Henkel recently revealed that the use of its LOCTITE 270 adhesive rescued an Australian operation when the mine discovered an issue with the equipment frame of its jaw crusher.
In a new case study from the company, Henkel said the mine had used M36 anchor bolts for the frame, locked by spring washers that did not secure the bolts as it continuously vibrated and faced high shear forces.
As a result, the threaded assembly failed and self-loosened, then broke off. The concrete fittings also collapsed.
“Spring washers – also known as lock or helical spring washers – are one of the most popular mechanical devices for securing threaded fasteners against self-loosening,” the company said.
“The washer is squashed flat when the nut is tightened against the mounting surface so that its sharp edges dig in to prevent the threaded fastener unwinding.”
In the case of the Australia mine, which was not named, the issue was made worse by the bolts’ size; the bigger the bolt, the bigger the gap between threads, leading to more vibrational impact on the assembly. With typical assemblies, conversely, there is a 15% efficient metal-to-metal contact between the threads, and everything else is empty space to enable plenty of side-to-side movement for the bolt.
The mine’s realisation of the problem resulted in a decision to change over to adhesive thread locking with LOCTITE 270 to fill the gaps and prevent movement of the bolt in the nut.
“Secured this way, the assembly is completely vibration-proof but can still be easily dismantled with hand tools for repair and maintenance,” Henkel noted, adding that the simple adjustment has not only helped productivity but also played a role in safer mining for the workers at the operation.