Lube-Tech PUBLISHED BY LUBE: THE EUROPEAN LUBRICANTS INDUSTRY MAGAZINE
are expected to last for an extended period of time. The other category is the lubricants that are applied to wire ropes during service. There are two types of this second category, penetrating lubricants and coating lubricant. Those could be low viscosity lubricating penetrants or high viscosity oils or low consistency grade greases. As with most lubricants, wire rope lubricants can serve several purposes. As the name would suggest, they are first lubricants. Frequently, they are secondarily designed to coat and protect the rope from corrosion. Lack of lubrication would result in reduced longevity for wire ropes (Figure 2).
. Figure 2. Without proper lubrication wire ropes degrade and lose longevity
Category 1 – Rope Manufacturing Lubricants: Wire rods are made from hot rolled, high carbon steel billets that are drawn to the desired diameter ranging from 5.5 mm to 8 mm. The rods are then heat treated (patented) to a specified micro structure. A second drawing may reduce this to smaller diameters adding mechanical stability and obtaining the desired diameter. During each of these processes suitable lubricants may be used because of the amount force applied to the wires. In the process of “stranding” the wire strands are made by combing a number of
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wires to be used on the core. Finally, in the process of “closing,” the sets of strands are laid in layers over the core completing the wire rope. The lubricant used at this stage is especially important in the longevity of the wire rope. Figure 3 illustrates the process starting from the wire rods and ending with wire ropes. The chemistry of the steel and its carbon content along with the heat treating process used in drawing the wire make for a variety of tensile strength, fatigue and wear resistance in the final product2
Category 2 – In-Service Wire Rope Lubricants: It was previously explained that there are two types of in-service wire rope lubricants that are commonly used, coating lubricants and penetrating lubricants. Formulation techniques used in an attempt to prepare hybrid products that provide some level of penetration while at the same time leave a coating.
Penetrating wire rope lubricants are typically low viscosity, fluid like products. These products range in consistency from low viscosity and solvent-like up to very sticky and viscous like corn syrup. Obviously, the level of penetration will be deeper and more rapid the lower the viscosity of the product.
Coating wire rope lubricants often contain thickeners, such as resins, asphaltic hydrocarbons, clay, grease soap, and waxes that once applied do not easily penetrate the rope, but instead leave a gel-to-almost-solid coating on the exterior of the rope. While this type lubricant may not as easily penetrate into the rope, it provides stronger protection against ingress of abrasive contamination and rusting of the rope by providing a stronger external barrier between the rope and the service environment.
Figure 3. Wire rope manufacturing process2
Continued on page 34 LUBE MAGAZINE NO.130 DECEMBER 2015 31
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