Consejos de Ropecare

Cuidado en uso

Terminaciones

Inspección y Retiro

Factores de por vida

Cuidar sus cuerdas correctamente es un factor importante en su rendimiento y longevidad. Comprender cómo las cuerdas se ven afectadas por influencias externas y aprender a inspeccionarlas se asegurará de que sus cuerdas son seguras y le ahorrará dinero en reemplazos prematuros.
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CUIDADO EN USO

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Storage

Ropes should be stored in a suitable clean, dry place out of direct sunlight and away from extreme temperature.  Do not store ropes on dirty floors or drag over rough ground – dirt and grit can work between the fibres and cause abrasion damage.  Keep ropes away from chemicals and in cases of long term storage, hose down with fresh water to reduce dirt and salt that can affect the life and efficiency.

Bobinado

3 Strand ropes may become damaged if they are taken from a coil the wrong way.  If this happens turn the coil over and withdraw the rope from the centre – the rope should run correctly without kinking.

Los cables trenzados pueden tener torsión excesiva impartida en ellos por manipulación incorrecta. Idealmente, estas cuerdas deben ser "hanked" en una figura de moda 8 evita poner torsión en y garantizará el funcionamiento libre cuando se despliega. 

Si se suministra en una bobina, se debe permitir que ésta gire libremente sobre un pasador central para que la cuerda pueda ser extraída de la capa superior. Nunca tome la cuerda de un carrete tirado en su lado a menos que se coloque en un plato giratorio.

Sheaves, pulleys and rollers

When any rope is used around a sheave there will be a reduction in its strength and life.  For most non-specialised applications a sheave diameter 8-10 times the rope diameter will suffice, however certain materials such as Aramids may require a sheave size of up to 20 times diameter.

The profile of the groove in a sheave should support the entire rope.  Normally a semicircle of 10% greater diameter than that of the rope is appropriate.  ‘V’ groove sheaves should be avoided since they compress the rope and have points of local friction reducing the life of the rope.  Sheaves should be maintained so that they rotate freely in use.

Winches and capstans

When a rope is wound onto a winch it is important that the wraps are neat and tightly wound.  This can be achieved by winding the rope on whilst under tension.  If the rope is wound on slack then it will be more prone to burying between the turns of the previous layer.

When using ropes on winches or capstans the friction between the rope and the barrel is vitally important since this will determine the amount of slip and the number of turns needed.  This friction is dependent on the rope material and construction as well as the surface finish in contact with the rope.  Since the rope’s geometry will change depending on load the friction can also change slightly.

Visit our page on rope related formulae to calculate how much rope a winch drum can hold.

Productos químicos

The materials used in the construction of synthetic fibre ropes can be affected by exposure to chemicals, often this will reduce the strength of the rope - see physical properties section for more information.  Each of the materials is affected differently by different chemicals, if chemical exposure is expected contact Marlow ropes for more details.  If a rope has been exposed to a chemical that may have caused damage it should be retired from use.  Chemical damage often appears as discoloured or powdery / dusty yarns however the rope can be significantly weakened with no visible effects.

Calor

La exposición a temperaturas elevadas puede cambiar las propiedades de una cuerda. En algunos casos, estos cambios pueden ser beneficiosos, por ejemplo, estiramiento previo y ajuste de calor. Más a menudo los efectos del calor serán reducir la fuerza y ​​dañar la cuerda. Es importante evitar exponer una cuerda a fuentes de calor localizadas oa temperaturas elevadas. Esto debe garantizarse tanto durante el uso como cuando se almacena la cuerda

Calor generado por fricción

When a rope is used on a winch or capstan it is possible to generate enough heat through friction to melt or fuse the fibres of the rope resulting in a reduction in performance.  To avoid this care should be taken to avoid excessive slipping or surging.  Many ropes are designed specifically to withstand friction generated heat - please contact our technical department for more details.

Ultra-violet radiation

Todos los materiales utilizados en la construcción de cuerdas de fibra sintética se realizan, en mayor o menor medida, por exposición a la radiación UV. Siempre que sea posible trate de limitar la exposición de la cuerda a la luz solar. Las cuerdas más pequeñas se efectúan más que las cuerdas grandes, ya que tienen una superficie expuesta mayor en proporción a su volumen. El efecto de la radiación UV en una cuerda está directamente relacionado con las propiedades inherentes a los rayos UV del hilo utilizado en el diseño y la fabricación - ver sección de propiedades físicas para más información.

Abrasión

Todos los cables pueden dañarse si están expuestos a superficies abrasivas o bordes afilados. Se debe tener cuidado para evitar que se corra una cuerda sobre cualquier superficie que no se mueva. Si la cuerda se ejecuta sobre poleas o rodillos deben mantenerse en buen estado con una superficie lisa y deben estar libres para girar.

La abrasión también puede ser causada por la entrada de partículas en la cuerda. Las condiciones en las que una cuerda entrará en contacto con arena, suciedad, arena y otras partículas abrasivas deben evitarse. Los daños causados ​​por este tipo de abrasión pueden no ser visibles en el exterior de una cuerda, pero la resistencia puede ser severamente reducida.

Exposición al agua

The properties of nylon in particular are changed slightly when they become wet. The fibre shrinks, the strength is reduced by up to 15% and the extension increases. You will notice a general stiffening of the rope.  Other materials used in rope making are largely unaffected by even prolonged exposure to water.

Desinfección de cuerdas

In light of the current situation regarding the Covid19 pandemic we recognize that our customers are concerned about how they can stay safe while using our products. 

The information regarding the virus and the transmission paths is constantly evolving as the results of research becomes available. At the moment, transmission from objects is not considered to be the main way the virus spreads. However, it is considered possible.1 

There are a number of ways to reduce the risk of contracting Covid19 from ropes and other equipment that do not require the rope itself to be disinfected. 

Basic hygiene measures:

In order to spread, the virus must come into contact with a mucus membrane. This means that transmission from a rope can be prevented by handwashing or sanitising after contact with the rope and before touching the face. Therefore, in many situations, hand washing after contact with ropes may be more practical than attempting to disinfect the rope itself. 

Quarantine: 

The SARS-CoV2 virus does not survive for a long period of time on surfaces.2 This means that simply quarantining the rope between periods of use will reduce or eliminate the risk of virus transmission. The longer this quarantine period is the more effective it will be. 72 hours will, in most cases, render the virus unviable. Recent studies have shown that when on a surface the virus is sensitive to temperature, 3 this suggests that a warm dry place is most effective for quarantine storage. 

Cleaning and disinfection:

If ropes do need to be cleaned and disinfected, then the following methods may be used: 

Soap: 

Marlow have always recommended that ropes are washed in pure soap. Based on the current guidance we believe this will be effective at combating Covid19 as soap breaks down the virus’s lipid shell rendering it unviable.4 

To wash a rope, immerse the rope in warm soapy water, up to 30 deg C, and agitate well. The rope should be left to soak for at least 20 minutes allowing the soap solution to fully penetrate the fibres. After washing, the rope should be rinsed thoroughly to remove any soap residue. The residue will not harm the rope but may alter the friction properties which could cause unintended consequences in use. After rinsing, the rope should be hung up to dry. Elevated temperatures (greater than 40 Deg C) should not be used to dry the rope. 

While wet, a nylon rope will be weaker than when dry and will have less ability to absorb the energy of a fall. Nylon ropes will shrink and become firmer after washing, this is normal. Normal laundry detergents are not recommended due to the presence of additional chemicals such as surfactants and optical brighteners. If nothing else is available, then detergents can be used as these additives are not anticipated to affect the strength of the rope however, they could cause the rope to be more susceptible to moisture absorption and other minor effects. Isopropyl alcohol: Marlow Ropes have tested Isopropyl alcohol (IPA) on type 6 Nylon ropes including Static ropes, polyester ropes and HMPE ropes. 

In these tests exposure to IPA has been shown to have no detectable effect on the performance. Therefore, it is possible to disinfect ropes with a solution of 70% IPA and water. This solution can be applied by either dipping the rope into the solution and allowing it to air dry or it can be applied as a spray to the rope surface. Caution must be taken when using any Alcohol disinfectant. 

IPA is highly flammable. Inhalation of the vapour can be harmful. Use only in a well ventilated area and not in the presence of any source of ignition or heat. Disinfection in this way should not be done on a regular basis as IPA can be absorbed by Nylon fibres and may act as a plasticizer weakening the ropes over prolonged exposure. 

General notes 

Cualquier lavado o desinfección de cuerdas hará que se degraden ligeramente, aunque solo sea por la acción mecánica del lavado. Por lo tanto, el proceso debe hacerse lo menos posible.
 
Do NOT expose ropes to bleach. This can cause severe damage to rope fibres, in particular the polyester used in in many of Marlow’s arborist products. 

Do NOT expose ropes to oxidizing agents such as hydrogen peroxide. These can severely damage fibres like Nylon without any visible indication of harm.

Do NOT use UV lights to sterilize ropes, the UV will damage fibres, in particular UVC used in industrial sterilization equipment can be expected to do more harm than other types of UV.

Do NOT use elevated temperatures to sterilize a rope. High temperatures can affect fibres, particularly materials like HMPEs. As always, if there is any reason to think a rope’s performance may be in question it is best to retire that rope from service. 

References: 
1 https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/how-covid-spreads.html 
2 https://www.nejm.org/doi/full/10.1056/NEJMc2004973 
3 https://www.thelancet.com/journals/lanmic/article/PIIS2666-5247(20)30003-3/fulltext#sec1 
4 https://www.qub.ac.uk/coronavirus/analysis-commentary/how-soap-kills-covid-19-virus/   
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TERMINATIONS

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SPLICES: Most Marlow ropes can be spliced, this is normally the preferred method of termination.  A good splice using the recommended method should not reduce the strength of a rope by more than 10%.  Visit our splicing page for information on different types of splices
KNOTS: A knot is the simplest way to terminate or join a rope, but will reduce the strength of the rope, sometimes very significantly. This loss is caused by the tight bends and compression found in any knot.  The amount a rope will be weakened will depend on the knot, type of rope and the material from which it is made but can be up to 60%
SEWN EYE: A Sewn eye is made using an industrial sewing machine and are usually only done at the factory or by a specialist.  Sewing has advantages over a splice in that it allows for easy inspection and clear retirement criteria.  However, a sewn eye's strength is a factor of the stitching pattern and thread and not related to the strength of the rope so in many cases will not be as strong as a splice.  Cosmetically it is also not as attractive as a good splice.
TAMAÑO DE LOS OJOS: Wherever possible the angle formed at the throat of a splice when it is loaded should be 30 degrees or less.  This means that the length of the eye when flat must be at least 2.7 times the diameter of the object over which the eye is to be used and the distance from the bearing point to the throat when in use should be at least 2.4 times the diameter. 

Some materials like Aramids and HMPEs will require a larger eye with an angle at the throat of 15 degrees or less.
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INSPECCIÓN Y RETIRO

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Es importante que una cuerda se inspeccione regularmente para asegurarse de que no está dañada y sigue siendo apta para el servicio. Se debe examinar toda la longitud de la cuerda. Los siguientes son algunos de los puntos que deben ser comprobados. El grado en que cualquiera de los siguientes puede ser permitido antes de que la cuerda se retire dependerá de las suposiciones hechas cuando la cuerda y los factores de seguridad fueron determinados.

Abrasión externa

When a multifilament rope is subjected to abrasion then the outer filaments will quickly become broken and a furry finish will develop.  This furry layer will protect the yarns underneath preventing further abrasion.  If this condition does not stabilise and continues to develop then there may be excessive abrasion that could lead to significant strength loss.

A medida que la superficie de una cuerda se desgasta, algunos de los filamentos se romperán, esto resultará en una apariencia esponjosa / difusa. Esto proporciona una capa amortiguadora que protege las fibras por debajo y estabiliza el proceso de abrasión. 

This type of abrasion is typically caused by the environment the rope is used in and can be reduced by ensuring the rope is clean and sheaves etc are in good condition 

Abrasión interna

The rope should be opened up so that the condition of the internal yarns can be assessed.  If they show signs of abrasion then there could be some exposure to abrasive particles or there may be inter yarn abrasion.

Cuando una cuerda se carga o se flexiona, las fibras se frotarán entre sí, especialmente en las intersecciones de las trenzas. Esto puede causar roturas de filamentos que son visibles cuando la cuerda se abre. Esto está relacionado con la tensión y la fatiga de flexión y puede reducirse utilizando poleas más grandes o reduciendo la gravedad de carga. 

Acristalamiento

Si una cuerda ha sido sometida a calor excesivo, entonces puede haber áreas de cuerda vidriada o brillante. El acristalamiento se produce cuando los hilos se funden, si esto ha sucedido, entonces los hilos cercanos también habrán sido expuestos a temperaturas elevadas y habrán sido afectados. Este tipo de daño se ve a menudo si las cuerdas se deslizan en los barriles del cabrestante o los cabrestantes.

Decoloración

This could indicate the presence of dirt that may cause internal abrasion or could be an indication of chemical damage.  If chemical damage is suspected then the amount that the rope has been weakened is very difficult to asses and the rope should be retired.

The example on the left shows a sewn eye termination that failed due to chemical contamination.  The rope was exposed to a chemical that turned the black sewing thread red!  If this had been inspected and retired due to the abnormal discolouration, failure would have been avoided.

Inconsistencias

Si se encuentra que cualquier sección de la cuerda contiene grumos, áreas planas o trozos finos, esto podría indicar que la cuerda ha sido dañada internamente. Este tipo de daño es a menudo causado por sobrecarga o cargas de choque.
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FACTORES DE VIDA

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Outside of the factors already highlighted and explained above, there are a number of other dynamic forces that influence the life of a rope and should be taken into account when calculating retirement points.

Tension fatigue

Tension fatigue will occur any time a rope is loaded.  It is related to the loads that the rope is subjected to.  It is possible to improve the ropes resistance to this type of fatigue by applying marine finishes to the yarn.  The life of a rope can be improved by using at a lower load.  Rope constructions with low ‘construction’ have good resistance to this type of fatigue.

Fatiga de flexión

La fatiga por flexión se produce cuando se flexiona una cuerda. Es importante tener en cuenta esto si se utiliza una cuerda en poleas o rodillos. Esta forma de fatiga está relacionada con la carga y todavía puede ocurrir a muy bajas tensiones. Las construcciones de cuerdas con "construcción" alta tienen buena resistencia a este tipo de fatiga.

Read our news blog on fatigue

Compresión fatiga

This is a rare form of fatigue that only occurs if a rope or components of a rope go into compression.  In this situation ‘kink bands’ can form in the individual filaments reducing their strength.  Compression fatigue can be avoided by maintaining the tension in the rope, using a rope with more ‘construction’ and ensuring that any sheaves and rollers are large enough to prevent any component of the rope from going into compression.  Most fibres are resilient to compression but care needs to be taken when Aramids are used.

Arrastrarse

Creep es una extensión permanente debido al deslizamiento molecular, se produce cuando una carga se mantiene en una cuerda durante un período de tiempo. La mayoría de los materiales exhibirán fluencia hasta cierto punto. La velocidad de arrastre aumentará a temperaturas más altas o cargas más altas. Las fibras más afectadas por fluencia son polipropileno y polietileno. 

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