Lubrication and corrosion protection is necessary for the proper maintenance of any machine. As a machine, an operating wire rope must also have a lubrication maintenance programme to ensure it is functioning properly. ONWO wire rope dressing is designed to cater for a multitude of applications and working conditions. Applied during manufacturing, lubricants are selected on the basis of rope service requirements. For example, ropes for heavy-duty stripping shovels have a relatively short service life and need a lubricant suitable for the abrasive conditions under which the wire ropes operate.

Lubrication during manufacturing

During the manufacture of wire rope, the lubricant can be applied to individual wires during the stranding operation. The lubricant amount is then regulated on the finished strand by a special wiping process which determines the lubricant content of the strand. The quality of the lubricant in a wire rope is just as important as the quality of other rope components (wire and core). When a wire rope is in operation, each wire is in contact (over its entire length) with other wires, sheaves and drums. The strands also move with respect to each other and with the core. The need for a lasting and tenacious lubricating film between all of these components is necessary to minimise wear between the wires, strands and the fibre core. It is important to use penetrating type of rope dressing such as ONWO Ropesafe, which will become absorbed by the fibre rope core and thus provide constant lubrication and protection. In fact, the core's other important functions are to provide support to the strands and contribute elasticity to the rope.

During core manufacturing, lubricant penetrates the core, but eventually the lubricant breaks down. Since the factory-applied lubricant is gradually dispersed during the operating life of the hoist rope, and understanding that the fibre core is not a lubricant reservoir, elevator hoist ropes need to be field lubricated during their service life.

Field lubrication

Field lubrication is necessary to:

• Minimise wear between ropes and sheaves.
• Reduce friction between the wires.
• Minimise both internal and external corrosion due to atmospheric and/or operating conditions.
• Help reduce bending fatigue by allowing movement between the wires and strands.
• Provide protection in dusty and abrasive environments.
• Enable easy application with brush, swab or by auto applicator.
• Facilitate easy inspection of wire ropes by keeping them free of compacted dust and dirt.
• Ensure no contamination of the surrounding work area from lubricant is dripping or flung off.

A lubricant meeting these requirements is ONWO Ropesafe 00 Dressing, which penetrates the wire rope providing internal lubrication and protection and forms a lasting, thin lubrication film on the outer surface of the wire ropes, which does not accumulate dust and dirt.

ONWO solutions

The role of the wire rope lubricant is to reduce scuffing wear on the outer strands and sheaves, lubricate the rubbing between strands and importantly to protect against corrosion. Wires move relative to each other as the wire rope passes around sheaves and drums. Rubbing occurs between the wires as they move; the smaller the sheave diameter and multiple sheaves mean the greater the wire adjusting movement and the more rapid that rubbing and fatigue wear may occur. Every wire through the length of the rope must be free to move and adjust. Unless it is correctly lubricated to the core, this essential movement cannot take place. Fatigue life of ropes can also be greatly extended by proper lubrication, when the wires can move freely to equalise stress distribution caused by sheaves or drums. Finally, lubricant must reach fibre cores or they will absorb moisture and encourage corrosion from the centre.

Total maintenance solution

Raj Petro recommends the use of ONWO RopeSafe 00 grease. This NLGI 00 semi-fluid grease is a tacky, water resistant, semi-fluid lubricant that penetrates all wire rope strands ensuring smooth operation and extended cable life. The covering power per kg is far greater when compared to conventional grease and bitumen compounds. The use of Ropesafe 00 will reduce lubricant sling off which can occur when using conventional lubricants. This is particularly important when lubricating wire ropes used in proximity to marine environments. Ropesafe 00 also protects against corrosion attack in salt water environments or where long time immersion in water is expected.