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Wire Rope Lubrication

By Mike Cork, Director, Research and Development

Two Functions
The lubricant in wire rope performs a dual function. One function is the lubrication of strands; the other is to inhibit corrosion which accelerates strand friction and decomposition.

Traditional Lubricants
Since the first half of this century, wire rope lubrication has been attempted with greases, petroleum, asphalt based materials , or oils. The heavier products such as petroleum, asphalt, or grease usually are applied with solvents or are heated until penetration is thorough. Data generated by research (1, 2) have cast light upon serious shortcomings of these approaches. First, heated materials rapidly cool when applied, casting doubt upon their ability to penetrate. Second, solvent-based products constantly change viscosity during application, and therefore have possible penetration problems of their own. Oils lack adequate wear and E.P. properties and offer poor corrosion protections unless continually applied. Even then, oils fare poorly under adverse conditions.

High Viscosity Materials
Recently, high pressure applicators have been developed to specifically address the problems of penetration with high viscosity materials. Asphalt based products, petroleum, and grease products, however, have an even more severe shortcoming in that in any dynamic situation, even if the rope is stationary, simply under tension (supporting dead weight) the compression of strands induced by weight, movement, or stress creates a migration pattern from the center of the rope outward. Temperature alone can increase the rate significantly, but even in warm climates this is only moderated, because migration is a response to characteristics of the viscous nature of materials used.

This event starves the center of its lubricant and thus allows fretting (friction between strands) and its accompanying corrosion to occur. Unfortunately, the phenomenon is hidden from the operator because lubricating materials remain on the outside diameter giving the appearance of a well saturated rope. In fact, close inspection , which is also hindered by the opacity of commonly used materials, will show the inner core corroding and wearing at an increasing rate(3). In severe cases one can see an almost hollow core due to center degeneration. This is a safety hazard and destroys a valuable piece of equipment.

Modern Lubricants
These shortcomings point up the characteristics that a modern wire rope lubricant should have. The material should provide anti-wear, extreme pressure and good corrosion protection. This implies a fluid material which can penetrate, rapidly re-heal during use, and allow periodic strand inspection. Since the material is thin, it will have to be periodically replenished during use, and herein lies a key.

Maintenance Intervals
Wire ropes need to be maintained and lubricated like any other piece of equipment. The object is to learn the maintenance time interval which is best determined by the duty cycle. Many drag lines must be lubricated continuously, some guy lines are inspected only once a month, if that often, but this should be a a function of environment amount of use and past experience. The new system of wire rope lubrication reveals how high viscosity materials not only failed, but perpetuated neglect by giving the appearance of being well covered and lubricated.

The new approach may require continuous, daily, or weekly re-lube cycles, but can, in some cases, increase wire rope life 50% to 150%.

The Solution
WRL-191S™ is designed to fill the need by industry for a dynamic lubricant with outstanding corrosion inhibiting ability in conjunction with excellent anti-wear and extreme pressure characteristics which exceed those of many greases and most petrolatum and asphalt formulations. This synthetic material has outstanding physical properties, being a functional lubricating film from -110 degrees F to 400 degrees F. It is non-solvent, essentially non-toxic, biodegradable and has good penetrating capabilities. WRL-191S™ can be applied by as a simple an apparatus as a gravity fed trickle system or by a continuous central lube system. Airless sprayer, compressed air sprayers, dipping and painting, have all been used to apply WRL-191S™. It is designed to give protection against hydrogen sulfide (H2S), mild mineral acids, carbon dioxide (CO2), saltwater and brackish environments, musky water, chlorine and similar adverse environments.

WRL-191S™ is virtually colorless when applied, allowing for easy inspection. Its formulated high strength film provides excellent anti-wear and extreme pressure characteristics to help stop fretting and wear, and is resistant to water wash-off. WRL-191S™ extremely thin film (less that .001 inch) resists dirt pickup, yet its film is exceedingly tenacious, affording protection even in the most dynamic situations.

Click here to purchase WRL191S synthetic oil in a size that's right for you.