The nonwovens industry uses roller cards to process staple fibers into nonwovens. The nonwovens fabrics manufactured are used in the traditional textile industry as well as in very different technical areas, from the automobile industry and geotextiles to the hygiene sector and medical industry.
Optimum carding results in the nonwovens industry ensure that each fiber contributes to the desired quality of the nonwoven fabric and that the full potential of the raw material is exhausted.
The composition and choice of card clothing for roller cards thus depends on the end product, the raw material and the carding force required. The geometry of the card clothing teeth is of crucial importance.
For nonwovens, Groz-Beckert supplies card clothing for different applications and also services such as product consulting and recommendations.
Feed roller wires
This card clothing is responsible for uniform feeding of fibers into the card. Coarse and heavy card clothing is generally used because it can control thick fiber mats.
Different feeding systems require adapted card clothing:
- Traditional feeding with two or four feed rollers and one cleaning roller: Usually a coarse interlocking wire type V6 or V8 with 60° to 70° angle is applied. Plain rib type card clothing with intermediate wire can also be used. Grooved rollers are occasionally used and are also equipped with plain rib wire. With feed rollers the fiber mat is transported into the card with the back angle and held back with the front angle.
- Traditional feed table with one roller: The fiber mat is condensed between the feed roller and feed plate and transported to the feed plate tib. This system is primarily used for short fibers (up to 40mm). Here mostly 60° and interlocking type V6 or V8 are used.
- Overhead feed plate: In this case the fibers are gently fed from above into the carding process by card clothing with very open front angle of 80° to 95°. With a cleaning roller an angle of 80° is used, otherwise 95° is applied.
Using licker-in wires, fiber tufts are separated from the compressed fiber mat and fed into the carding process.
Separating fiber tufts of the fiber mat must be gentle and secure. Usually front angles from 70° to 90° are used.
Metallic card clothing for licker-ins are subject to particular loads – great frictional force is generated when the tufts are separated of the fiber mat, leading to wear on the card clothing. Moreover, the fiber mat may include contamination of foreign objects which increases wear.
Transfer roller wires
Transfer roller wires usually have a front angle of 60°. This ensures that the fibers are completely transferred from the upstream roller to the downstream roller.
No carding action takes place within the transfer function. The appropriate teeth geometry and the difference in speed ensure that fibers are smoothly transferred from one roller to another. A front angle of 60° successfully has been proven.
Since it comes into contact with most of the adjacent rollers, cylinder card clothing is considered the heart of every card. The cylinder wire selected is oriented especially to fiber type and fiber fineness.
Cylinder wires normally are the wires of a card with the lowest total height. Depending on the fiber denier, the wires can have very low to high rib sizes. Cylinder wires work in conjunction with many carding rollers and is thus subject to high loads. Groz-Beckert's product range contains especially durable cylinder wires. The resistance of cylinder wires depends on both the quality of the steel and the manufacturing process.
Worker and doffer wires
Worker wires open the fiber tufts down to the individual fibers and mix the fiber components. Doffer wires are responsible for uniform distribution of fibers in the nonwovens.
Standard doffer wires from Groz-Beckert can be smooth or striated. There are also different finishes available so that even very specific applications and every customer desire can be served.
In addition to standard card clothings, Groz-Beckert offers special wires, EvoStep® and SiroLock®.
- EvoStep® is distinguished by a unique undercut on the tooth front. This improves fiber take up and retention by up to 30% compared to conventional wires.
- SiroLock® wire has been especially developed to improve fiber transfer and the quality of nonwovens. It features a unique step below the tooth tip.
High throughput requires high worker and stripper speeds. The geometry of stripper wires has thus evolved toward worker and doffer wire design.
Relatively low stripper wire rotation is used for low to medium throughput. In this case stripper wires with a front angle of 65° to 75° are recommended. High stripper speeds, applied for high throughput, bear the risk of losing fiber control. To prevent fly, stripper wires similar to worker wires are used.
A particular demand on condenser wires is the finishing quality. The condensed fibers must be controlled and completely transferred to the downstream roller.
The condensing process involves a function within the roller card actively carried out with the back angle of the wire teeth. The condensing process is sensitive and can only be carried out with wires that are free of burrs and damage.
Depending on the type of roller card and application, either one or two condenser rollers can be available per doffer. The SiroLock® wires have proven themselves in systems with two condenser rollers and help to secure the condensing process.
Take-off roller wires
Take-off wires gently transfer fibers from the card to the downstream production line.
Groz-Beckert take-off roller wires are available in two different geometries, depending on application. They are distinguished by an especially smooth surface created without chemical treatment of the wires.
In the nonwovens industry, fiber raw material is delivered in bales. During fiber preparation the raw material must be opened and mixed, which brings high stress on the fibers.
This often results in short fibers that subsequently diminish the quality of the nonwovens, and calls for a compromise between opening performance and fiber damage in order to achieve good results. It is thus linked to some fundamental considerations:
- The wires used must be adapted to the process sequence. The opening positions in fiber preparation are adapted to the continuous opening process and equipped with gradually finer wires, whereby the front angle is also adapted to the level of opening.
- Worn card clothing is less efficient in opening the raw material. For consistent quality it is therefore important to replace worn card clothing in a timely way. This is the only way to ensure consistent quality.
Fancy rollers are responsible to lift fibers to the cylinder surface.
Border wires are necessary to securely fasten the beginning and the end of card wires onto a roller and are embedded in the grooves at the edge of the rollers.
Border wires are removed and replaced when ever grinding of a roller is necessary.
Product services Carding
This service includes dismantling, mounting, assembly and start-up of cards.find more
Information about the carding portfolio in form of brochures and videos can be found in the media Center.find more
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