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Economical Air-Jet Weaving

Newest air-jet weaving technologies improve performance and flexibility while reducing air and energy consumption.

Jürg Rupp, Executive Editor

webwareblanketI n the past, air-jet weaving was often denounced as an energy waster because of the needed air pressure and therefore air consumption. Limitations related to the weft-insertion technology also reduced performance and flexibility, and often, the insertion of the weft was not accurate. Those days are gone with the latest developments of the major weaving machinery manufacturers. Modern weaving machines are fast and flexible, and operate with a considerable reduction in energy.

Some Recent Offerings

The new L5500 air-jet weaving machine made by Switzerland-based Sultex Ltd. is designed to produce a wide range of fabrics. A maximum working width of 400 centimeters also allows cost-efficient production of light- to mediumweight technical textiles. A high weft-insertion rate of more than 2,000 meters per minute is combined with extensive automation, user-friendliness, versatility and flexibility, yarn-friendly insertion of up to four weft colors or types of yarn, and ergonomic design are further features of the machine.

All air-jet weaving machines from Germany-based Lindauer Dornier GmbH are equipped with the redesigned, patented ServoControl® pressure-control system with semi-automatic filling threading in the pilot and main nozzles of the mobile tandem nozzle group. This system allows faster and more flexible adaptation of the air-jet weaving machines to future demands. The new positive weft clamp (PWC) allows all air-jet weaving machines to run without any holding pressure. This extends the spectrum of weft yarns suitable for insertion, including elastane, fancy slubs, soft-twisted yarns and others. For the first time, fabric patterns with large repeats, such as those used for apparel and home textiles, can now be processed on air-jet weaving machines with high productivity and reliable quality.

Belgium-based Picanol's OMNIplus 800 standard air-jet weaving machine is equipped with the highly energy-efficient Sumo motor and with highly effective main nozzles, relay nozzles and valves. The combination of the Sumo motor with the direct drive of the main shaft and shedding motion results in power savings of more than 10 percent in comparison with conventional clutch and brake configurations. In addition, the energy cost for air conditioning is reduced as the Sumo motor dissipates less heat in the weaving mill. The speed of the motor is controlled electronically, without a frequency converter, thus reducing power consumption and permitting greater flexibility. The very short drive train is simple and compact, and the machine is up to full speed right from the very first pick.

Sultex Ltd.'s Active Weft Control System allows further reduction of compressed air consumption by the new L5500 air-jet weaving machine.

Less Air Consumption Is Key

Thanks to the new Sultex Active Weft Control System (AWC), the compressed air consumption is further reduced. According to the company, patented real-time monitoring of the weft yarn makes predictive control of the relay nozzles possible. The main and tandem nozzles ensure gentle acceleration of the weft yarn with minimal air consumption. With the Air Gripper System (AGS), spandex yarns in the weft also are woven faultlessly. Short reaction and blow times make economical compressed air consumption possible. The patented RTC (Real Time Controller) from Sultex is an active control system that influences the current weft insertion rate, optimizing the nozzle blow times. Regardless of the weft being woven, the weaving machine adjusts every weft insertion for minimal air consumption. Depending on the weft yarn and machine width, air consumption can be reduced by 10 to 40 percent.

The air consumption of Dornier air-jet weaving machines can be reduced by up to 28 percent thanks to newly developed relay nozzles, special stretching nozzles and an optional TandemPlus main nozzle, depending on the style program. Dornier's new weft stop sensor, the Slim Throughlight Sensor (STS), is based on the principle of light rays. It provides the highest functional and quality reliability, even on dark weft colors and fine threads down to 20 denier. The compact device can easily be positioned using a clip anywhere on the reed without damaging the reed dents.

The OMNIplus 800's new air supply system and more efficient main nozzles allow improved performance, Picanol reports. With the new generation of main nozzles, the supply pressure for the nozzles can be dropped up to 1 bar. The position of both the fixed and the movable main nozzles is easily adjusted. The air pressure and timing can be adjusted electronically and separately for fixed and movable main nozzles, resulting in reduced air consumption.

The relay nozzles also are optimized. The shape of the nozzles and the position of the holes give an increased pitot value and enable maximum use to be made of the available insertion time. The new Diamond-Like Coating (DLC) on the relay nozzles significantly extends their lifetime when using abrasive yarns. The air lines between valve and relay nozzle have been made as short as possible, thus further reducing air consumption.

Picanol's unique Adaptive Relay Valve Drive (ARVD) system automatically adapts the relay nozzle settings to the behavior of the weft yarn during the insertion, making use of the advanced integrated electronic controls. The result is an absolute minimization of the air consumption; results show an average reduction of 10 percent, according to Picanol.

Picanol's pneumatic catching device (PCD) catches the weft yarn once it has reached the right-hand side of the fabric; a stretching function also is integrated. When using PCD, the relay nozzles do not need to be used as much to keep the weft yarn stretched. As a result, the air consumption of the machines can be reduced by up to 20 percent, according to Picanol.

Picanol's standard OMNIplus 800 air-jet weaving machine is equipped with the energy-efficient Sumo motor and highly effective nozzles.

Higher Productivity

Automatic pick repair effectively reduces the operator's workload and leads to shorter downtimes, maximizing efficiency for increased production and higher machine allocation per weaver. Sultex reports the L5500's chronologically controlled, freely programmable starting mark preventer helps ensure faultless fabric quality.

According to Sultex, the sley drive by complementary cams optimizes sley dwell. In particular with delicate, low-tensile-strength wefts, the extended weft insertion time has a positive effect on the running characteristics. The results are consistently high fabric quality and low energy consumption. The direct servo motor drive eliminates the need to replace wear-prone drive belts and clutch and brake linings, leading to an appreciable reduction in operating and maintenance costs. The run-up with empty picks to prevent starting marks reduces wear on the machine components, eliminates costly power consumption peaks, and avoids short-term power supply overloads.

The air consumption on the Dornier air-jet weaving machines can be reduced by up to 28 percent  thanks to newly developed relay nozzles, special stretching  nozzles and an optional TandemPlus main nozzle.

Removing Heat

Fast-running machines generate more heat than their slower predecessors. The resulting consequences are particularly important in regions with hot climates. As the weave room temperature rises, it becomes harder to maintain the required air humidity at the weaving machine level. Another consequence is that the sides of the warp tend to dry out because of heat radiation from mechanisms in the machine frames. With Picanol's OptiMax machine's water-cooling option, half of the thermal load produced by the weaving machine is extracted from inside the machine. In this way, a new air-conditioning installation can be kept small and energy-efficient, or an existing installation could still be compatible with high-speed weaving.

Compared to a twin machine with the same total number of hooks, the new Stäubli LX 3202 jacquard machine with 18, 432 hooks reduces energy consumption by almost 50 percent.

Low-Energy Jacquard Machine

Shedding and jacquard machines are also playing an important role in the energy balance. Modern jacquard machines use less energy and have higher production outputs than earlier models.

Switzerland-based Stäubli AG's LX 3202 high-performance jacquard machine now is available in a monoblock version with 18,432 hooks. With the expanded number of hooks, the LX 3202 can be used with even wider weaving machines, offering weavers increased output and freedom in creating patterns.

As far as energy consumption is concerned, the new format is highly economical, according to Stäubli. Previously, in an application with 18,432 hooks, the coupling of two machines was necessary - for example, a first machine with 10,240 and a second with 8,192 hooks. Such a combination needed two drive mechanisms and two transmissions to the weaving machine. Calculations confirmed that drive energy almost doubled at equivalent speed and harness type. Compared to a twin machine with the same total number of hooks, the new LX 3202 with 18,432 hooks format reduces energy consumption by almost 50 percent.

According Stäubli, the machine's large format is ideal for high-performance applications in the production of flat fabrics with high thread densities, especially silk and upholstery fabrics. As with other Stäubli jacquard machines, M6 modules are used for individually lifting harness threads. For operator-friendly programming and controlling, every jacquard machine is equipped with a JC6 controller, including a color touch-screen and appropriate interface options for data transfer and networking. The first LX 3202 machines with 18,432 hooks are already installed and are said to meet the high expectations of the users.

July/August 2008