Identification of Steel Wire Rope - Lay

Lay

An important consideration in wire rope construction is the way the wires have been laid to form strands and the way the strands have been laid around the core.

Lay is classified by both direction and type. The lay direction of the wires within a strand and of the strands within a rope is either left or right. Rope lay is further classified as either regular or lang. In a regular lay rope, the wires in the strands are laid in the opposite direction as the strands in the rope. In a lang lay rope, the wires in the strands are laid in the same direction as the strands in the rope.

Regular and lang lay ropes are easily identified by the appareance of the outer wires with respect to the rope axis as shown by the examples to the right.

Right regular and right lang are the most common types of lay in use. Each possesses unique characteristics important to proper selection. Wire rope can be manufactured with five types of lay.

Regular lay ropes are generally more stable and more resistant to crushing. Lang lay ropes are significantly superior in fatigue and abrasion resistance. However, lang lay ropes are more susceptible to crushing and require good winding conditions. They are also extremely prone to rotate under load; they must never be used unless both ends are restrained.

Alternate lay rope combines the best features of regular and lang lay ropes. It offers the advantages of both constructions while minimizing the disadvantages. This construction is ideal where high bending stresses (fatigue) are combined with high rope-to-sheave pressure (crushing); for example, as applied to boom hoist rope.

Rotation Resistant Wire Ropes

Combinations of lays are sometimes employed to achieve rotation resistant properties. In this 19 x 7 rope, (as well as in 8 x 19 IWRC Rotation Resistant rope), the extreme rotational property of lang lay rope is used in the core to counteract the tendency of the outer regular lay strands to rotate in the opposite direction.

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