Engineering adhesives from Henkel are helping to ensure safety and keep vibration to a minimum in some of the most demanding applications, where security of bond is essential
Over the years, adhesive technology has evolved greatly, and designers today now have the option of specifying a solution which will meet the demands of even the most rigorous of applications. In fact adhesives are now being used across all industry sectors, and on some occasions are used in conjunction with mechanical fasteners to suit the demands required.
In one rather unusual application, adhesives from Henkel have been selected for use on Silver Star, a 1620m long 73m high hypercoaster capable of speeds up to 130km/h, with performance equalling the acceleration and G-force of a Formula One car.
With the rollercoaster, the speed and passenger load are constantly calculated to apply just the right amount of magnetic braking, but vibration needs to be kept to a minimum. The passenger safety bars are checked every day and annually stripped down for detailed inspection. During re-assembly the maintenance engineers use Loctite 243 to threadlock the bolts that connect the ratchet components to the main bar. Threadlocking adhesives prevent self-loosening and secure any threaded fastener against vibration or shock loads. They also fill the gaps between mating threads and eliminate fretting corrosion.
Like the safety bars, the guide wheels which are crucial to keeping the train locked to the track from above, below and from the side, are also checked daily and subject to thorough inspection and re-assembly annually. During this process the steel ball-bearing cages must be completely removed from the aluminium wheels.
Here, engineers warm the wheels to 70°C which allows them to push out the steel ball bearing cage. They then clean all surfaces with Loctite 7063, a general purpose cleaner and degreaser that leaves no residue and is suitable for use prior to adhesive bonding and sealing applications. Loctite 638 is then applied to re-fix the cage. Formulated to provide the best resistance to dynamic, axial and radial loads, this high strength retaining compound achieves maximum load transmission capability, uniform stress distribution and also eliminates fretting corrosion.
The bolts that secure the ball-bearing cage casings and those that fasten the wheels to the train are then threadlocked with Loctite 243.
Supporting bolt connections
In a very different application, Loctite anaerobic adhesives have been chosen to support critical bolt connections on combine harvesters where they are exposed to acute and lasting vibration.
One of the most severely stressed components in New Holland’s high-performance 600 horsepower combine harvesters is the twin rotor thresher. To secure its bolts, the company uses Loctite 270 threadlocker.
As the bolts are hard to access to re-tighten on the finished vehicle, this application ensures they will withstand the extreme vibration caused by the threshing action during harvesting, a process that can span many weeks.
A central gear drives the two 2.5m long thresher rotors and here Loctite 638 anaerobic high strength adhesive is used when assembling the shaft hub joints. With the help of an activator, the adhesive cures rapidly and securely fixes the central gear.
Added to this, Loctite 542 is used in the assembly of the hydraulic system to prevent any leaks.
However, the anaerobic products have also been chosen for their ability to optimise the assembly processes. In one example, Loctite 515 flange sealant is used during pre-assembly for the efficient and cost-effective protection of the axle bearings against moisture from the washing process.
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