Often made on rapier weaving machines, three-dimensional distance fabrics are increasingly popular in recent years, partly due to the maturity of the manufacturing process. Being lightweight but reinforcement composites, distance fabrics have found uses in construction, transportation and more fields. The same rapier weavers are able to perform other duties such as the production of multi-layer materials for extended technical textile applications.
NV Michel van de Wiele, an international supplier of carpet and velvet weaving machines, offers machinery and know-how on the double cloth weaving principle. Double cloth fabrics have three yarn systems: pile warp, backing warp and weft. With the double cloth weaving process, two superimposed backing fabrics are woven simultaneously, while the pile warp is connecting both fabrics together. Such double fabric is split on the double rapier weaving machine by the pile cutting motion into a top and bottom fabric. When the pile cutting motion is not used, the weaving machines are able to produce distance fabrics, transportation fabrics and other technical fabrics.
The weaving process gives the opportunity to create dense top and bottom layers with almost stretched fibers, and with connections between those layers.
3D distance fabrics allow more applications
Distance fabrics are often produced by velvet weaving technique, which is typically performed on a multiplayer weaving process.
Two or more wefts are inserted simultaneously in superimposed sheds. The distance warp, which is equivalent to the pile warp in the double cloth principle, is interlacing top and bottom fabrics, which are not split. The entire fabric is taken-up and is wound on one roll.
A Van de Wiele double rapier weaving machine, for instance, inserts two wefts simultaneously and lancets fix the distance between the two fabrics to produce distance fabrics. The backing warp ends and wefts form the textile faces and the distance warp ends connect both textile faces together. Some special precautions have to be made, to allow trouble-free weaving.
To form clean sheds and to keep their distance at constant level, in some cases gauges or lancets are used. Lancets are metallic strips which are inserted from the spread rolls into the harness and reed, between top and bottom fabric into the jaw of top and bottom rail. The height of the gauges determines the lowest fabric face distance and forms the step by which the textile face distance can be changed. The textile face distance is programmed with the binding sequence of the distance warp ends. This programming is done by a three position shedding by dobby or Jacquard head. The distance warp ends are woven into the face fabrics on a sequence of a number of picks. These picks are designated as face connecting points. Between this face connecting points, the distance warp ends are not woven into the face fabrics, but interlaced on catching wefts or false picks laying on the top and bottom of the lancets.
Two-face fabrics are defined by the choice of warp yarn type, weave structure, connecting warp system and the finishing matching the respective field of application. The space between the two faces can remain empty or can be filled.
Nowadays, two-face fabrics with face distance of 15 mm up to 1000 mm are produced. Many finishing operations are available: impregnation, plastic and metallic coating and foaming. Thermo hardening and thermoplastic resins can be applied.
Sandwich fabrics find applications in partition walls and covering systems as noise or as heat barriers. The distance and backing materials are polyester HT yarns. The distance between faces is 50 mm to 200 mm. The space between the face fabrics can be filled with foam or with quartz sand.
Cement bags are used in concrete constructions, in dike and slope constructions. Textile face distance ranges from 10 to 20 cm. For backing warp and distance warp yarns polypropylene is used in low tenacity applications and nylon HT is used for high tenacity applications.
Bending resistant sandwich panels
Bending resistant sandwich panels find application in automotive, marine and aviation construction as reinforced light weight walls.
Warp and weft are glass. This fabric is impregnated with resin and is cured. The thickness ranges from 3 to 28 mm. The panels have a light specific weight and have excellent bending strength and stiffness. This distance fabrics are also applied in the field of gas and fluid containers and in ‘in situ’ transformation of single wall fuel reservoirs into double wall versions, as demanded by local legislation. The intermediate space may serve as a leak by-pass zone, which can be monitored.
Flexible two-face fabrics
Flexible two-face fabrics find application as air duct for air-conditioning. The two-face fabric air duct system hangs on the ceiling and is easily adjusted to the form of the ceiling. Low temperature storage buildings are also isolated with two-face fabrics.
Flexible two-face fabrics also find application in the waste industry as protective layer against penetration of harmful materials into the ground.
Other industrial applications are the inflatable air bags for lifting heavy loads as pressing forms and air crafts, or inflatable tumbling mats for gymnastics.
Temporary inflatable structures as boats and shelters are also made of flexible two-face fabrics. For the bottom panel of a inflatable boat a special setup can be used. Distances of up to 70 mm are woven without false picks or catching wefts. Specially shaped spoon lancets are used.
Two-face fabrics with elastic compression properties
By choosing the right material and number of connections for the distance warp, a two-face fabric with elastic compression properties can be made. Advantages are: reduction of confection steps, stability of the product, possibility to add other functions. Applications are in the field of sports (shoes, saddle fabrics for horse and etc), in the medical field (mattresses with extra functions, e.g. cooling or heating).
Multi-layer weaves add value with sandwich construction
The multiple rapier machine is very suitable for the production of multiple layer weaves for strengthening of conveyer-belts, light weight plates and ballistic protection plates.
The multiple rapier weaving machines have a great advantage in production, because typically in this case production speed is defined by the materials used, so by having more than one weft inserted simultaneously, the weaving production is multiplied without change of machine speed.
Also in some cases the use of multiple rapier allows to let some critical yarns pass into the fabric between the rapiers, so without lifting the yarns up and down.
Multiple layers weaves can also be woven in special constructions. Out of these constructions textile profiles are made. In this way a multiple layer weave is changed into a profile after impregnation and then hardened.
Recently, TU Dresden used a Van de Wiele double rapier weaving machine to produce a sandwich construction, where the connecting points between the other layers are made of woven fabric.
A special technique is applied in which the connecting parts are woven in a normal way, but then the fabric is moved backwards to bring together the picks of the outer layers.
Structures with triangle shaped cross sections are possible and have an increased stiffness.
Subsequently, long pile fabrics are made on multiple rapier weaving machines. The connecting yarns are cut on the machine by the integrated cutting system. Typically two fabrics of up to 40 mm pile height can be made simultaneously without lancets. Apart from the application in clothing, long pile fabrics have technical applications in the production of paint rollers, cleaning brushes and polishing mats for automotive and machinery industry.
Artificial grass is woven on a specially designed version of Van de Wiele double shed carpet weaving machine in 5m or 15’ pile width. Two grass carpets, each up to 70mm pile height, are woven simultaneously. Advantages of this process, compared to other production methods, are: better pile fixation (no extra backing needed), better water infiltration, straight pile, design possibilities (jacquard weaving), better pile distribution so that less pile material (-15%) is needed to obtain a product with comparable properties.
Other technical textile applications
In addition to NV Michel van de Wiele, members of the Van de Wiele Group also offer a range of machinery applied to the manufacture of technical textiles.
The IRO and ROJ companies are suppliers of feeders for the weaving industry. Recent developments include the 😄 X2 and HD X2 range, for aramid, carbon or glass fiber, or even for steel or aluminum wire. The Super Elf X2 HD for PP/PE tape and coarse yarns is installed on air jet looms. The low twist unit, specifically designed to weave metal-polyester film yarn or the tape yarn has proven to be an effective solution.
The IRO-Memminger company provides feeders and other accessories for knitting, with a growing market in technical applications.
The Bonas company introduced MJ, LJ and ZJ to allow applications in the technical textiles field, including airbags. Other specific adaptations include optimal springs for the harness, adapted drive system, special coating on the selector boards, covers with connection means for clean air systems.
Griffith Textile Machines has developed machines or machine parts for making technical textiles: machines for geo textiles, for joining paper maker felts, for making scrims, for 3D narrow composites.
This technical information has been sourced.