Advice for Lubricating Wire Ropes

Noria Corporation

"We are a mechanized cable supplier, and we apply grease on the wire ropes by manually brushing grease on a set number of wire ropes (say 10 pieces) at a time and then insert the lubed wire rope into the conduit. Is there a testing method for a single finished cable assembly? How much grease should be applied? If there is a better testing method, do you know any testing labs that are qualified to do this testing?"

Cable and wire ropes are lubricated for a variety of different reasons. One reason is to reduce the rubbing friction of the wires in the rope as they move relative to each other. These wires are wrapped around a core of either cable or rope. The rope flexes as it is pulled around pulleys or wrapped onto spools, and the wire moves within the braid of the rope. The movement of these wires causes friction and can wear down the metal. The lubricant is there to help in this case. By reducing friction, you can lessen the heat generated and possibly the amount of wear caused by the wires rubbing against each other, thus extending the life of the wire rope.

Another reason wire ropes are lubricated is to protect them against corrosion. Since these ropes are subjected to direct atmospheric contact in most applications, it is important to protect the metal wires from contaminants such as water, which can form rust and weaken the integrity of the wire rope.  

Greases and oils perform these lubricating tasks with different results. Certain types of oils penetrate the wire and can reduce friction very well. These compounds not only provide lubrication as they penetrate to the core of the rope, but they also leave behind films that help protect against corrosion. Greases coat the outside of the wires and protect them very well, but their penetrating properties are generally less than that of oil.

The amount of grease or oil needed to lubricate wire ropes is dependent upon their size, and the frequency of relubrication will depend on such factors as loading, operating environment, contaminants, etc. The testing methods for lubricants used on wire ropes are similar to those for other applications. You want to know the grease’s bleed characteristics as well as any extreme-pressure test results. How well the lubricant protects against rust in harsh environments is another important factor in choosing a quality wire rope lubricant.

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