1. FABRIC STRUCTURE PROPERTIES OF AUTOMOTIVE SEAT FABRICS
Assoc. Prof. Dr. Fatma ÇEKEN, Gülşah PAMUK (MSc)
DOKUZ EYLUL UNIVERSITY ENGINEERING FACULTY
TEXTILE ENGINEERING DEPARTMENT, TURKEY
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Technical textiles are considered to be the fastest growing sector of textile market and 19% (10 million tones) of the total world fiber consumption is used in this field [5]. It’s estimated that this figure will rise to 14 million tones by the year As it seen table (1), transport sector takes the first place in main growing shields [2]. The automotive textile industry which uses 20 kg technical textiles for each of the 45 million cars produced every year in the world is the biggest technical textile employer [2] and it is estimated that every year more than 1 million tones textile is consumed for this market [3]. These textiles are air bags, floor and ceiling laminates door panels and seat cover fabrics.
Table-1: Technical textile markets by sector-world estimates: year 2005
Application
(‘000 tones) %
Automobiles, shipping, railways and aerospace
2,483 16
Filtration, cleaning and other industrial fabrics
2,344 17
Furniture, upholstery and floor
2,259
Hygiene and medical
1,652 12
Building and construction
1,266 9
Agriculture, horticulture and forestry
1,021 7
Technical components of shoes and clothing
824 6
Packaging
658 5
Geotextiles and civil engineering
574 4
Sports leisure
390 3
Environmental protection
305 2
Personal and property protection
215 1
Total
13,991
100 %
Developments in Technical Fabrics- Part 1
People spend more time in their cars with increased daily commuter distances to and from work, increased traffic density, more people work away from home and travel long distances by car at the weekends [2]. For this reason the automobile manufacturers not only improve the technical and mechanical primary functions of the automobile but also improve the secondary parts that appeal to the senses, such as seats, door panels, carpets etc and the importance of interior design is increasing as customer’s expectations rise. Seat covers is one of the most important factor for interior car design and for passenger’s comfort.
Seat covers should withstand till the end of automobile life, at least for a ten-year period. For this reason high performance fabrics especially high resistant to abrasion, crocking, pilling, flammability and UV besides tear strength, tensile strength and tensile extension are demanded. The main fiber types used for seat covers are polyester and acrylics. Polyester fibers that has good resistance to UV degradation, heat and chemical degradation, easy care characteristics, durability, low moisture absorbency, resilience and good dimensional stability takes the place of acrylics which has faster flammability speed and higher UV degradation [4]. For these reasons, polyester fabrics are ideal for automobile seat covers and approximately over than 90% of seat covers are made from these fibers [2].
The main fabric technologies used for seat covers are woven velour, jacquard woven, warp knit, warp knit pile sinker (Pol), warp knit double needle bar raschel velour, circular knit jacquard pile and spacers [5]. Figures 1, 2, 3 and 4 show these techniques.
Figure 3: Warp Knit Pile Sinker (Pol)
Figure 1: Woven Velour
Figure 4: Circular Knitting
Figure 2: Warp Knitting
When producing circular knit jacquard pile the fabric is knitted as a circular tube and after slitting into a flat sheet it is passed under a cropping machine which crops the tips of the loops leaving a vertical pile and this process causes a lot of waste due to cropping which makes these types of fabrics expensive despite this versatility its infinite designing and flexible properties ensured a significant place in the market. The warp knitted fabrics have a structure that can be controlled and specific level of stretch and recovery. The warp knitted structures have a big importance because of their capability of achieving a very wide range of surface textures and three-dimensional designs. The major limitation of warp knitted structures is their relatively limited capability to producing large area of color and design effects. Woven fabrics have limited stretch property compared to knitted fabrics. This characteristic makes a disadvantage for automotive seat fabrics and door panels both of which requires high elongation property [4]. Stretch polymers are used to eliminate this disadvantage. Especially in Japan, jacquard woven velour automotive seat fabrics are widely used [4]. Their 2% waste rate in cropping process is even lower when they’re compared to circular knit pile fabrics. Spacer fabrics are stuffed structures produced in double needle bar warp knitting and weft knitting machines. Although their major application is in footwear and too expensive for automotives, when used in seat covers, they provide temperature control, comfort and support.
REFERENCES
1. Anand, S. Developments In Technical Fabrics- Part I. Knitting International. 2000, July, p. 32–35
2. Anand S. In The Driving Seat-Part II. Knitting International, 2001, July, p. 54–57
3. Anand, S. Recent Advances In Knitting Technology And Knitting Structures For Technical Textiles Applications. ISTEK 2003 Proceedings, p. 97–113
4. Fung W., Hardcastle M. Textiles In Automotive Engineering. Woodhead Publishing Limited, England, 2001.
5. Hardcastle M. In The Driving Seat-Part I, Knitting International, 2001, July, p. 51–53