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A guide to wire rope lubricants

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Cable or wire rope is an integral part of many machines and structures, including cranes, lifts, shovels, drilling rigs, and suspension bridges. These are used in industries such as marine, construction and mining, which involve intense operating loads and challenging environmental conditions.

Consisting of continuous wire strands, they are wound around a central core, made of steel, rope or sometimes plastics. Regardless of the type and size required, all wire ropes will see better high-level performance and durability when properly maintained.

Wire rope lubrication

Wire ropes are made using cost effective high carbon steel to guarantee robustness and flexibility. When the rope has a fibre core, it will be lubricated during manufacturing with a mineral oil or a petrolatum type lubricant, absorbing the lubricant whilst in service.

Does wire rope need to be lubricated?

Once the cable is in service, relubrication is needed as periods of loading, bending and stretching will have caused loss of the original lubricant. This is because the fibre core cables absorb moisture, drying out and evaporating over time due to heat buildup.

Thus, comprehensive lubrication provides machinery and equipment with an extended service life, offering structural integrity and greater protection against contamination, rust corrosion and wear and tear. Lubricants are specifically formulated to ensure compatibility with equipment including chains, wire ropes, and gear boxes.

What is the best lubricant for wire ropes?

Dirty and contaminated cables should be cleansed of hardened lubricant residue and other contaminants which may have built up. This should be done with a wire brush, and if necessary also using a petroleum solvent, steam cleaner or compressed air. The wire rope should then be dried and relubricated straight away to prevent any rusting. Lubricants can be applied as liquids, sprays or gels, and are engineered to offer simple and safe application. This lowers operating and maintenance costs and extends active service life for wire ropes.

Wire rope lubricants offer two main functions: friction reduction as the individual wires come into contact and corrosion protection in the core, internal and external wires. Often, ropes with fibre cores are easier to lubricate than those made from steel materials. It is therefore important to carefully consider methods of relubrication when picking rope for an application.

What type of lubricant is suitable for wire?

There are typically two types of wire rope lubricants: namely, penetrating and coating. Penetrating lubricants have a petroleum solvent which introduces the lubricant into the core of the wire rope core before evaporating. This leaves behind a thick lubricating film which protects and lubricates each strand; whereas coating lubricants are used for sealing the cable exterior from moisture and for reducing corrosion from external friction.
A ‘combination’ approach uses penetrating lubricant to saturate the core, followed by a coating to seal and protect the outer surface. Wire rope lubricants include petrolatum, asphaltic, grease and petroleum oils or can be vegetable oil-based. With the correct additives, petrolatum compounds are translucent and offer effective corrosion and water resistance. Whilst they can drip off under heat they maintain their consistency well in colder temperatures.

Different types of common grease thickeners are used in wire rope lubrication: sodium, lithium, and aluminium complex soaps. Petroleum and vegetable oils are most effective, due to their excellent wear and rust resistance and fluid properties which help to wash the rope of abrasive external contaminants.

What is the reason for greasing wire ropes?

Different environmental factors can influence cable life cycle and performance. Cables can be adversely affected by improper storage and winding, worn sheaves, and splicing practices. Wear can be accelerated by high stress, shocks and heavy loads, or fast acceleration or deceleration. Durability can be compromised by corrosion due to metal loss and pitting. In service, corrosion and rust are aggravated by fumes, acids, gases, and humidity and accelerated by high temperatures. Lubricants can therefore reduce any corrosive activity.

During normal operation, friction between individual strands inside the rope can create internal abrasive wear both on the inside and outside of wire ropes. The cable exterior accumulates dirt and contaminants from sheaves and drums, and this erodes the outer wires and adjacent strands. The effect of such abrasive wear is to reduce rope diameter and cause core failure as well as internal wire breakage. Penetrating wire rope lubricants are effective at reducing internal rope abrasive wear and also in removing external surfaces of contaminants and dirt. When shutting a machine down for a lengthy period, cables should be cleaned, lubricated and stored away properly. For further help and support on your wire rope lubricant needs, reach out to us today.

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