Presentation on

Ropes & Cordages

Contents

•Introduction•Raw Material Used•Structure & Manufacturing •Process & Properties of fibres used in ropes & Cords•Behavioural Characteristics•Rope’s Technical requirements & Testings•Rope Failure•Applications•Market Share & Scopes•Advancements

Ropes & Cordages

• Cordages • Cordage, in its broadest sense, includes all forms and kinds

of rope, string, twine, cable, etc., formed of braided or twisted strands.

• Ropes• Flexible assembly of fibres laid, braided or bundled• Usually has sub structure of long elements: fibres, tapes &

monofilaments etc.• Generally have circular diameter• Relatively thick and have high linear density

Comparison between textile & metallic ropes

Textile Rope Metallic Rope

Stronger when compared on the basis of weight.High energy absorption capacity.Susceptible to Creep.Hysteresis loop is observed during cyclic loading. Sensitive to mechanical damage.No rusting problem.Affected by UV radiation.Heating progressively reduces strength.

Stronger when compared on the basis of size.Poor for wire rope.Do not creep.Does not show hysteresis.

Less sensitive.Susceptible to rust formation.Wire ropes have no effect.Heat influence only when temperature is very high.

Raw Material Used

• Selection On the basis of Cost Properties Performance ↓ ↓ ↓

Cheaper Expensive Natural Synthetic Adequate High

eg. polyolefins eg. Kevlar eg. Cotton eg. Nylon6 eg. Polypropylene eg. Technora Twaron

Attributes of synthetic and natural fibresFibre Positive attributes Negative AttributesPolyamide High extension, elastic,

flexible, High energy absorption capacity, little diameter ratio restriction while working on sleeves or pulleys.

Poor abrasion resistance in wet condition, swelling in water results in strength loss by 10-20%, high extensibility, possibilities of kink formation

Polyester Strong, elongation less than nylon, wet abrasion resistance and fatigue behavior better than nylon

Polypropylene Cheaper than nylon and Polyester, density less than water, soft in handle

30% weaker than nylon& polyester, poor fatigue resistance, poor creep behavior

Kevlar High strength to weight ratio, high modulus, remains unaffected by conventional corrosion in ocean

Poor compressive properties, poor abrasion resistance, low damage tolerance.

Natural fibres Biodegradable, cheap Not durable, weaker absorbs water

Natural Vs Synthetic fibre rope

• Positive attributes • Good gripping surface• Ease of handling• Knot retention• Relatively low recoiling energy• Low cost on size basis but for strength and longevity

• Short comings• Deterioration from biological and environmental

exposure

Manufacturing ProcessNatural Grown fibres

Batching

Combing

Drafting

Spinning

Forming

Laying

Cabling

Manmade staple fibres

Plying

Twine

Rope

Cable laid rope

Yarn

Carding

Cording

Cord

Cabled cord

Manmade filament fibres

Cordage Structure Yarn→ Strand → Rope → Cable

• The first rope machine patent was issued to Sellers & Bantle on May 5, 1807. The Lewis & Clark expedition of 1804 carried a rope machine on the trip to make rope from animal hides. The machine was reputed to be a three strand machine with sun and planet gearing, possibly a Sellers and Bantle machine.

•

The Cordage Structures• Yarn– an aggregate of parallelized fibres compacting into cylindrical form

of extensive, continuous length.(ordinarily by a twisting operation).• Twine- An aggregate of parallelized fibres or yarns compacted into a

twisted structure of continuous length(generally twisted in reverse direction to the component yarns.)

• Cord-Yarns braided or twisted into a structure of continuous length generally less than 3/16 inch in diameter with greater compacting of fibres and structurally balanced to maintain compactness.

• Rope- A flexible, twisted yarn strand structure, diameter greater than 3/16 inch, structurally balanced, ordinary rope is of ZSZ structure.

• Cable- A flexible twisted rope, cord or twine structure, structurally balanced to maintain compactness. The ordinary cable laid rope is obtained by twisting 3 or 4 ropes together and is of ZSZS structure.

Rope Structure• The structure should accommodate a large no. of fibres in coherent,

compact and flexible configuration.

Behavioral Characteristics of different structures

Construction Positive Negative

Twisted It has energy absorption capacity because of its high elongation potential, Bend Easily

Torque free construction under wide load application is difficult

Braided High level torsional stability

Less elongation, Inferior flexing endurance

Parallel Increased strength translational efficiency

Rigid Structure

Pultruded Strong and rigid High bending stiffness

Influence of Construction

Type of Rope construction Tenacity( g/den)3 Strand Laid 2.08 strand laid 2.4Circular braid 2.6Wire rope type 3.5Parallel rope 3.8Parallel yarn 4.2

Influence of Heat

Effect of Temperature on rope strength

Influence of Wetting

Influence of wetting on fibre and rope strengthFibre type in rope Effect of wetting on fibre strength Measured rope strength ratio Wet/Dry manila Gain .97-1.10Sisal Gain .90-1.13Jute Loss .90-.98Cotton Gain 1.04-1.35Nylon Loss .77-1.00

Strength Translation Efficiency

Strength translation efficiency of ropes

Load Elongation Behavior

Rope’s Technical requirements

Rope use can be classified in order of increasing exposure to load.• Occasional low loads eg.lifting slings, barrier ropes• Frequent or permanent low load eg.Antanna stays, permanent buoy or yacht• Occasional high load Vechile recovery ropes, platform tow lines• Frequent and permanent high loadeg.Leg platform tethers, towing ropes or springs

Rope Failure• Creep Failure • External Damage -abrasion -cutting -expose to sunlight• Chemical and Thermal degradation - exposure to a variety of chemicals(such as grease oil, sea water -Heat is generated by mechanical hysteresis within fibres and by internal abrasion• Fatigue failure under long term cyclic loading• Internal Abrasion• Axial Compression, bending and buckling -rope bending -rope twisting -Length Imbalance in rope components

Applications

• Ropes, Cordages and Twines are used for: • Marine Ropes ( For sailing boats)• Mountain climbing ropes• Navigation purposes• Weather forecasting• Deep sea buoy mooring ropes• Military applications Tank recovery ropes and Helicopter abseiling ropes• Supporting antenna• Fishing nets and twines• Twines used for building and horticulture

• Ropes made from waste are used( textile):

Rope of Absorbent fibre, shred and flock material can be developed as storage components in geotechnical sector.

Packaging material as Impact protection spacing and padding purposes.

MERCHANT MARINE

Rope Tow

General Industrial

COMMERCIAL FISHING

RECREATIONAL MARINE

SAFETY, ARBORIST, AND RESCUE EQUIPMENT

Various Ropes Packages

Market Share & Scopes

• Use of Manmade fibres being started after 2nd World war.• Up to 1955,The U.S. hard fibre cordage industry was consisting

of 20 companies.• Chief products are Rope, Baler and industrial twines.• Most manmade fibre rope and cordage employs heavy denier

continuous filament yarns which do not require yarn machinery needed to process natural fibres.

• The future growth potential of new manmade fibres for rope and cordage seems assured, although specific end uses must be selected in which the performance value of these products more than offsets the initial increase in cost over natural fibres.

Nylon As The Most Widely Used Fibre In Cordage

• The most popular manmade fiber for Rope and Cordage is nylon because of its Strength, High shock absorbency, lightness in weight for given strength and resistance to sunlight and weather.

Key Features Which Make Nylon 6 as most abundantly used fiber in Tyre Cord industry:-

World wide about 260 plants of Nylon, about 74% are producing Nylon 6.• Easy and abundant availability of monomer all over the world.• Cost of high elongation and more shock absorbing capacity than

Nylon 66 cords.Nylon 66 is higher in comparison to Nylon 6.• Nylon 6 has greater tenacity

Deepwater fibre Moorings

• The use of steel is safely limited to elastic region, where tension is determined by extension in a linear relation.

• Fibres have nonlinear, timedependent relations between tension & extension, which do not follow the same line recovery as in extension.further fibre ropes stretch irreversibly.

• The systems are also different mechanically.steel moorings follow a curved, catenary path. Light weight fibre moorings are straight & taut.

• Fibre buoyant in water is many times lighter than steel, so that the catenary effect is minimal.

Fig;(a) catenary mooring for steel wire rope & chain. (b)Taut leg mooring for fibre ropes.

Establishment of system There are two conflicting requirement. Holding the platform in

place & minimizing drift due to wind & current is favored by a stiff rope with low extension. However, nothing can stop the platform rising & falling with the waves. This imposes fixed extensions, & if tension generated are to be kept low, in order to avoid damage to the rope a more extensible rope is favored.

Fatigue may occur due to the ‘average’ wave action over long periods of time & possibility of failure in extreme storm conditions.

For deepwater mooring of oil production platforms, polyester is now the favored material. The first commercial moorings to be installed by PETROBRAS in an oil field in the South Atlantic.

Polyester is cheaper than other fibers.Lower instance to extension of polyester.Other advantage of its ruggedness.Resistance to axial compression fatigue is greater than the aramid fibers.Creep and abrasion can be kept within the acceptable limits & this is higher than HMPE.

REFERANCES

• Man-made Textile Encyclopedia.• Textile Horizons by J.W.S. Hearle,part 1&2.• Melliand International by Roland Seidi.• Asian Textile Journal by Dr.Jean-Pierre Peckstadt.• Synthetic Fibres by Dr. N.D.Sharma & S.L.JAIN.• Melliand English.• Textile Horizons by C.C.J de Jong.• Indian Journal of Fibre & Textile Research by R.

Chattopadhyay.• Indian Journal of Fibre & Textile by Hussain I & Pal S.K.