FASTENERS & SEALING
PLANT BENEFITS FROM ADHESIVE THREAD LOCKING T
hreaded assemblies, subjected to load and vibrations, are often locked against self-loosening by either a mechanical locking device, an adhesive thread locker or a combination of both. The merit of this is easy to understand when the assembly is in a motor-driven machine where obvious vibration can cause an unlocked nut and bolt to gradually unwind. But what about a completely static object such as a solar panel? Surely that’s a good example of a bolt- down-and-forget application? The short answer is no, it is not. Panels are exposed to a variety of weather conditions and wind will cause enough vibration for the panel mounting bolts to loosen over time. Additionally, the panels are subject to thermal cycling, they are directly exposed to sunshine, shade and night-time temperatures as well as seasonal variations. The metal
bolt failure. The solution was a specific adhesive thread locker that could be applied to already- assembled nuts and bolts. The firm chose to lock its threaded
bolts therefore expand and contract with the changes in temperature, leading to an additional loss of torque. A Japanese solar power plant decided to take action to prevent this happening when it assessed the loss of revenue for the time that panels were out of commission and the increased maintenance costs involved in rectifying
assemblies with an engineering adhesive rather than a mechanical device, such as a spring washer, because it proved the most efficient. The product the plant chose was Loctite 290, a liquid medium/high- strength thread locker for locking and sealing threaded fasteners. Because of its low viscosity and capillary action, the adhesive actively creeps in between the threaded surfaces. This meant engineers could apply it to the nuts and bolts in situ, saving maintenance time in the process and creating assemblies that were both long lasting and corrosion-resistant. l
For more information visit
www.henkel.com
LOW-ODOUR, LIGHT CURABLE ADHESIVE A
dhesives supplier Intertronics recently launched Born2Bond Light Lock, a low-odour, low bloom,
dual-curing cyanoacrylate adhesive (CA). Designed for a wide range of bonding applications that require fast fixture, coating or surface cure, Light Lock’s dual- cure formulation includes both instant (surface) cure and light cure. It is available in high viscosity and gel formulations
for bonding, repair, coating or infilling applications. Light Lock offers typical instant CA adhesive bonding (typically by exposure to surface moisture) for fast interfacial curing, while its UV and visible light reactivity allows rapid curing of exposed fillets or areas, as well as through transparent parts. This means it can solve the typical CA bonding challenge of curing outside of the bond line. Without light exposure, Light
Lock’s fixture time is around 60 seconds, while with low power visible or long wave UV light it is curable in less than 5 seconds. UV wavelength is not critical – the useful range is from 365nm to 430nm and low cost LED-based curing technology is effective. “Cyanoacrylate adhesives are strong and fast products
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www.engineerlive.com
for interfacial bonds,” says Ben Swanson at Intertronics. “However, they don’t tend to cure quite so well if not between two surfaces. The addition of light curing of any exposed adhesive brings process improvements and decreases the risk of contamination. Light Lock is a simple solution for exposed bond lines, while offering all the benefits of Cas – it is single part, fast curing and adheres to multiple surfaces.
“It does not offer the shortcomings of traditional CAs, like blooming, an aesthetically undesirable residue on the surface of a part – a side effect of CA’s volatility and fast cure,” Swanson adds. “Manufacturers can therefore realise the benefits of both CA and UV technology in one easy to use adhesive product.” l
For more information visit
www.intertronics.co.uk
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