Yarn Characteristics PDF

Yarn Characteristics  Definition of a YARN A yarn is a product of substantial length consisting of an assembly of fibres and/or filaments usually with twist used for interlacing in processes such as weaving, knitting, braiding and sewing. A yarn is fully characterized when the following featu...

Yarn Characteristics  Definition of a YARN A yarn is a product of substantial length consisting of an assembly of fibres and/or filaments usually with twist used for interlacing in processes such as weaving, knitting, braiding and sewing. A yarn is fully characterized when the following features are defined: Nature of the fibre: cotton, wool, synthetic etc. Count of the yarn: it defines the thickness/fineness of the yarn Twist: it defines both the level and direction of the twist Yarn structure & texture: spun/filament, single, ply, textured, novelty, core, bi-component, etc. Colour of the yarn: red, black, blue, mixed colours etc. Yarn Parameter 1: YARN COUNT Yarn Count The count of a yarn is an expression of its thickness/fineness (diameter). A yarn is a compressible (and fairly irregular) textile material and it is not always possible to measure its diameter/fineness accurately and precisely. So it is usually expressed in terms of the linear density or count. There are two count systems: Direct & Indirect System Direct System: Mass per unit Length; e.g. Tex and Denier - It is called the direct system because as the tex or denier value increases, the thickness of the yarn increases too. This system is applicable to yarn made from both natural fibres as well as synthetic fibres (filament and/or spun). Indirect System: Length per unit of Mass; the; e.g. English count (Ne) and Metric count (Nm). - It is called the indirect system because as the Ne or Nm value increases, the thickness of the yarn decreases. This system is usually applicable to yarn made from natural fibres such as cotton and wool.  Some Examples of Direct count systems Equivalent g/km g/9km g/10km mg/km kg/km No. of 14.4yds/lb g/10km No. of 14.4yds/lb Courtesy: textilelearner.blogspot.com  Direct Count Systems Yarn A having 20 tex means that 1 km of yarn A weighs 20 g. Yarn B having 40 tex means that 1 km of yarn B weighs 40 g. Which of the two yarns, A or B, is thicker? Yarn C having 20 denier means that 9 km of yarn C weighs 20 g. Yarn D having 40 denier means that 9 km of yarn D weighs 40 g. Which of the two yarns, C or D, is thicker? Conclusion: higher the Tex or Denier value of a yarn, the thicker the yarn is. QUESTION A synthetic multifilament yarn has a yarn count of 80 decitex. What does this mean? Some Examples of Indirect count systems Numbering system Units of length(l) Units of weight(W) Equivalent English cotton count (Ne) 840 yards (1 hank) 1 pound (lb.) No. of 840 yds/lb Metric count (Nm) 1000 meters / 1km 1 kg No. of 1 km/kg Woolen count (YSM) 256 yards 1 pound (lb.) No. of 256 yds/lb Worsted count (Nek) 560 yards 1 pound (lb.) No. of 560yds/lb Linen count (NeL) 300 yards 1 pound (lb.) No. of 300yds/lb French cotton count 1000 meters 500 grams No. of 1 km/500g Indirect Count Systems Yarn A having 20 Ne means that 20 x 840 yds of yarn A weighs 1 lb. Yarn B having 40 Ne means that 40 x 840 yds of yarn B weighs 1 lb. Which of the two yarns, A or B, is thicker? Yarn C having 20 Nm means that 20 km of the yarn C weighs 1kg. Yarn D having 40 Nm means that 40 km of the yarn D weighs 1kg. Which of the two yarns, C or D, is thicker? Conclusion: higher the Ne or Nm value of a yarn, the thinner the yarn is. Tutorial 1 Calculate the tex-count of nylon yarn, if the length of yarn is 20000 metres & its weight is 400 grams. The yarn of polyester filament weighing 50 grams in 6000 meter length, calculate the denier of the yarn The Conversion of Direct to Indirect count system and vice-versa Conversion Numerator = Direct Yarn Count Indirect Yarn Count Count Conversion Table Tutorial 2: Conversion from one count system to another The count of a yarn is given as 40 Ne, what is the count in Nm, tex and denier? Use the conversion table given. The count of another yarn is given as 20 tex, what is the count in Nm, Ne and denier? Use the conversion table given. Tutorial 3 The finished construction of a cotton woven fabric for shirting is given as follows: 45 x 30 / 40 x 40 Nm system 45 x 30 stands for 45 warp yarns and 30 weft yarns per cm. 40 x 40 stands for the count, in Nm, of the warp and weft yarns respectively. Assuming the yarn crimp is negligible, determine the mass per unit area of the finished fabric in g/m2.  Relationship between count and diameter of cotton spun yarn If the count of a yarn is doubled, say, from 40 tex to 80 tex. Is the diameter also doubled. Assuming same packing density? d in inch = 1/{28 × √(Ne)} or d in mm = 0.0037 × √(Tex) Can you express the relationship between the diameters of two yarns when the tex or Ne of one yarn is twice the other? Expression of Linear Density: Folded Yarn In the Direct tex system there are two possible ways of referring to folded yarns: Example 1: 40 tex x 2 indicates a yarn made from twisting together two 40 tex yarns. It does not take into account the yarn contraction when folding the two yarns together. Example 2: R 80 tex/2 indicates a yarn made from twisting two yarns together which results in a 2-ply yarn whose linear density is 80 tex. This type of designation may or may not take into account the yarn contraction when folding the two yarns together. The yarn contraction has to be specified. 110 x 60 (inch); (50/1, 100/2) Nm system meaning? Yarn contraction when folding the single yarns together Be aware that the two systems are not identical. Yarn contraction in length (during twisting of folded yarns) make the resultant count slightly higher than would be expected from the count of the single yarns. If the yarn contraction is 5% when twisting together two yarns of 80 tex each. What would be the resultant linear density of the two-ply yarn? We would normally expect the resultant two-ply yarn to have a linear density of R160/2 but due to yarn contraction, the actual linear density is: R [100/95]*160 tex R168 tex/2 The ‘increases’ of 8 tex is due to yarn contraction on twisting the two single yarns of 80 tex each; approximately 5% of 160 tex = 8 tex Another way of expressing it is as follows: Let the yarn count of the 2-ply yarn be 160 tex after folding. Since the yarn has contracted by 5%, the actual length would be 95% of its full length. 95% of full length corresponds to a count of 160 tex , so for 100% full length, the count would be 100/95*160 ~ 168 tex For indirect system, let’s say two ply 40s yarn; i.e. 40s/2; Without yarn contraction, the resultant count would be expressed as follows: 1/R = [1/40 + 1/40]; so R = 20 Ne With 5% yarn contraction, the count of the 2-ply yarn would be: R1= R*95/100 = 19 Ne So the resultant count would be R 19 Ne/2 What are the popular yarn counts for garment, shirts, tshirts, trousers etc.? Yarn counts are discrete numbers and the most popular ones are: 20s, 24s, 32s, 40s, 50s, 60s, 80s and 100s ( s is the British system and equivalent to Ne) Common counts for cotton yarns Yarn Counts for Apparel In general terms, fine count yarns range from 20 tex, or 20 g/ km, to less than 10 tex or 10 g/km. Medium-count yarns range from 20 to 50 tex whilst coarse count yarns range from 50 tex up to >300 tex. General descriptions for yarn counts: Yarn counts less than 15 tex are used in light weight shirting fabric or knits 20 to 40 tex yarn is used in underwear, t-shirts and singlets >50 tex yarn is used for trousers, denim and heavier outer layers. At >300 tex, yarn is used for bulky knits, very coarse fabric, e.g., blankets, and/or industrial fabrics. Summary In short the count of yarn is a numerical expression which defines its fineness or size of the yarn. It also expresses weather the yarn is thick or thin. According to the textile institute yarn count is a number which indicates the length per unit weight of the yarn or weight per unit length. It is an important yarn parameter/characteristic and determinant of fabric weight and thickness.