Textiles for technical uses

Technical textiles have some characteristics in common with traditional fabrics, but also other specific and different characteristics.

The elements which should be taken into consideration to identify this sector are:

· the raw materials

· the technologies

· the products and the end-uses.

Raw materials

Raw materials for the production of technical textiles are virtually all fibres, with preponderance of man-made fibres.

Technical textiles are still nowadays composed largely by traditional fibres, entirely similar to the raw materials of traditional textiles.

Innovative fibres are going however to be created even more in the future; these fibres have new and special features unobtainable in nature, aimed also at attaining performances which often conflict with each other (e.g. tenacity and softness, durability and degradability after use) which cannot be obtained with traditional fibres.

These high performance fibres (HP fibres) have however a cost considerably higher than traditional fibres.

Their cost is in fact closely related to the exceptional performances imparted by them, consequently their use has to be weighed depending on the real requirements of the single end-use.

Production technologies

Many of the technologies used for technical textiles are the same as for traditional textiles, from spinning to weaving until making-up, with some adjustments and modifications.

In some cases, however, specific technologies are used, which find exclusively application in technical textiles: f.i. nonwoven production, three-dimensional weaving, braiding, composite formation.

In this regard we point out that nonwovens overlap to a wide extent technical textiles: in fact nonwovens are largely applied in technical textiles, of which they have an important share.

Products and applications

Textiles for technical uses are products which are assessed on the basis of a series of factors which are the same used for assessing traditional textiles, but refer to a different hierarchy of values in terms of importance and of priority.

In reality we are facing two different worlds which however have some overlapping areas and some zones of common interest:

· they use the same kind of raw materials

· they use the same processes, and often the same machines

· they involve the same kind of operators

· in many cases the producers of technical textiles come, more or less directly, from traditional textile enterprises

· many enterprises have in their production both technical and traditional items technical products too have to comply with high aesthetical requirements, while traditional products must have well defined technical performances.

As for traditional textiles, also in the case of technical textiles there is a close link between the economical situation and the consumption volumes, but it differs according to the sector.

For instance, the trend of the transport sector conditions considerably the consumption of textiles for automotive applications (air bags, safety belts, panels and seat covers), just as the trend of avionics conditions the consumption of composites.

In other cases, on the contrary, technical textiles are anyway expanding, e.g. in the sectors related to ecology, health and wellbeing. Here trends remain even under difficult economic situations: in fact some values have become for certain reasons irremissible. The following tables show the fibre consumption for technical textiles in the major countries, the percentages of used fibers, the processes employed, the products and the market shares of each type of technical textile.

Read more...

Automated systems for material handling

The automated systems have been installed in the spinning mill whenever the price/performance ratio was profitable. Automatic can changing devices on cards and drawing frames have become standard, as well as the automated doffing systems on roving frames and on spinning frames.

As to the linkages between the various machines and to the material handling, following systems gained ground:

· linkage between lap winder and combing machine, for lap transport

· transport system for the roving bobbin with bobbin change by six or three units. An overhead trolley removes the bobbins produced by the roving frame, in a number corresponding to a sixth of the machine spindles and conveys them to an overhead store-room situated in front of the spinning frame. With same system the empty tubes are removed from the spinning frame and brought to the roving frame.

· robotized systems for unloading the bobbins from the open-end spinning machines and from the winders and their loading on pin trolleys or on pallets. These last, as soon as full of cones, are wrapped with a polyethylene sheet , weighed and labelled. These equipments can be placed at the end of the machine or in fixed positions fed by a bobbin transport system.

Read more...

Environment technology in Textile Spinning

Air conditioning, waste recovery, dusty air control, noise abatement, are all essential conditions to optimize product quality and working environment.

The air-conditioning plants for textile mills are based on cooling through evaporation and
have as their target to keep temperature and relative humidity constant in the various

production departments. These two parameters are essential for a successful running of the machines in all departments.

The air in the various departments is changed 20-30 times per hour, using suitable fans. The air is filtered, cooled and humidified and conveyed back to the working rooms. The plants have generally modular structure and are adjusted to the requirements of the single department.

Cotton processing causes the emission of large quantities of dust.

The machines are maintained clean through suction systems integrated in the machines, as in the case of cards and drawing frames.

On roving frames and spinning machines cleaning systems running on trolleys along the machines (travelling cleaners) are used which, through appropriate air blowing and suction phases keep machines and floor clean.

A particularly important role is played by the filtering systems, which are suited to the kind of dust originating in the different departments.

The spinning mills are also provided with waste recovery systems, which separate the single types of waste depending on the machines originating them, as they can be reused in different forms.

Read more...

Artificial fibres

As already mentioned in the introduction, the increase in world population (from 3 billions in 1960 to over 6 billions in the year 2000) and its growing needs made it necessary to integrate the production of natural fibres with those of man-made fibres ; these last expanded altogether at higher rates than natural fibres.

Moreover this fact permitted to countries lacking in natural raw materials to develop an important textile industry and to extend their application field (just think of the countless blending possibilities of natural with man-made fibres).

The exact product definition of artificial fibres (quite often referred to as ″cellulosics″) originates from the fact that they originate from a raw material which, though fibrous in nature, cannot be used directly by the textile industry and is therefore properly ″reclaimed″ through technical processes or ″expedients″.

Silk is the queen fibre that served as a model for the development of artificial silk, which took place at the turn of the 19^th century thanks to the invention of Count Hilaire de Chardonnet who applied for the first patent covering a ″textile material similar to silk″. Silk was also the model for the chemist Max Fremery who, in co-operation with the engineer Johannes Urban, succeeded in 1891 in dissolving cotton's natural cellulose in cuprammonium and thus obtained a filament for electric bulbs with better performances and much longer life than the filament used until then. Later on, having realized that by stretching the filament they could obtain a much finer yarn suitable for the textile sector, they started the production of viscose.

The artificial silk by the cuprammonium process was successively produced and bore the trademark Bemberg. The raw material of the Bemberg yarn are the linters, which are filaments of pure cellulose covering the cotton seeds and which are used in the production of some rayon types.

At the same time a process was developed, by which cellulose was converted to the liquid state through a solution of diluted caustic soda. This principle was successively named ″viscose process″.

Viscose too has a natural origin as it is derived from the cellulose of trees, which are specially grown for this purpose. It takes 22 years to a tree (generally pine tree) to reach the inner structure and the maturity which are decisive for the future quality of viscose. 100 years after the discovery of viscose, its production, in particular filament yarn production, remains still rather complex and time-consuming; in fact 30 days are necessary to obtain viscose from the cellulose sheet.

With the advent and development of synthetic fibres, the production curve of the artificial fibres have gradually levelled out, so that already in 1970 they were surpassed by synthetics. In fact in 1970 3.6 million tons of artificial fibres were produced, compared to 4.8 of synthetics. In 1998 the output of artificial fibres amounted to 2.8 million tons against 25 million tons of synthetics; therefore artificial fibres account today for less than

10% of the total production of man-made fibres. The Italian production of artificial fibres in 1998 amounted to about 30,000 tons; our country does not produce viscose staple.

As a matter of fact, in the last few years there has been a certain revival of the interest in viscose, especially as a filament yarn, which application fields extended from the traditional and highly appreciated linings to apparel and furnishings. However the viscose producers proceeded cautiously in new investments to cope with the increased demand, since these plants often use old technologies and have to tackle serious environmental problems. On the other hand, as regards staple fibre, new processes have been developed. They are solvent processes : one for Tencel viscose fibre produced in the U.S.A. by an English company, and the other for Lyocell fibres produced in Austria by a process in which cellulose is dissolved in N-methyl-morpholine oxide (NMMO) and water.

Well established is the high wet module viscose fibre, known as modal fibre, which is often used in blend with other fibres. A 1.0 dtex micro-version of this type of staple has been recently introduced. On the market there are also types of flame resistant viscose staple, which can be used in blend with other fibres to provide textile items with fireproof properties. We also wish to mention the extra-bright silky acetate and triacetate yarns derived from cellulose acetate. After spinning, also acetate can be subjected to the regular textile operations, as twisting, texturing, warping and sizing.

Read more...

Spinning

Learning the differences

The act or processing of converting staple or short lengths of fiber into continuous yarns.
Dictionary.com

*Ring Spinning
*Compact
*Open End
*Air jet

Yarn count ranges: 6’s to 250’s
Fibers: (1) Long (2) Fine (3) Strong


Yarn count range: 6’s to 250+
Fibers: (1) Long (2) Fine (3) short



• Very good pilling values and durability
(Pilling (Martindale) improved by 1.0 to 1.5 grades)
· Less surface hairiness, clear mesh structure
· Excellent evenness of knit fabrics
· Less fiber accumulations knitted into the fabric
· Luster
· Great alternative to plied yarns
· Less energy
· Softerthan plied yarns
· More economical than plied yarns

Open End - Schlafhorst

Open End - Rieter

Typical yarn count range: 6’s to 30’s


Open End Spinning

Murata Vortex


Spinning Efficiency and Endsdown:

Key Fiber Properties by the order of importance:

Energy Comparison
Energy Savings
Yarn Count : Ne40 (15/1tex) Combed cotton 100% for weaving
Production volume : 265kg/h (580Ib/h)

Do all yarns within the same spinning system require
the same type and quality of fibers?


DifferentYarn Counts Require
Different Fiber Indexes


Is Cotton just Cotton or a Different Cotton can Make a World of Difference?
Different Cotton can Result in substantial difference in Quality and cost

There are literally hundreds of variables in the spinning process which influence the outcome of fabric and garments.
Where is the source of fiber?
Do you have a relationship with the fiber producer and spinner?
What are the parameters in which the spinner purchases the fiber?
Does the fiber perform to expectations in relation to yarn count and fabric properties?
How is my garment impacted by fiber cost?
Do you have a relationship with the machine manufacturer?
What are the machine’s unique features?
Does the manufacturer of the machines offer excellent service, adequate training, and able
to respond quickly to parts and repair needs?
Is the spinner willing to partner with you and your the supply chain to improve the quality
and performance of fabrics?
Same goes with the machinery manufacturer?
Will your fabric supplier be open to the idea of you stating the spinner you want to use?
■ There may be bonds which need to be broken for this to happen..
• Dr. Yehia El-Moga hzy,Au burn University
■ yehiae@eng.auburn.edu
· Rob Beal, Oerlikon
■ rob.beals@oerlikon.com
· Mark Lingerfelt, Muratec
■ mlingerfelt@muratec-usa.com
· Hans Rothen, Rieter
■ Hans.rothen@rieter.com

Read more...