Composition of steel wire rope

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A steel wire rope is crafted by intertwining individual steel wires to form a strand, and several strands are then enclosed around a central core to create the complete rope. The optimal balance between large wires for maximum corrosion resistance and abrasion resistance, and smaller wires for flexibility and ease of handling, is determined by the number and size of wires.

The construction of a steel wire rope is denoted by a code, such as 6x36-FC, where 6 represents the number of strands, 36 is the number of wires in each strand, and FC indicates the type of core.

Steel wire rope construction - Lifting KnowHow

From raw rod to final rope

The process of manufacturing a steel wire rope involves various stages, as illustrated. The initial material is wire rod, cold-drawn to different dimensions and strength grades.

The wire may be untreated (bright), galvanized, or stainless, with galvanized wire offering enhanced protection against corrosion.

Strands are formed by laying individual wires around the core, employing various configurations such as ordinary lay, Seale, Warrington, Warrington-Seale, Filler wire, and Compacted strand.

Steel wire rope from coord to rope - Lifting KnowHow
Rope gradeWire tensile strength gradesHardness app.
ENAPI 91Min kp/mm2Max N/mm2Max kp/mm2Max N/mm2Brinel HBRockwell HRC
1570PS14013701801770405/42545
1770IPS16015702001960445/47049
1960EIPS18017702202160470/48051
2160EEIPS20019602202160480/50052

Strand lay and core selection

Strand lay refers to the arrangement of wire layers, with cross lay and parallel lay being common. The rope's core, crucial for support, can be made of fiber, steel, or solid plastic. Codes like 6X19-FC signify a fiber core, while -WSC and -IWRC denote single-strand steel and steel wire rope cores, respectively. Some ropes even have a plastic-encapsulated core for increased stability, wear resistance, and reduced corrosion.

Steel wire rope lays - Lifting KnowHow
Steel wire rope strands - Lifting KnowHowSteel wire rope core structure - Lifting KnowHow

Rope lay and rotation resistance

Rope lay describes the direction of wire twist, with options like ordinary hand lay, Lang's lay, right hand lay (zZ), and left hand lay (sS). Rotation-resistant ropes counteract twisting, utilizing layers laid in opposite directions to balance forces.

Steel wire rope lays directions - Lifting KnowHowSteel wire rope strands rotations - Lifting KnowHow

Preforming and lay length

Preforming introduces a helical shape to strands, minimizing twisting tendencies and facilitating easier handling. Lay length, representing the helical length of wire or strand, is crucial for the rope's longevity and must be maintained for optimal performance.

Steel wire rope lay length - Lifting KnowHowSteel wire rope preforming - Lifting KnowHow

Breaking load definitions

Breaking load terms include the minimum breaking load, which is the lowest force at which the rope fails during testing, and the calculated breaking load, determined by the metallic areas of individual wires and tensile strength grades. The latter considers the square of the rope's nominal diameter and incorporates a standard spinning loss factor resulting from strand and wire twisting.

Steel wire rope breaking load banner - Lifting KnowHow

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