Wire rope is a flexible steel cord that is extremely strong. Typical uses for wire rope are: hoisting, towing, and anchoring heavy loads. The core is the foundation of a wire rope. The three most commonly used core designations are: fiber core (FC), independent wire rope core (IWRC), and wire strand core (WSC).
Q.What are the factors affecting the selection of wire rope?
1. Strength-resistance to breaking The wire rope should be strong enough to handle the maximum potential load including safety factors
2. Resistance to bending fatigue Fatigue is caused by repeatedly bending rope around drums, sheaves, etc. A wire rope with strands made up of many small wires will be more resistant to fatigue, but less resistant to abrasion
3. Resistance to vibrational fatigue Energy is absorbed at the end fittings or at the tangent point where the rope contacts the sheave
4. Resistance to abrasion Abrasion occurs when a rope is dragged over the ground or other surfaces. A wire rope with strands made of fewer, larger wires will be more resistant to abrasion, but less resistant to fatigue
5. Resistance to crushing During use, a wire rope may encounter crushing forces or be struck against hard objects. This can cause the rope to become flattened or distorted, resulting in premature breakage. Wire rope must have sufficient lateral stability to withstand the crushing pressures it may encounter. Regular lay ropes have greater lateral stability than Lang’s lay, and six strand wire ropes have greater lateral stability than eight strand
6. Reserve strength Combined strength of all the wires contained within the strands
Q.What are the rope lay options?
The finished rope has either a right or left-hand lay, which refers to the direction in which the strands were wrapped around the core. Regular lay means the individual wires were wrapped around the centers in one direction and the strands were wrapped around the core in the opposite direction. Lang’s lay means the wires were wrapped around the centers in one direction and the strands were wrapped around the core in the same direction. The length of lay is measured as the distance in inches for one strand to go completely around the rope one time.
Q.What are the differences among Bright, Galvanized and Stainless Steel Wire ropes?
Bright wire rope is fabricated from wires that are not coated.
Rotation Resistant Bright wire rope is designed to resist the tendency to spin or rotate under load. To achieve the resistance against the spin and rotation, all wire ropes are composed of at least two layers of strands. In general, more layers a rotation resistant wire rope has, more resistance it will boast.
Galvanized wire rope tests at approximately the same pulling strength as Bright, however, it is zinc coated for corrosion resistance. In mild environments, it’s an economical alternative to stainless steel.
Stainless Steel wire rope is made up of corrosion resistant steel wires and is, therefore, the highest quality wire rope available. While it tests at approximately the same pulling strength as Bright or Galvanized, it lasts the longest under harsh conditions such as salt water and another acidic environment.
Q.What are the different wire rope constructions?
Q.What are the options for wire rope coating?
While there are numerous options for coating of wire rope, the most common are Zinc and PVC (Polyvinyl chloride). Some of the reasons for selecting coating are to protect the cable from the environment or unwanted materials, to help reduce friction and abrasion, or simply for aesthetic reasons.
Q. What are the types of Wire Rope failure?
Q.How to order a rope?
HOW TO ORDER A ROPE
Nominal diameter and tolerance
Construction / Class / Brand name
Finish (galvanized or un-galvanized)
Minimum Breaking load requirement
Core – Fibre / IWRC / WSC
Lay – eg. Right-hand regular lay
Packing – wooden reel/ steel reel / Coils.
Particulars of fittings
Performed / Non-performed
Exact length per reel/coil etc (special length tolerance, if any)
Note:- It is always important to state the application of the rope other than the above points to ensure the correct rope for your purpose.
Q. What are the recommended Do's and Don'ts while handling a wire rope?
RECOMMENDED DO’S & DONT’S
Lubricate ropes with good quality acid free and moisture free lubricant.
Regularly inspect the sheaves, rollers or pulleys – the life of a rope largely depends on their contheir conditions.
Inspect ropes and fittings / terminations periodically.
Do not allow ropes in store to deteriorate.
Do not mishandle ropes when uncoiling or unreeling & allow kinks to form.
Do not use Langs lay with a swivel.
Do not use a rope with too large groove diameter on drums and pulleys.
Do not cut a rope without sufficiently flexible for the size of drum or pulley.
Do not load the rope beyond its safe working load Reduction of safety factor may jeopardize not only rope, but also equipment, job and men.
Note:- Rememmber – Care in handling, installation, and careful inspection gives more life and enormous dividends.