies. TMAC Opta tool monitoring and control units have
Fig. 3. Ecostud fasteners feature an integral tension gauge that directly measures the strain in the fastener to an accuracy of ±5 per cent.
Bekaert Broadbent CarlStahl Congatech
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a number of features that help to ensure maintenance requirements are minimised and production is not interrupted. These include robust and highly intuitive software, isolation of internal circuits and a rugged housing. l
Euromold Hilliard Lemo Minitab
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