LATCH & BATCHELOR LTD

Rope components

Wire

The Raw Product

Today's wire rope manufacturers require wire that is tailor made for rope designs of ever increasing complexity, whilst conforming to exact specifications.

Steel manufacturers themselves for over a century Webster & Horsfall nowadays buy their requirements from Specialist British and Swedish Mills insisting on purity, perfection of surface finish and exactness of analysis and micro-structure.

The product range's from 0.004" to ½" and encompasses an infinite variety of round, shaped and flat wire to exact size and specification.

The Process Route

Raw rod is first subjected to a heat treatment process to achieve the homogenous granular structure required for ductile wire of high strength.

The process consists of heating the rod to a temperature above its point of transformation for a predetermined period of time and then quenching in a molten lead bath. Oxide scale accumulated during this process is then removed by immersing the rod in a tank of acid, rinsed with water and then covered with a layer of phosphate to aid lubrication during the drawing process. The wire is then cold drawn though tungsten carbide or diamond dies, the number of passes determined by the size, tensile, torsions and flexions required.

Production Scope

From top quality steel rod we manufacture carbon, low alloy and stainless steel, round and shaped wire in the hard drawn, hard rolled, oil tempered and annealed condition with many associated finishes for the spring, music, engineering and wire rope industry.

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Wire specifications

Carbon Steel Wire

Wire Specification BS 2763: 1982

• General Purpose Wire: Steel containing a maximum of 0,05% sulphur and phosphorous.
• High Duty Wire: Specially selected steel containing a maximum of 0.035 sulphur and 0.030& phosphorous.

Tensile

Ranges include:

• 1370 N/mm²minimum: (140 kgf/mm²) (89 tonf/in²)
• 1420 N/mm²minimum: (145kgf/mm²) (92 tonf/in²)
• 1570 N/mm²minimum: (160 kgf/mm²) (102 tonf/in²)
• 1770 N/mm² minimum: (180 kgf/mm²) (115 tonf/in²)
• 1970 N/mm² minimum: (200 kgf/mm²) (127 tonf/in²)

Galvanising

Zinc coatings provide sacrificial protection for the bare steel wire against corrosion. The two types supplied comply with BS 443:1982, which are:

• Class A: Generally used in marine applications it has the heavest weight of zinc coating thus, the specification for torsions and flexions is lower than for ungalvansied wire.
• Class Z: Or Anti-Corrosive, this wire is drawn after galvanising resulting in a lighter zinc weight than Class A but retains the ful physical properties of ungalvanised wire.

Stainless Steel Wire

Wire Specification BS 970:1983 Part 4 Grade 316 S33

• FMB: Alloy steel containing 18% chromium, 8% nickel and 2.5% molybdenum for marine and special engineering applications.
• Low Permeability: Non-magnetic stainless steel wire for Ministry of Defence Naval mine-sweeping operations.

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Rope construction

A wire rope is made up of individual steel wires spun into a strand. The strands are then closed over a central core, generally hemp, synthetic fibre or steel. Construction of wire ropes are generally expressed as follows:

1. Number of strands
2. Number of wires in strands
3. Lay-up of wires in strands
4. Type of core
5. Direction and type of rope lay

Eg: 6x19 (12/6/1) Fibre Core Right Hand ordinary Lay

Diameter

The diameter of a rope is the diameter of the circumscribed circle.

Strand Lay

Stranded ropes are constructed in either Ordinary Lay (otherwise known as Reverse Or Regular Lay) or Langs Lay. Unless otherwise requested all ropes are made with right hand final lay.

• Ordinary Lay

  
  With ?ordinary Lay? the helix of the wires in the strand is in the opposite direction to that of the strand in the rope, consequently the rope is stable and easily handed. The wearing qualities, however, are relatively poor due to the point contact on the crown wires in the strands. Having a smaller bearing surface abrasion is quicker at this point.

• Langs Lay

  
  In ?Langs Lay? rope the helix in the wire is in the same direction as that of the strands in the rope. Due to the surface pressure being spread over a longer length of one wire in the strand, the resistance to abrasion is greater than with ?Ordinary Lay?. However, as it produces a relatively high torque value under working conditions it must not be used on applications where on end of the rope is unrestrained or free to rotate, otherwise unravelling may occur.

Wire Lay

• Cross Lay

  
  A construction in which the strands are made in several operations using the same wire size throughout, and consequently the wires cross the crowns of the underlying wires
  

• Equal Lay

  
  A construction made in one operation in which all the wires have the same length of lay. This eliminates internal cross nicking and forms a compact strand of high metallic content giving a higher breaking load and better bend fatigue than Cross Lay.
  
  There are three types of Equal Laid Ropes:

Filler: The cover is supported by the inner wires and small filler wires lying in their interstices.
Seale: In which there are the same number of inner and outer wires. The outers lying in and being supported by the valleys of the inners.
Warrington: The outer layer formed from pairs of different wire sizes. The smaller outer wire lying on the crown and the larger supported by the groove, of the inner wires.

Cores

Wire ropes are supplied with either fibre or steel cores depending on application. Their principal function being to provide support for the strands and to maintain their correct positions under working conditions.

• Fibre Cores

  These are manufactured from natural fibres such as sisal, hemp, jute, and cotton or, synthetic fibres such as polypropylene.
  
  Fibre Cores provide:
  1. Increased flexibility
  2. Reservoir of lubricant - thus reducing internal corrosion and wear between wires
  3. Resistance to rotting with synthetic cores.

• Steel Cores

  Supplied in two types:
  1. Independent Wire Core (IWRC) which is itself an independent wire rope. (fig1)
  2. Wire Strand Core (WSC) used on ropes smaller than 13mm diameter, and normally the same construction as the outer strands. (fig2)
  Steel Cores provide:
  1. Increased breaking load for the rope.
  2. Resistance to crushing, distorsion and heat.
  3. Better support for outer strands.
  4. Better resistance to shock loading and stretch.

Preforming

Preforming is the process of pre-setting the wires in the strand and the strands into the rope into the natural helical form they will assume in the completed rope.
Advantages of preformed ropes:

1. Rope remains inert when cut.
2. Ends will not subsequently unravel.
3. Greater resistance to fatigue.
4. Less tendency to kink.
5. Easy to handle during installation.

Ropes are generally supplied pre-formed unless otherwise specified by customer.

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Rope lubrication

It is seldom appreciated that a wire rope even in its simplest form is a complicated and carefully designed piece of machinery, with many moving parts. As such it is subjected to internal friction, external abrasive wear and corrosion.

Suitable lubricants are applied during manufacture to the core, the strands and finally the finished ropes; and posses the following properties:

1. Good adherence.
2. Resistance to penetration of water and other corrosive elements.
3. Anti-oxidants - to resist ageing.
4. Alkaline based emulsifiers - to neutralise acid.
5. Encompass a range of ambient temperatures without degrading.
6. And be non-inflammable.

The weight of stranded ropes thus lubricated will be approximately 3% higher than shown in the product listings.

When in service it is important to regularly clean the rope and then re-apply a suitable external dressing which will help replenish the manufacturing lubricant and extend the working life of the rope. Frequency of application will depend on individual site conditions.

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Wire Servings

Before cutting, rope ends must be secured with a wire serving. Simple preformed ropes can be simply served as detailed in BS 6570.

Live ropes and more complex ropes such as non-rotating and multi strand ropes will require at least 2 servings each side of a cut. Each serving should be at least 2 rope diameters in length.

Locked Coil and Spiral strand ropes need very special servings of long length applied with a serving mallet or the Latch & Batchelor Apostle.

All wire servings need securing by twisting the wire ends or in the case of special servings soldering is the usual method.

If there is any doubt as to the type of serving or method of application, please contact our technical or sales department.

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