Steel Wire Ropes

What is Wire Rope?

Wire rope is a machine composed of a number of precise, moving parts, designed and manufactured to bear a very definite relation to one another. In fact, some wire ropes contain more moving parts than many complicated mechanisms.

For example, a 6-strand rope with 49-wire strands laid around an independent wire rope core contains a total of 343 individual wires. All of these wires must work together and move with respect to one another if the rope is to have the flexibility necessary for successful operation.


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Stainless Steel Wire

Wire ropes made of stainless steel wire are extremely resistant to corrosion and moreover, to temperature up to 1050°C. Originally only the AISI types 304 and 302 were used for rope making but today almost all our stainless steel wire ropes are made of steel according to AISI type 316 which has better mechanical properties and a higher resistance to electrolytic corrosion, which increased resistance to seawater.

Tensile Strengths of Steel Wire

Steel wire is made in various tensile strength to meet the different requirements of a particular job. For the production of our ropes, we use wire in the following tensile strength


Ranges

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Rope Cores

Ropes are supplied either with fiber or steel core, the choice being largely dependent on the application.

Fiber cores are mainly made from polypropylene. This material has the advantage that it neither absorbs nor retains moisture, and thus it eliminates conditions creating internal corrosion. Polypropylene core will have small variations in size and weight and are less susceptible to damage, especially under moist conditions. The following precautions must be taken during use. Do not use fiber core ropes where these are exposed to high temperatures, i.e. above 90°C, this will damage the fiber core. The fiber core ropes should not be used when multi-layer winding is required as the fiber cores susceptible to crushing.
The steel core is designated IWRC (Independent Wire Rope Core) and normal constructions is 7×7. Steel core proves advantageous in severe working conditions involving a low factor of safety, small drums and sheaves, high operational speeds and wide fleet angles. Steel core tends to preserve the circular cross-section of the rope when it is crushed by over-winding on drums. It also prevents the strands from bridging, (being forcibly against each other) which can result in fatigue failure of wires.

Wire Rope Lay

The direction of lay or rotation of the strands is normally right hand. But some machinery needs left hand lay.

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Diameter of Wire Ropes
The diameter of a wire rope is the diameter of circle which encloses all of the wires. When measuring wire rope it is important to take the greatest distance of the outer limits of the Crowns’ of two opposite strands. A measurement across the valleys will result in incorrect lower readings
Method of Measuring Diametere

Caliper, fitted with jaws broad enough to cover not less than two adjacent strands (see figure)

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Safety Factor of Wire Rope
It is difficult to fix the safety factor for each type of wire rope to be used for various equipments, as this factor depends not only on the load carried, but also on the speed of rope working, the kinds of fitting used for rope ends, the acceleration and deacceleration, length of rope, the number, size and arrangements of sheave and drums etc. The following safety factors are minimum requirements for safety and economy in the common installation.
Rope Characteristics

This chart is purely an attempt to illustrate the relative characteristics of different constructions of wire rope as indicated in the text. No numerical scale is shown or intended.

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Cross Sections of Wire Rope

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Handling & Installation

Must Avoid For Longer Life Of Rope:

  • Twist, loop or kink of wire rope
  • Moisture, dust and acid or sulphuric hume gas
  • Overload
  • Crushing or hammering
  • Sever or reverse bending (S-Bending)
  • Too small sheaves, drums and guide rollers
  • Hard rolling of sheaves and guide rollers
  • Worn groove, broken or soft sheaves and rollers
  • Poor or no lubrication
  • Wrong fitting and spooling on the drum
  • Excessive fleet angle
  • Vibration
  • Obstacles, sand and grit on the surface of operation line
  • Shock too fast start or stop