Research On The Dimensional Properties Of Seamless Knitted Underwaer

Seamless knitted underwear is a kind of almost fully-fashioned fabric knitted on the special equipment. Compared with traditional knitting garments, it is more comfortable and better fit because of less or none sewing. Therefore, seamless knitted fabric is very popular and it can be sure that it will have a bright prospect. But the problem with size control of seamless knitted fabric is one of the main reasons that hinder its development. So far, the design and production of seamless knitted fabric still depends on the experience of proofing technicians to test knitting again and again, then adjust the yarn specification, fabric stitch or knitting technology according In the testing results, which is both time and material wasting. So investigating on the relationship between seamless knitted fabric dimensions and yarn properties, fabric stitch and knitting parameters can be of great significance.The paper firstly had a brief introductioru of the structure of seamless knitting machine SM8-TOP1and the knitting principle of some main common used fabric stitches. Traditional seamless knitted fabrics are usually made of nylon spandex core-spun yarn, cotton or polyester. Then a design software which is commonly used in seamless knitted fabric designing was presented following, including mapping software PHOTON and programming software QUASARS.Seamless knitted fabrics are directly made of yarns, so the yarn properties especially mechanical properties and thermal properties have a great influence on the fabric dimensional characteristics. The mechanical and thermal behavior of nylon spandex core-spun yarn, polyester filament yarn and polyester/cotton yarn were tested respectively in this paper, and qualitative analysis concerning their impacts on fabric dimension was made according to the testing results.To find out the quantitative relation between seamless knitted fabric dimension and those factors that could be controlled during the production, nylon spandex core-spun yarn was taken as ground yarn, paired with plating yarn including polyester filament and polyester/cotton yarn separately to knit cylindrical fabrics of single stitch on SM8-TOP1, while changing the fabric stitch, sinking depth and the yarn tension corresponding. Through lots of experiments and regression analysis, several conclusions were drawn:the shrinkage rates of non-plain fabric dimension compared with plain fabric, the quantitative relations between fabric sizes after full relaxation and sinking depth of six different stitches, the impact extent of fabric size with the change of plating yarn tension.Scouring and dyeing are very important processes in the production of seamless knitted fabrics, which both have great influence on fabric size. To find out the dimensional changes of seamless knitted fabrics after scouring or dyeing, commonly used scouring and dyeing processing were chosen in this paper to conduct on fabrics which had been fully relaxed previously. Then their dimensions were measured after conditioning and the shrinkages were calculated. At last, tables that collected shrinkage rates of different yarns in different stitches after being scoured or dyed were obtained, so that in actual production of seamless knitted fabrics, optimal processing and the size control could be realized on the basis of these tables.