WIRE ROPE OVERVIEW WIRE ROPE SIZE AND MEASUREMENT Wire ropes are described by their diameter, (mm), and are measured across the widest point, The Crown, as shown below.
CONSTRUCTION The size and number of wires in each strand, as well as the size and number of strands in the rope greatly affect the characteristics of the rope. In general, a large number of small-size wires and strands produce a flexible rope with good resistance to bending fatigue. The rope construction is also important for tensile load (static, live or shock) abrasive wear, crushing, corrosion and rotation. The number of strands and wires will influence the flexibility, fatigue and wear resistance of any given wire rope. Rope selection is often a compromise. Generally the more load bearing wires in the rope the greater the flexibility, however the smaller the wires the less abrasion resistance. For example, the same nominal diameter 7 x 7 wire would be less flexible than a 7 x 19 wire, hence a large number of small size wire and strands produce a flexible rope with good resistance to bending fatigue wear. The construction of wire rope is defined by the number of outer strands (first number), and the number of wires within that strand (second number) and then by the arrangement of the wires in each strand (shown in brackets). The wires in each strand can be arranged in several ways, for example a 6 x 19 construction the 19 wires in each strand are laid 9 around 9 around 1 centre wire.
CORRECT WAY
INCORRECT WAY
ALL WIRE ROPE IS MANUFACTURED WITH THREE BASIC COMPONENTS: WIRES, STRANDS AND A CORE.
CORE The core of a steel wire rope serves as a foundation for the strands, providing stability by keeping them in place throughout the life of the rope. Wire ropes can be supplied with either a fibre or wire core. GRADE Wire rope can be manufactured in different steel grades, which directly affects the Minimum Breaking Force, (MBF). The higher the grade the higher the MBF. Common wire grades include: 1570, 1770, 1960 and 2070. FINISH Wire Ropes can be supplied as Black (self-colour), Galvanised or Stainless Steel. Wire rope is lubricated at the time of manufacture, to help reduce friction between wires and strands, and the friction between the rope and drum or sheave. In addition, the lubrication retards corrosion and inhibits possible rotting of the fibre core.
6 X 19 Fibre Core Wire
7 X 7 Wire Strand Core
4 | BUNZL SAFETY & LIFTING | SAFETY PRODUCTS CATALOGUE VOL2 4
7 X 19 Wire Strand Core
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