By: Shivendra Parmar and Tanveer Malik
Mankind knows textiles by generations. On a broad outlook it appears that textiles have no application other than apparel purposes. But as a matter of fact, there are non-apparel uses of textiles such as technical applications.
� Wondering what automotive textiles mean?
Automotive textile is that part of textile which is used in accordance with the vehicles i. e. it is widely used in automotive industry right from light weight vehicles to a heavy truck or duty vehicles.
Automotive textile is an integral aspect of technical textile. Since it cannot be classified in apparel textile, it is more of a techno mechanical application of textile. Industrial textiles are widely used in transportation vehicles and systems including cars, trains, buses, airplanes and marine vehicles. Approximately 50 square yards of textile material is used in an average car for interior trim (seating areas headliners, side panels, carpets and trunk, lining, tires, filters, belts hoses, airbags etc.)
Automobile textiles, which are non apparel textiles, are widely used in vehicles like cars, trains, buses, aircrafts and marine vehicles. Hence, the term automobile textile means all type of textile components e.g. fibers, filaments, yarns and the fabric used in automobiles.
Nearly two third of the automobile textiles are for interior trim, i.e. seat cover, carpets and roof and door liners. The rest is utilized to reinforce tyres, hoses, safety belts, air bags, etc.
It is projected that nearly 45 square meters of textile material is utilized in a car for interior trim (seating area, headlines, side panel, carpet and trunk). According to a survey, the percentage of textile in a motor car amounts to 2 per cent of the overall weight of a car. Apart from this, visible textile components, eliminating hidden components such as in tyres and composites, hoses and filters; amount to 10-11 kg per vehicle in absolute terms. Industrial textiles are largely utilized in vehicles and systems including cars, buses, trains, air crafts and marine vehicles.
Fibers used in various components:
The general classification and description of automotive textiles can be summarized as:
The volume of upholstery varies by region since manufacturers from different regions may prefer different styles of vehicle interiors. Both woven manufacture of automotive upholstery. An average of 5-6 m2 of fabric is used in cars for upholstery. Modern designers are trying to give sporty or elegant look to the car interiors.
Carpet is an important part of the automotive interior. Carpets must withstand temperature extremes. Needle-felt carpets, tufted cut-pile carpets are generally used. Major car producers are using tufted cut-pile carpets in their cars. Carpets usually have a rubberized backing.
Pre-Assembled Interior Components
Door kick panels, boot linings roof linings, parcel shelves and insulation (heat, sound, vibration etc.) materials are important examples for pre-assembled interior components. Coated laminated needle-punched non-woven and warp knits are the main materials used for the category.
The textile material in a type is used mainly for reinforcement. Textile materials such as viscose, glass and steel cords provide dimensional stability as well as reinforcement. Dimensional stability is an essential requirement for tyres. Strength is provided to tyres mainly by the web of fibres that lies with the body of the tyre called �Carcass�.
Due to governmental pressure and legislation, safety device have become a growing market for automotive textile. Seat belts and air begs are commonly used for safety in automotives. The seat belts control the forward movement of the wearers in the controlled manner during sudden stoppage of the vehicle. About 1 Kg of textile fiber per car is consumed in seat belts. An airbags is an automatic safety restraint system that has gained significance within the last decade. Airbag is not an alternative to seat belt but a supplement. Seat belt provides a protection regardless direction of collision but air begs provide protection against head on collision.
Filters And Engine Compartment Items
Hoses, belts and linen are important components car engine which are reinforced with textile materials. Automotive filters are largely made of textiles. Some example of the filters used in automotive are largely made of textiles. Some examples of the filter are air filter and oil filter. The function of these filters is to filter the fluid before it enters the engine because of delicate machine component may be destroyed if the dust particle enters into the engine.
One of the most traditional forms of automobile upholstery is plain woven cloth manufactured from air-jet textured and spun polyester. The textured yarns have good abrasion resistance because of their tight loop structure. The yarns contrived from �core and effect� components can produce fabric cover of very good quality. These types of yarns are based on a central yarn called the �core� which gives strength and stability to yarn.
In case of yarn dye route, the dyeing is carried out prior to weaving and in case of piece dye route, the dyeing is carried out at a later stage.
Carmakers are increasingly favoring the usage of weft knitted fabrics for upholstery. These fabrics are generally manufactured on circular knitting machines and process sequence follows yarn dye route.
Flat woven fabric is finished according to the yarn dye route. Finishing sequence for woven velvet upholstery is heat setting, brushing and then cropping.
The ranges of finishing operations carried out are wide and varied but the objective is to produce fabrics with functional qualities and good aesthetic appeal.
The formation of automotive upholstery involves the amalgamation of three layers i.e. face fabric, foam and backing material. The conventional method used for this purpose is �Flame laminate on.� But this process is environmentally unfriendly and some times the laminates lack porosity which affect the sound absorption and comfort. Hence, new technologies such as hot melt adhesive application are being introduced.
Hot melt adhesives are solvent-free adhesives, that are characteristically solid at temperatures below 180 degrees F (�F), are low viscosity fluids above 180�F, and rapidly set upon cooling. The development of hot melt adhesive technology stemmed from the previous use of molten wax for bonding. When this method no longer satisfied performance needs, 100 percent thermoplastic systems were introduced. Today, hot melt adhesives are used in a variety of manufacturing processes, including bookbinding, product assembly, and box and carton heat sealing.
There are a number of hot melt adhesives in use, with the most common being those used for hot melt pressure sensitive adhesive applications:
� ethylene vinyl acetate (EVA) copolymers, compatible with paraffin, the original hot melt;
� styrene-isoprene-styrene (SIS) copolymers;
� styrene-butadiene-styrene (SBS) copolymers;
� ethylene ethyl acrylate copolymers (EEA); and
� Polyurethane reactive (PUR).
Generally, these polymers do not exhibit the full range of performance characteristics required for an end product by themselves. Thus, "a variety of tackifying resins, waxes, antioxidants, plasticizers, and other materials are added to the adhesive formulation to enhance the polymer performance."
The latest hot melt adhesive advance is the PUR adhesive, which is a 100 percent solid, one-component urethane prepolymer that "behaves like a standard hot melt until it reacts with moisture to crosslink or chain extend, forming a new polyurethane polymer." By curing the polymer in this way, PURs have performance characteristics that are more enhanced than those of standard hot melts. Unlike many of the other hot melts, which require a slot die or roll coater, PURs are applied to a substrate as a dot or a thin glue line, set in seconds, and are structurally rigid in minutes, following a final set. These adhesives have been accepted in many manufacturing industries, where they can be applied in small bond points to eliminate use of mechanical fasteners, such as staples, screws, rivets, clips, snaps, nails or stitching.
Hot melt adhesives form a strong bond quickly simply by cooling, are compatible with most materials, and are clean and easy to handle. ) In general, hot melt adhesives are less water sensitive than other thermoplastic polymers, and are unaffected by water, moisture, or humidity, although if applied to a damp or wet surface the bonding may be poor. Hot melts can be formulated to increase their water sensitivity, as when used for stamps, envelopes and paper products that are to be recycled.
Hot melt adhesives have some limitations that must be recognized. Hot melts cannot be used with heat sensitive substrates; the adhesive bonds lose strength at high temperatures; chemical resistance may be lacking with some types of hot melts; and exposure to high temperature environments can cause the adhesive to melt. Consequently, hot melt adhesives are inappropriate in situations where these limitations cannot be avoided. For example, hot melts should not be used on a substrate that would be near a heat source, such as a kitchen cabinet that would be placed near an oven. However, innovations in hot melts are removing some of these limitations: PURs are resistant to heat once they are cured, and could be used on substrates subsequently exposed to heat.
Carpets are manufactured either by tufting or needle felting. Carpets made by tufting are based upon a supportive backing which is used as a base to accept the pile yarns which becomes the uppermost surface.
Carpet backing is usually spun bonded and is made by an integrated process in which polymer chips are melted and filaments are extracted through a die. Mainly polyester is used in Making this carpet backing whereas a blend of nylon and polyester is used in some occasions. But during recent times polypropylene is assuming great importance considering the recyclability.
The process of needling has got the advantages of more productivity at relatively low cost. But carpets produced by needling cannot be used to cover sharp counters especially foot areas and transmission tunnels. Superior needled material has a good filling which is determined by the amount of vertically oriented fibres at a given stitch density.
Generally, carpets are made by the combination of a variety of functional layers into a single unit and these types of carpets are very popular. A layer of adhesive is applied on these carpets during the initial stages stiffen the whole carpet structure and some cases specially formulated backing compounds are used to impart unique functional properties. A heavy mass layer that acts as soundproof materials is common to all automobile carpets. Carpet that has been finished is sent to a modeling station where it is pressed to deep draw mould to form it with appropriate dimensions. In European market visco-elastic polyurethane foam is used for backing while in American market, cotton fibre pad is used. The trend in USA is towards more molded polyurethane foam due to its superior acoustical and physical properties.
Now a days wearing of seat belt is become compulsory for drives and front seat passengers. About 1 kg of textile fibre per car is consumed in seat belts. Seat Belts need to be as soft and flexible as possible along the length direction but as rigid as possible in the width direction so they can slide easily through buckles and to retract smoothly into housing. The edges must be scuff resistant but not unpleasantly hard and the material must be resistant to UV degradation and retain its strength for the life of the car- otherwise it must be replaced some of the first seat belts were made from polyester because of its superior resistance to UV degradation.
Now days, the seat belts are being woven on shuttle less needle looms which can deliver up to 1000 picks per minute. Whereas, previously, the weaving used to be carried out on shuttle looms which were capable of delivering upto 200 weft insertions per minute from small weft suppliers, which frequently needed replenishing. Seat belt webbing is generally woven according to 2x2 twill design. The twill weave is preferred because warp threads lie parallel to the face and back of the webbing and as a result, the material has a high warp ways strength and low elongation.
Prospects and problems of the automotive industry are known to the manufacturers and several deliberations to review the industry have been taking place. Some of the latest trends discussed below:
There are many textile components in a tyre such as casting belt breaker faric, bead wrapping fabric, chafer fabric, filler fabric, tyre cord fabric etc. nylon 6 and nylon 6,6 tyre yarns is used widely with nylon 6 being the major one. The fibres generally used for tyre cords are high tenacity filament yarns of nylon 6, nylon 6,6, polyester and viscose. In the past plied cotton yarn was used for the manufacture as tyre cord fabric as it had natural compatibility towards rubber fibres having high modulus such as Kevlar glass or steel are being used in manufacturer of cords compressing the breaker or belt layer viscose is the commonly used fibre in redial ply tyre casing. Carbon fires are also finding application in the form of reinforcing material.
Stringent government legislation, consumer pressures are the driving forces for the massive growth and development of the air bags. In USA, the market for air bags is very huge and it is still in a growing stage in case of Japan and Western Europe. The requirement for an air bag material is high strength, resistance to ageing and abrasion, compatibility with coatings and good impact absorption. Hence nylon 6, is the mostly used material for the construction of air bags. Polyester is rarely used for this purpose and this trend seems to continue.
How An Airbag Works?
Airbags inflate, or deploy, quickly -- faster than the blink of an eye. Imagine taking one second and splitting it into one thousand parts. In the first 15 to 20 milliseconds, air bag sensors detect the crash and then send an electrical signal to fire the airbags.
Typically a squib, which is a small explosive device, ignites a propellant, usually sodium azide. The azide burns with tremendous speed, generating nitrogen, which inflates the airbags. Within 45 to 55 milliseconds the airbag is supposed to be fully inflated. Within 75 to 80 milliseconds, the airbag is deflated and the event is over.
Airbags may save lives and guard against severe injuries in high speed collisions, if designed properly. However, the speed with which airbags inflate generates tremendous forces. Passengers in the way of an improperly designed airbag can be killed or significantly injured. Unnecessary injuries also occur when airbags inflate in relatively minor crashes when they're not needed.
In the past, the air bags were coated by Neoprene. Generally, coated air bags are preferred for driver�s seat and uncoated air bags for side seats. Recently, silicon coated and uncoated air bags have become very popular due to advantages such as extended service life, adaptation to heavy duty vehicles, reduced module size, cost reduction, improved recylability.
The seat is probably the most important item in the car interior. It is the first thing the customer seed when the car door is opened and he or she will probably instinctively touch it. Textiles have become by for the most widely used material in seat coverings and are beginning to be used in other areas of the seat in place of polyurethane foam. They are also used in a number of specialist cases in place of metal springs and actual seat pan and seat back. Now a day�s polyester is very popular material for making seats, like polyester in the face fabric, Polyester non-woven in the cover laminate and polyester non-woven also in the seat squab and Cashion.
The traditional method of seat making involves cutting and sewing of panels of the seat cover laminate (face fabric/foam/ scrim) into a cover, which is then pulled over the squab (seat back) and Cashion (seat bottom) , and then fixed in place using a variety of clips and fastenings. This process is both time consuming and cumbersome. Hence several attempts have been made over the years to find better ways using a variety of techniques. Now a days three dimension seat covers are the very good. A seat cover comprises a knitting of a three-dimensional structure conforming in its external shape to that of a seat and including at least main portions, side portions and welt portions integrally knit into a one-piece form. The knitting further includes integrally knit portions covering overhang portions and corner portions of the seat and/or rear and bottom portions of a front back of the seat.
At one time the headliner was simply a covering for the metal roof inside the car and consisted of a piece of fabric, PVC or same other material sometimes simply �slung�. i.e. held in place only at a few points. Some important requirements of headliners are light weight, thin profile but rigid without any tendency to buckle, flex or vibrates, good dimensional stability, aesthetically pleasing and preferably with a soft touch.
The modern headliner is a multiple laminate of up to seven or more components all joined together. Each layer is there or a specific purpose either for aesthetics, to provides sound insulation, vibration clamping or to provide rigidity to the whole structure. The central layer is generally a layer of semi-rigid thermomouldable polyurethane foam. This layer is bounded to two layers of chapped fibre glass roving, one on each side. The layers of glass-roving help impart rigidity to the structure and noise reduction.
Attached to the side facing inwards is the decorative material, a non-woven polyester scrim is usually attached to the other side. All layers are joined together by action of the hot-melt adhesives in a flat-bed laminator, taking care neither to damage the aesthetics of the decorative material nor to reduce the thickness of the centre core.
Textiles For Noise Control
Sound is propagated through the air and by vibration of the car body and there are three basic mechanism for reducing it, by absorption, by clamping and thirdly by isolation or insulation. In general thick piece of material will absorb more sound than a thinner piece of the same material. There are number of layers of material and permutations of layers of material used in noise and vibration damping. These layers are,
1. Top decorative layer: - Tufted BCF Nylon or needle punched polyester or polypropylene- Back, acrylic ladere.
2. Thermoforming layer: - Polyethylene powder, moldable fibre EVA or a further thick layer of compounded SBR (styrene-butadiene rubbers) later.
3. Caustic layers: - �Heavy layers� of EPDM, Shoddy fibres or polyurethane foam.
These materials generally have to be fitted in small pieces, which is time consuming and produces an insulation performance which is interior to that of a continuous layer. In some vehicles this insulation layer is formed directly on the back of the pre-formed carpet it self by back injection moulding using polyurethane foam.
Cabin Air Filter
There are about a dozen different kinds of filter used in cars but only about half use textile materials. Paper is used in many applications such as the oil filter and carbure air filter, although non-wovens are used in some cars for the latter application. Dust diesel fumes and aromatic hydrocarbons can be even more damaging to health, hence filters are very much necessary.
The latest advanced filters combine both mechanical filtering through polypropylene non-woven electret fabric with adsorption by activated carbon. Filter fabric is arranged in a pleated form to provide maximum surface area with minimum airflow resistance. The adsorption and retention capacity of the filter for odors in a given air flow rate is a measure of the filters performance. The non-woven filter fabric it self must be strong when wet is odor-free resistant to micro-organisms and resistant to extremes of temperature. Allied signal recently announced a filter for both particles and odors, which uses a system that is based on micro-fibres and a special liquid absorber.
Textile materials are used in automobiles for interior trim and for ensuring comfort (e.g. seat covers, carpets, roof liners, and door liners) as well as for reinforcement (e.g. tyre) and filters. Textiles also offer weight reduction which in turn results in fuel economy.
Airbags help to save lives, but at times they can also be a source of serious injury. The search for a uniform smart airbag, which can perceive the size of the passenger or whether the seat is empty and react in that manner, is in progress. Such a 'smart' airbag will incorporate sensors to judge the weight, size and location of the car passengers and hence deploy more appropriately.
In addition, incorporated safety devices associated with the seat belt along with other safety items, particularly for child passengers, are under development. The trend towards uncoated fabrics is anticipated to continue and so is the improved trend towards more airbags per car and full-size bags. There is also a technical challenge of producing the bag by using more rational techniques and related specifications made by the automotive industry.
First of all we would like to express profound gratitude to the management of the institute, Administrative Officer Shri R.C. Parmar Principal Dr.Ing. V.P.Singh, and Advisor Prof. Dr.H.V.S. Murthy and Head of the department Prof. Dr. Prabhakar Bhat for giving encouragement and guidance to write a paper on APPLICATION OF TEXTILES IN AUTOMOBILE
The authors are Lecturers in the Department of Textile Technology, Shri Vaishnav Institute of Technology and Science, Baroli (Indore-Sanwer Road), Distt: Indore (M.P), India, Pin-453331
E-mail: firstname.lastname@example.org, email@example.com
To read more articles on Textile, Fashion, Apparel, Technology, Retail and General please visit www.fibre2fashion.com/industry-article
To promote your company, product and services via promotional article, follow this link: http://www.fibre2fashion.com/services/featrued-article/featured_article.asp