Safety Hazards in Steel Wire Ropes: Wear
The safety of Steel Wire rope usage has long been a subject of ongoing concern and attention, as major accidents resulting from wire rope damage or failure occur from time to time. To ensure the safe operation of wire ropes during use, it is essential to understand the types of damage and their preventive measures. Although wire ropes come in numerous specifications and varieties and are used in vastly different applications, they generally exhibit similar damage phenomena over time. Common types of wire rope damage include: wear, broken wires, corrosion, deformation, pinching, and overloading, among others.
During operation, wire ropes come into contact with other objects and undergo relative motion, generating friction. Under mechanical, physical, and chemical actions, the wire surface is continuously worn away. Wear is the most common type of damage encountered in wire rope service and is generally categorized into three types: external wear, deformation wear, and internal wear.
1. External Wear
This refers to wear caused by the contact of the wire rope's external surface with sheave grooves, drums, ground surfaces, etc., during use. External wear is subdivided into two types: localized (one-sided) wear and generalized (overall) wear. After external wear occurs, the rope diameter decreases, and the outer wires are worn down. Mitigation Measures: After a certain period of use, methods such as end-to-end or cutting off sections can be employed to change the wear position, thereby extending the service life of the wire rope.
2. Deformation Wear (Peening Wear)
This is a localized wear phenomenon caused by vibration or impact, leading to surface battering of the wire rope. Examples include the rope on a drum being struck by other objects, wires striking each other during hoisting, or pinching phenomena caused by misalignment between sheaves and drums. If a worn surface wire is sectioned, its cross-section at the impacted area appears flattened and spread out wing-like. Externally, the wire width appears increased. Although the reduction in the rope's cross-sectional area might be slight, the material at the local impact point becomes work-hardened, making it highly prone to wire breakage. Mitigation Measures: Minimize occurrences of wire rope impact. Regularly inspect and correct any abnormal interactions between the wire rope and equipment, performing timely repairs.
3. Internal Wear
During use, when the wire rope passes over a drum or sheave, the full load is borne on one side of the rope. The radii of curvature cannot be identical for all individual wires. Due to the bending of the rope, internal wires interact with each other, generating forces and undergoing slight slippage. This increases the contact stress between strands, causing localized indentations or grooves in the wires where adjacent strands cross. Under repeated cycles of tension and bending, stress concentration at these grooves leads to wire breaks, constituting internal wear. Mitigation Measures: Select high-quality lubricants suitable for the working environment. Choose wire rope constructions appropriate for specific service conditions, such as linear contact, triangular strand, full-lock coil (or close-packed), or plastic-coated wire ropes.
