Henkel’s LOCTITE® 270 adhesive thread locking has come to the rescue of a mining operation in Australia that was facing a potential collapse of the jaw crusher equipment frame.
According to Henkel, the failure of a threaded assembly through self-loosening not only risks lost production but also worker safety. This was the case at the Australia mine site.
The M36 anchor bolts in question had been locked by spring washers that could not rise to the challenge of securing bolts on a piece of equipment subject to continuous vibration and high shear forces, according to Henkel. This resulted in the loosening – and, ultimately, breaking off – of anchor bolts and the collapse of concrete footings.
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, Henkel says. 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 practice, a spring washer may delay the length of time it takes for the bolt to loosen, but it will not permanently prevent it, according to Henkel. “The main reason is that the split washer does not solve the gapping issue, the free space remaining between the threads of the nut and the bolt,” it said.
On a typical threaded assembly there is just 15% efficient metal-to-metal contact between the threads. Everything else is empty space that enables plenty of side-to-side movement for the bolt. Additionally, being metal itself, a spring washer can cause damage to contact faces and corrode in place.
For the Australia mining operation, this problem was exacerbated by the size of the bolts. The bigger the bolts, the bigger the gap between threads, which leads to more vibrational impact on the assembly. This realisation resulted in the company changing to adhesive thread locking with LOCTITE 270, according to Henkel.
This is a high strength formulation that fills all gaps between the thread and prevents any movement of the bolt within the nut, according to Henkel.
“Secured this way, the assembly is completely vibration-proof but can still be easily dismantled with hand tools for repair and maintenance,” it said. “Additionally, the liquid thread locker seals the threads against humidity and dust, preventing corrosion and surface erosion.”
This simple adjustment to working practice has not only underpinned productivity but contributed to a safer working environment at the operation, Henkel says.
One 50 ml bottle of liquid thread locker is sufficient to secure around 850 M10 bolts but, unlike spring washers, can be used on any bolt size, according to the company.