Wire Rope Damage Causes and Prevention

[MikePhua]

Introduction
Wire ropes are vital components in heavy equipment, cranes, and lifting operations, designed to bear significant loads and operate under challenging conditions. Despite being engineered for strength and durability, wire ropes can suffer premature damage and failure. Understanding the main causes of wire rope damage is crucial to enhance safety, prevent downtime, and reduce replacement costs.
Common Causes of Wire Rope Damage

• Overloading: Using the wire rope beyond its rated safe working load causes strand breakage, permanent deformations, and internal damage. Shock loading or sudden jerks accelerate wear and reduce service life.
  
• Abrasion: Friction between the rope and sheaves, drums, or rough surfaces wears down the outer wires. Improperly sized or worn sheaves with sharp or tight grooves increase abrasion. Contact with external objects or contaminants also contributes.
  
• Corrosion: Exposure to moisture, chemicals, and free radicals causes rusting and degradation of wire strands, weakening tensile strength and making the rope brittle.
  
• Improper Handling and Installation: Incorrect reeving, sudden pulls, kinking, twisting, or bending create internal stresses that weaken the rope. Poor splicing or storage increases risk of damage.
  
• Fatigue: Repeated bending over pulleys and sheaves induces microscopic fractures in strands. Over time these fractures propagate, leading to visible broken wires and ultimately, rope failure.
  
• Rope Biting/Slippage: When wires overlap improperly on winding drums or due to poor drum and crown wheel design, rope biting occurs, causing internal damage and accelerated wear of the galvanized protective layer.
  

Inspection and Maintenance
Regular inspection is essential to catch early signs of damage:

• Visual Checks: Look for broken wires, corrosion spots, cracking, abrasions, and deformation.
  
• Diameter Measurement: Loss of rope diameter greater than 6% often indicates internal damage needing rope replacement.
  
• Lubrication: Proper lubrication reduces internal friction and corrosion. Use manufacturer-recommended lubricants and apply evenly.
  
• Storage: Store wire ropes in dry, well-ventilated environments away from corrosive elements. Protect from direct sunlight and moisture.
  
• Handling: Use trained personnel for installation. Avoid kinks, twists, and sudden shocks during reeving and operation.
  

Preventive Measures

• Choose the correct wire rope type balancing abrasion and fatigue resistance based on application.
  
• Ensure sheaves and drums are properly sized, grooved, aligned, and maintained to reduce wear.
  
• Use axial moving crown wheels or other engineering controls to minimize rope biting especially in double-layer winding drums.
  
• Adhere strictly to rated load limits including dynamic load factors.
  
• Employ load monitoring devices when possible.
  
• Implement routine maintenance schedules including scheduled lubrication and inspections.
  
• Document and log all wire rope inspections and maintenance actions.
  

Case Example
A mining company experienced premature failure of a recently replaced wire rope on a hoist. Investigation revealed improper installation with excessive fleet angle and a worn sheave causing variable stress and abrasion. After switching to correct sheaves, improving installation training, and instituting a lubrication program, rope life extended substantially, reducing downtime and replacement costs.
Terminology

• Strand: A group of wires twisted together that form part of the wire rope.
  
• Fleet Angle: The angle between the wire rope and the sheave; excessive fleet angle causes increased wear.
  
• Sheave: A pulley with a grooved wheel designed to guide and support wire rope.
  
• Ropecore/Inner Core: Central component of the wire rope providing support.
  
• Lubrication: Application of oils/greases to reduce friction and corrosion inside wire ropes.
  
• Axial Moving Crown Wheel: A crown wheel mechanism that moves sideways during drum rotation to improve rope spooling.
  

Conclusion
Wire rope damage arises mainly from overloading, abrasion, corrosion, improper handling, and fatigue. Through proper selection, installation by trained personnel, regular inspection, lubrication, and adherence to safe load limits, wire rope service life can be maximized. Preventive maintenance not only protects personnel and equipment but also reduces operational costs related to unscheduled failures and downtime.
Effective management of wire ropes demands awareness of their mechanical behavior, timely detection of wear patterns, and prompt corrective actions to maintain safe and productive lifting operations.