Wire ropes are hard-working components in many different applications, from mines to lifts, ports, construction sites and drainage systems. Correct lubrication of wire ropes is “absolutely critical” because wire ropes are more than just cables – they are intricate machines composed of interdependent parts in constant motion, says Ron Byrnes, senior technical sales representative and wire rope specialist at Lubrication Engineers (LE) South Africa.
“Wear takes place, not only between the wires, but also the strands, as a result of the linear movement within the rope.” Supplied by Lubrication Engineers (LE) South Africa
With over 30 years of experience working with wire ropes, including working directly on major southern African mines and for a wire rope manufacturer, Byrnes explains, “Wear takes place, not only between the wires, but also the strands, as a result of the linear movement within the rope.”
Without lubrication, the insides of a wire rope will corrode. Byrnes says that corrosion does not automatically equate to rust. “It is also the loss in steel or steel area within the rope as the rope components scuff and fret against each other,” he explains. Correct lubrication can significantly reduce this wear, extending the safe and useful service life of the rope.
“Rust corrosion is equally important, but It is more likely to see internal wear in a rope which is very difficult to contain; without lubricant, in fact, impossible,” adds Byrnes.
Improving lubrication practices
At many sites and in various applications, lubrication of wire ropes can be quite “hit or miss” says Byrnes, as operational teams just keep an eye on their ropes and lubricate them as and how they think is needed, and they are only able to really assess the state of a rope and the amount of lubrication required when running a non-destructive electromechanical test.
However, Byrnes advocates for an “application theory approach to the lubrication of wire ropes”. It includes two key aspects of understanding the rope: first, how it works, what function it plays in a particular application and how it moves; and second, how the lubricant works with that movement within the rope to diminish the effects of wear and corrosion.
The South African context
In South Africa, there are both locally manufactured and imported wire ropes in operation, and these have different construction and rope designs. The lubricant is applied to a rope at the time of manufacturing also differs. In South Africa, it’s usually a bitumen-based lubricant. This is a coating grease which must be heated before it can be applied because it is very hard and thick. When it is heated, it can be poured onto a rope through a funnel.
In terms of how this affects the approach to lubrication once a wire rope is in use, Byrnes says that it is important to have a lubricant that can work successfully for the rope, regardless of the type of lubricant applied at the point of rope manufacture. “We can’t obviously change what manufacturers do, but what we are looking for is a perfect fit: a match of our product offering that best complements and is also compatible with what is done at the time of rope manufacture,” he says.
He recommends LE’s Wirelife® Monolec® Penetrating Lubricant 2001, that has a Timken OK Load rating of 27.2kg and diluent additive, to enhance the penetration of the lubricant into the rope interstices, for imported high performance compacted wire rope as well as LE’s Wirelife® Almasol® Coating Grease 452 that has an NGLI 00 grade, for round, non-spin and 6-stranded triangular ropes. This provides a lubricant fluid enough to be able to be massaged between the outer strands and into the core of the rope using a Viper Rope Lubricator.
A Viper Rope Lubricator is a collar with seals which is strapped down and held in place so a rope can move through it. A wire rope cleaner can be attached to the front of the system, which spins against the rope as it moves through it, removing old lubricant and cleaning it. Then fresh lubricant is applied as it moves through the Viper Rope Lubricator.
Even on ropes which have previously had a bitumen-based lubricant applied, Byrnes says that the Wirelife® Almasol® Coating Grease 452 does not fling off.
Byrnes also says that in sub-zero conditions, bitumen-based lubricants become hard and brittle and fling off the rope, causing damage. However, Wirelife® Almasol® Coating Grease 452 functions effectively in a wide range of temperatures, from -20oC to over 120oC.
Environmental benefits
Environmental impact is another critical aspect of rope lubrication. Bitumen-based lubricants, when exposed to fire, release toxic fumes which pose significant health risks. In contrast, LE’s products are designed to meet stringent safety and environmental standards, with high flash points and reduced emission of harmful substances during combustion.
Byrnes emphasises the importance of aligning lubrication practices with the Mine Health and Safety Act and OSHA regulations to ensure worker safety and environmental compliance.
The maintenance of wire ropes is a critical aspect of operational safety and efficiency in many industries and applications. Adopting a systematic and scientifically informed approach to lubrication can have a positive effect on the performance and longevity of these essential components, as well as safety and environmental impact.
Source: Supplied by Lubrication Engineers (LE) South Africa