What is wire rope?
Wires are the basic building blocks of a wire rope. They lay around a “centre” in a specified pattern in one or more layers to form a strand. The strands lay around a core to form a wire rope. The strands provide all the tensile strength of a fibre core rope and over 90% of the strength of a typical 6-strand wire rope with an independent wire rope core.
Characteristics like fatigue resistance and resistance to abrasion are directly affected by the design of strands. In most strands with two or more layers of wires, inner layers support outer layers in such a manner that all wires may slide and adjust freely when the rope bends.
As a general rule, a rope that has strands made up of a few large wires will be more abrasion resistant and less fatigue resistant than a rope of the same size made up of strands with many smaller wires. The basic strand constructions are illustrated below. In the example, each individual wire is arranged around a central wire to form a 7-wire strand. Six of these strands are formed around a central core to make a wire rope. The rope is specified as 6×7 (6/1) – i.e. six strands each of seven wires.
WIRE ROPE
WORKING
LOAD LIMITS
WIRE ROPE CORE
FIBRE CORE (FC)
Polypropylene or natural fibres are used as the core. Excellent flexibility and lubricant retention.
WIRE STRAND CORE (WSC)
A single strand is used as the core. Simple and cost-effective. Suitable for small diameter rope.
INDEPENDENT WIRE ROPE CORE (IWRC)
A small wire rope is used as the core. Excellent crush and distortion resistance with longer fatigue life and higher breaking strength.
MEASURING WIRE ROPE
Ropes are referred to by diameter size. The correct way to measure a wire rope is across the widest point, ‘The Crown”.
SAFETY INSTRUCTIONS
- Wire rope will fail if worn out, shock loaded, overloaded, misused, damaged, improperly maintained or abused
- Always inspect wire rope for wear, damage or abuse before use
- Never use a wire rope which is worn out, damaged, corroded or abused
- Never overload or shock load a wire rope
- Use the correct design factor for the application
- Inform yourself: Read and understand the machinery manufacturers handbook and guidance from the wire rope manufacturer
- Refer to applicable directives, regulations, standards and codes concerning inspection, examination and rope discard criteria
CARE AND MAINTENANCE
BREAKING IN
A wire rope may be looked upon as a machine composed of a large number of moving parts. As such it should be broken in as soon as it is installed, by loading it very lightly for a few cycles and then gradually increasing the load. This enables both wires and strands to ‘bed down’ into the working positions, with the load distributed as uniformly as possible. The use of ‘spinners’ or swivels should be avoided whenever possible. All ropes should be reeled onto winch drums as tightly and uniformly as possible during the initial installation.
INSPECTION
Wire rope is tough and durable, but nonetheless expendable and eventually reaches the end of its safe service life. Rope deterioration becomes noticeable through the presence of broken wires, surface wear, corrosion, wire or strand distortion due to mechanical abuse, or drastic reduction in diameter and lengthening of the lay. Also deterioration can be detected by the use of magnetic rope testing (MRT). Wire ropes should periodically be inspected for signs of deterioration.
LUBRICATION
Many industries use wire rope to carry out their work including cranes, mining, piling, drilling, draglines, shovels and civil. The wire rope in these applications often are exposed to harsh environmental conditions including extreme weather. The frequency of lubrication in the field is determined by the operating conditions of the rope e.g., high-speed heavy duty operation calls for more frequent lubrication, as do wet and/or corrosive conditions. For general purpose applications medium viscosity black oil is considered suitable. For corrosive conditions a high penetrating, water repellent rust-inhibiting oil should be used.
Ranger can help your wire rope last longer and operate safely by periodic scheduled lubrication. We use pressure lubricators to ensure lubricants penetrate right through to the core of the rope, not just the visible exterior. We offer Lanotec (which are lanolin based lubricants) or wire rope grease ensuring that the right lubricant is used for your rope, application and the installed environment.
WIRE ROPE INSPECTIONS
We help customers implement and manage comprehensive rope inspection programs. The reason for this is simple economics – the relatively low cost of highlighting potential problems before they have a detrimental effect on performance or safety, avoids the relatively high cost associated with downtime or incidents.
We have an in-depth understanding of all aspects of rope management including rope inspections and testing requirements in accordance with Australian and International Standards. We can undertake a thorough inspection of plant and rope systems as part of a complete inspection package to minimise the downtime of your equipment. Ranger can investigate and correct specific issues related to recurrent problems. Our highly trained technicians can efficiently carry out lifting equipment inspections, stringent testing and manage the administration of rope records.