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Features

A New Technology For Woven Ropes

MultiSphere technology developed by Jakob Müller enables production of ropes using a new narrow fabric needle loom.

Dr. Roland Seidl

U p until now, ropes have been manufactured exclusively on braiding machines. However, with a revolutionary method from Switzerland-based narrow weaving machinery manufacturer Jakob Müller AG, Frick, rope-like structures can now be produced on new narrow fabric needle looms. The differences from conventional machines relate to the reed, the fabric guide and the take-off.

It is highly possible that ropes were the first technical textiles in human history. The ancient Egyptians produced ropes for the construction of the pyramids from fibers weighted with stones and tied to wood. The traditional production method for ropes is braiding. This creates a textile composite, which is thicker and stronger than the individual strands. A braid is a complex structure that is created by plaiting using three or more strands of flexible material such as textile fibers or wires, for example.

Muller1

Figure 1: Jakob Müller’s NG3M narrow fabric loom,
shown here, and its sister model NC2M feature
MultiSphere technology for weaving ropes,
twine and other such products.


Woven Fabrics With A Circular Cross-Section
Using Jakob Müller’s MultiSphere technology, ropes — with or without cores — and twine and other such products can be woven on the new NC2M and NG3M narrow fabric needle looms (See Figure 1). “M” stands for “MultiSphere.”

Compared to the braiding process, this innovative technology facilitates the cheaper manufacture of ropes and twine with similar and frequently enhanced mechanical characteristics. Among the related advantages are high productivity; longer, knot-free lengths; and the avoidance of layer slippage in the case of core ropes. MultiSphere technology also allows narrow fabric producers to enlarge their product portfolios and achieve higher production at reduced cost.

The ropes and twine produced can be used in the clothing sector as cord, laces and shoelaces; in the sports segment as important components for water sports; for camping; and in the construction, agriculture and horticulture industries; among other sectors. Rope- or twine-like products also are used as cord, wallpaper edging or drawstrings for blinds. Clotheslines, dog leads and gift string
constitute another group of possible applications.

The Technology
MultiSphere machines are based on proven narrow fabric weaving technology that is used worldwide. The machines are characterized by robustness and high production speeds, and are designed for a variety of rope diameters. The NG3M is recommended for diameters of 1 to 7 millimeters (mm), and the NC2M for diameters of 6 mm and above. Machine operation is straightforward and can be completed by persons familiar with narrow fabric looms. Suitable aids are available for the creation of chains for pattern control and product development. In the case of simpler structures, curved cam plates can be utilized for heddle control, which provides increased production speeds. The warp threads can be taken off bobbins from a creel or via standard warp beams. Special solutions are also possible with regard to product laying or winding.

The Needle Looms
The idea of weaving ropes on a needle loom necessitated the redesign of a number of components in order to ensure that the rope receives a three-dimensional (3-D) form and can be taken off without slippage. In addition, in order to accommodate this 3-D form, the shed opening had to be as large as possible. For the weaving of ropes, the new narrow fabric looms differ from conventional machines with regard to the reed, the fabric guides and fabric take-off.

As a rule, coarse reeds are used in order to attain a round rope form. Only two pitches are required for weft beat-on; while the large shed opening necessitates the use of reeds with increased headroom. Figure 2 shows the reed with the weave formation zone. A rope with a core and a diameter of 7 mm is being produced.

Muller2
Figure 2: The new looms use reeds with increased
headroom and feature a newly developed fabric guide.


The standard guides in a narrow fabric needle loom have the task of holding the fabric as steady as possible during reed beat-up. As a rule, the fabric holder is flat and exerts a certain degree of pressure on the fabric in the formation zone. The newly developed and patented fabric holder supports the formation of the 3-D rope structure and guarantees the precise guidance of the rope weave.

Fabric take-off is completed by means of enlarged rollers, whereby multiple winding is utilized to increase the winding angle. In combination with a roller coating that offers an increased blocking coefficient, this process provides constant take-off force.

The feeding of sheath and core threads takes place via a compensation device, which also supports the creation of a 3-D form.

Various fabric patterns are used to achieve rope-like structures with specific stress-strain and surface characteristics. As a result of the fabric texture, linkage between the individual layers of the rope-like structure can be attained, thus preventing dangerous slippage when the rope is stretched over sharp edges (See Figure 3).

Muller3
Figure 3: Inner and outer layers of multilayered ropes
can be linked by means of weft threads,
thus preventing slippage.
 
The Advantages
Production of the new woven rope-like structures offers several important advantages:
•    Productivity is improved. With six heads, a speed of 2,000 revolutions per minute is reached, and 10,000 meters of rope can be manufactured in three shifts. A comparable braiding machine produces 1,580 meters.
•    Longer, knot-free items are produced because longer yarn lengths are available on the bobbins and warp beams compared to braiding bobbins. Moreover, while in line with the filament yarn count, a braiding bobbin has an average yarn capacity of 1,700 meters, and the warp beam allows the winding on of more than 5,000 meters. A creel with reserve bobbins also may be used.
•    The linkage of the various layers by means of weft threads rules out slippage in multilayered ropes.
•    Good mechanical characteristics include lower strength at 1 and 2 mm while meeting the German Institute for Standardization requirements, comparable strength between 3 and 4 mm, far higher strength than braided structures at a thickness of 5 mm and above, and stress-strain curve similar to that found in braided ropes.
•    Various surface structures are possible through the selection of differing fabric patterns.
•    Production and manufacturing costs are far lower than for braided ropes.

MultiSphere technology is set to revolutionize rope production. In addition to the mechanical and surface characteristics that can be attained, a reduction in production costs constitutes an important criterion for an investment decision. The first narrow fabric looms are already in industrial production.


Editor’s Note: Dr. Roland Seidl is headmaster of the Jakob Müller Institute of Narrow Fabrics, Frick, Switzerland.

July/August 2009

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