Before iron took over, one or another fiber rope had been used for thousands of years. For the past two centuries, steel wire has been in a monopoly position in certain fields. But is optical fiber about to usher in a historic comeback? Simon Hastlow reports.

The 21st century has witnessed major investments in the research and development of fiber ropes. Tried, tested and evaluated different raw materials, so that we have reached the point where choosing between steel wire rope and synthetic rope is no longer simple to choose which is effective. It is about which is best for a particular elevator.

You might imagine that traditional wire rope manufacturers have been struggling with the growth of fibers; on the contrary, several companies have cooperated with crane manufacturers, have embraced this technology, and clearly see the benefits of these two materials.

End users are also becoming more aware of the advantages of each product in specific situations.

"If you can choose from two slings for the same lifting work, and one sling only provides breaking load information, while the other sling has breaking load, verification load, failure load analysis, and all failure modes are Adopted to focus on the design, manufacture and testing of the sling. Before you start using the sling, you can get more information about the sling," Marc Eijssen, global technology and business development manager of DSM Protective Materials, a Dyneema fiber manufacturer Say.

"We really focus the attention of end users and project owners on the whole "fit for purpose" approach. Now we see more contractors and project owners agree with this. They need reliable and safe products. When dealing with safety and reliability issues, we tend to consider more than one parameter called breaking load. Since the sling is an important link between the payload and the crane, cost is never the only selection criterion,” Eijssen added.

The main component of synthetic ropes used in the lifting and crane industries is ultra-high molecular weight polyethylene (UHMWPE), a thermoplastic polyethylene. It is also called high modulus polyethylene (HMPE). The reason why it is so popular in this field is its extremely long molecular chain. This long chain more effectively transfers the load to the polymer backbone by strengthening the intermolecular interaction. Until recently, it was derived entirely from crude oil, but DSM also began to produce bio-based HMPE made from renewable resources.

Interestingly, some synthetic rope manufacturers use DSM-made HMPE in their own ropes.

Manitowoc was the first crane manufacturer to provide synthetic ropes in its cranes, and in 2012 it partnered with American rope manufacturer Samson. The company started to provide K-100 synthetic ropes for rough terrain cranes in 2014 and now provides them for boom trucks, truck mounted cranes and all terrains.

At Bauma 2019, Liebherr launched a new EC-B series of flat-top tower cranes. The series includes eight cranes, three of which are equipped with soLITE high-strength fiber ropes. SoLITE was developed in cooperation with rope manufacturer Teufelberger and tested on Liebherr tower cranes and mobile cranes. The structure of SoLITE is unique in the field of fiber ropes. It includes a core with outer fibers.

Polish crane rental company Mazur Zurawie ordered a 10-ton Liebherr 240 EC-B 10 flat-top at the event and delivered it earlier this year. The crane has a boom length of 68m and a lifting capacity of 2.85t at the tip of the boom at 65m.

It is the first product equipped with soLite fiber rope. Company owner Krzystof Mazur said: “I want to be one of the first people to own a fiber crane because its performance is very suitable for our fleet.”

Last year, tower crane manufacturer Wolffkran acquired shares in Trowis GmbH, a young German company dedicated to the development and production of high-performance fiber ropes for the lifting and material handling industries.

Wolffkran participated in the company when the company's ropes were still in the testing and development stages. Trowis high-performance fiber rope has dual redundancy, self-monitoring composite fiber structure and sensor elements integrated in the rope, enabling it to monitor possible fiber breaks in load-bearing rope components and alert crane operators in real time.

“Gradually, we are seeing more and more companies interested in new cranes equipped with fiber rope technology. Because this gives them the opportunity to increase the payload when using the same type of crane,” Eijssen said. Therefore, it is clear that even though steel wire rope still accounts for 80% of the overall market share in the lifting industry, the advantages of both materials have been recognized and utilized.

When discussing the advantages of wire rope, people's response is usually "everyone knows where they stand with the wire rope." Since wire rope has been used for a long time, it has a lot of experience. But this should not be an obstacle to exploring the benefits of synthetic materials. As mentioned above, some areas have their own advantages.

"In most cases, the test methods are very similar or basically the same. Synthetic ropes will be affected by changes in tension, so elongation must be measured. Everyone has their own information about the cyclic load, number of cycles and terminal, pin size ( D:d ratio), pulley groove size, shape and speed details," said a representative from Yale University Rope Company.

"Many synthetic test methods were originally based on wire, but were later adjusted to better suit synthetic materials. If you want to change the wire, then elongation and settings are essential measurements, such as D:d (if used for lifting Basket) or pulley D:d and the shape and size of the Grove used to move the rope."

Eijssen from DSM added: "The company is also asking,'When do I know when I need to discard the fiber rope and sling?" It is obviously easier to see the use of wire rope. When the strand is broken, you can Seen from the outside. You can use non-destructive testing methods (such as magnetic screening of the rope) to understand the condition of the wire rope.

"With fiber rope technology, things have become a bit difficult. Companies have begun to study the use of monitoring tools, temperature sensors, cameras and thermal imaging cameras to describe the appearance of ropes during use. They need to build this information through specialized research activities and dynamically. To ensure that the fiber remains safe and reliable. The industry needs this information to optimize the use of fiber rope for future generations."

However, in areas where most of the factories used are provided by leasing companies, additional monitoring equipment and procedures posed another problem. Eijssen said: "Crane companies don't want to add a lot of extra components to the crane just to indicate and monitor the status of the rope." This is one aspect of the wire maintaining a clear edge.

"WireCo has a reputation for special and special ropes in the lifting industry with its special crane rope brands Casar and Oliveira. Casar Product Marketing Director Christian Schorr-Golsong said: "The focus is on Type 1 anti-rotation ropes, which means 15 strands and The above foreign shares. "

"The most powerful safety feature of our steel wire ropes is the special design of the ropes and how we produce them. If a rope shows signs of being discarded, there will always be a question, and that is the remaining life of that rope.

A safety rope has sufficient reserves to cover the time between discarding and breaking of the rope, so that if the discarding point is not realized for any reason, the user will not be in trouble. Our ropes have been designed and tested to provide a well-balanced life reserve for the ropes. "

With the increasing complexity of testing and monitoring procedures developed and implemented by several different manufacturers, the call for standardized methods has led to the emergence of FEM guidelines and is moving towards ISO.

"Developing a synthetic rope that can replace high-performance anti-rotation ropes is a challenge and not an easy task. We are talking about a very safety-related component in a crane, and there is no room for reckless activity. This is in terms of cranes and ropes. One of the main reasons for establishing a team of experts to develop standards for the use of synthetic ropes in cranes," Schorr-Golsong said.

"Based on a lot of discussion, hard work and testing, FEM 5.024 guidelines were developed and published. Now, ISO-level guidelines have begun to work. These are important steps to increase acceptance and are therefore an investment in the further development of synthetic ropes for cranes. "

Even if it goes back to the earliest product, synthetic fiber rope has only been used for more than 20 years, and the early adopters are mainly marine and recycling users. In the crane and lifting industries, optical fiber still has a long way to go, but new developments and increased awareness will certainly only increase market share.

A representative of Yale Cordage said: “Different end uses will drive innovation in synthetic rope design and require rope manufacturers and end users to clearly understand the needs. The value proposition presented by synthetic materials will allow new equipment in all types of crane applications. Close collaboration in the evolution of the concept. This will enable users and machine designers to take full advantage of the weight reduction and high strength of today’s synthetic materials."

Schorr-Golsong added: “Today the market share of synthetic ropes and steel ropes is still very low. In the mid-term, we see opportunities for synthetic materials to occupy 20-30% of the market.

The crane market and the rope market used for this equipment are very stable and have not undergone fundamental changes. What is always interesting is the improvement of cranes to achieve higher lifting capacity, easier operation, less maintenance, lower cost or longer life of old ropes. Any improved technology provided here is welcome. "

Compared with general construction cranes, DSM especially believes that the fiber market in the field of engineering lifting is expanding.

"We clearly distinguish between general lift and engineering lift operations. General lifts usually require a higher design factor. But this factor is always affected by the end user. If they don't know how to handle the product, then the design factor is meaningless. ," Eijssen said.

"In engineering lifting operations, companies generally understand risks better, which provides an opportunity to transform risks into safety and reliability, and it is possible to reduce design factors without affecting safety and reliability.

The company understands risks better and sets parameters clearly in advance and analyzes better. The technical specifications and characteristics of the use of fiber ropes can mitigate these risks. "

"There are restrictions, but if you know them, they can be handled. The wear of fiber ropes on rough surfaces is considered a complicated situation, but if you know this problem, you can consider it when designing slings. For example. , You can add specific sleeves to the specific parts of the sling that need to solve the wear problem. It has been integrated into the design and integrated into the user manual. As long as the industry is aware of this problem, they can be accepted."

Redefine the limits of synthetic ropes

An American shipyard was frustrated by the large, heavy slings made of steel wires and chains that dragged down its productivity. As they build larger, better, and more skilled ships, slings have brought new setbacks to workers.

The assembler had to hoist the assembled parts onto the hull wire sling weighing more than 135 kg. The heavier lifts are carried out outdoors, the slings can weigh up to 100 tons, and workers rely on cranes to move them.

Shipyards already use synthetic slings in certain jobs, but some problems need to be solved before they can switch the heaviest lifts from steel to synthetic slings. One of them is wear and tear: under heavy load, the gathering of the shackle or pick point or the slight movement of the pick can tear the sleeve of the sling. Another issue is stiffness. The last one is stretching, because the lift can be carried out under the ceiling height limit, so the sling needs a low and predictable stretching level.

After a year of development and testing, Yale Cordage produced a synthetic multi-part sling with the same length, tensile properties and stiffness as the sling they used, with the same capacity, but 85% lighter than the wire.

Fortis2 is a multi-part sling made of Unitrex XSTM Max Wear synthetic cable. Its core is Honeywell Spectra HMPE fiber, wrapped with a neoprene coating, and the outer layer is woven with a tough, high-strength polyester jacket. Since the core fibers in Unitrex are laid in parallel to eliminate torque and then sealed in place with a layer of neoprene, the fibers maintain their optimal strength and exhibit stiffness equivalent to that of the wire.

The 55-foot (17-meter) Fortis2 sling has a rated weight of 100 tons and weighs only 75 kg. It can be lifted and moved without a crane or forklift. In addition, stocking 60 tons, 80 tons and 100 tons of slings does not have a real operational advantage, because 100 tons can handle all the options in the yard.

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