The textile world at a glance: From a look back at ITMA to Industry 4.0

Car body: From the Trabant to lightweight construction

Probably the best known example of alternative lightweight structure is the "Trabi", the Trabant 601, the standard vehicle in East Germany which still enjoys cult status. Its outer paneling consists of short cotton fibers (linters). Since they are not long enough for spin yarn, they are compressed to fleece mats, hardened with phenolic resin, and hot-pressed. Structural stability, weather resistance and especially the availability of raw material were the main benefits of this type of construction.

Changes to automobiles go hand in hand with growing requirements for the automotive industry, which is confronted with scarcer resources, rising raw-material prices and enormous price and competitive pressures, but also with growing vehicle production. In addition to appealing design, customers of automotive manufacturers furthermore expect ever more comfort, functions and safety, while at the same time reduced weight is required.

The use of fiber-reinforced plastic (FRP) is a major improvement in component properties and, in particular, makes lightweight structures possible. Originally developed for aerospace, lightweight construction is also making inroads in traffic engineering. Carbon-fiber-reinforced plastics (CFRP) are finding ever more applications, for example as leaf springs, drive shafts, paneling and even as entire body components.

With a hybrid process (multi-material construction), door-panel weight can be reduced by up to 60 percent.

Compared to injection-molded parts, this translates to a weight reduction of 100 kilograms in a mid-class car, cutting fuel consumption by up to 0.3 liter per 100 kilometers of driving.

Carbon-fiber process – getting down to brass tacks

Nonwovens are used in body-making et al. as lightweight structures. But how is a component made from carbon-fiber, for example a car roof?

Pure carbon appears in nature as graphite and diamond, and both materials are insoluble and infusible and thus unsuited to direct production of fiber. Carbon-fiber initially exists as precursor fibers such aramide, viscose and polyarcrylnitrile fiber and is thermally processed in three-stages (immobilization – carbonization – graphitization) at gradually increasing temperature from 180°C up to 3,000°C.

Inner life: masked nonwovens with a fairly large profile

Innovative materials and finishing procedures bestow automotive nonwovens with weight, function and design advantages. This applies to the vehicle exterior and interior, as well as to visible and masked applications. They can be decorative, but are also used subsurface, where they usually act as carrier material – for instance for synthetic leather and for damping and insulation. In the interior, environmentally-friendly and recyclable materials are increasingly used and usually reduce the mass of the vehicle. The proportion of masked nonwovens in automobiles comes to 90 percent. The areas of application in which nonwovens work behind the scenes include brakes, filters, exhaust systems and batteries.

GEBECON® and EcoStar®

Higher stability and dense surface quality

Compared to standard felting needles, the newly developed EcoStar® style facilitates not only a denser surface quality but also provides a defined fiber transportation and an improved needle life.

However, if a granular or velvety surface aspect is desired then structuring needles are called for.

The structuring process takes place on special-purpose machines and the nonwoven fabric has to be needle-punched before. The product surface can have a velours or rib character or even be structured in geometrical or linear patterns. Structuring needles are differentiated in fork and crown needles. A very uniform velvety surface structure is achieved with crown needles whereas fork needles give a more grainy aspect. In order to achieve a very dense and uniform velours surface a combination of fork and crown needles should be used.

The main areas of application for these products are usually floor coverings, foot mats, rear shelves, door and luggage-compartment panels, and headliners.

In order to achieve required features such as:

• best finish quality
• high surface uniformity
• optimum deep-draw behavior
• dimensional stability

high demands are made on process reliability and efficiency in the needling process.

Fork needles

Fork needles have a simple or multiple intermediate section with a cylindrical working part, as well as rounded fork geometry which ensures perfect interlocking and protection of fibers in the fork during the structuring process. Very high precision in the manufacturing process of the needle prevents needle breakage or bending thanks to the straightness of the needle. Configuring the fork position as a V or D allows the resulting loops to be aligned in the desired direction.

Fork needles are inserted into special structuring machines either with brush-conveyor or lamella plate. Brush-conveyor machines contain a rotating conveyor belt equipped with brush segments. The bristles of the brush segments serve to hold the fibers in place during the needling process so that a velours fabric with uniform loops without distortion results.

Example of use

Crown needles are only installed in brush-conveyor machines, because they need the brush segments to form the loops. They make it possible to achieve an especially uniform, velvety surface texture. Another benefit is simultaneous fiber take-up during structuring, achieved with the high dimensional accuracy of the barbs and exact kick-up.