Project report prepared by, FAISAL AHMED ROLL NO.070023
Bangladeshi knitwear is exported to over 100 countries of the world and has passed the target of US$ 5.5 billion mark in its exports this fiscal year. Bangladesh is now the number three exporter of knitwear to the EU countries after China and Turkey and is gaining momentum due to its self-sufficienc y and competitive workforce and strength in backward linkage. Over a period of time the knitwear sector has gradually become almost self sufficient in fabric and yarn and this improvement has become possible because of the integrated growth of spinning factories in line with the growth of countrys stitching capacity and increased need for yarn and fabrics. As the exports have increased in the knitwear sector, the capacity of backward linkage has also gradually increased accordingly. The result is that local suppliers can provide 90% of the total fabric requirement of the sector. The growth of spinning mills has also been in step with the growth of knitwear exports. In 1993-94 the total number of spindles was 1.38 million that supplied 10.70 million Kg of yarn. In 2003-04 the number almost tripled to 3.77 million, which supply 239.00 million Kg of yarn. To date, the total investment in the backward linkage industry is more than US$ 2.00 billion. Bangladesh’s knitwear industry is growing at over 15% per annum.
• Spirality is a common problem in weft knitted fabric. It is the de- twisting tendency of yarn in the fabric. It appears in mostly in single jersey fabrics but in double jersey fabrics this level in about zero. The causes of formation of spirality in twistness in the yarn and increase it by using more number of needles and multifeeders machine so on. It can reduce in different ways but not remove from the fabrics.• Shrinkage is the dimensional change in length and width wise in the fabric. It mainly occurs for swelling of yarn. So, it appears more in cotton fabrics than synthetic fabrics. It can reduce the shrinkage by using stenter machine after dyeing and drying the fabric. Also, if the higher GSM/lower stitches length/lower twist fabric contains lower shrinkage of fabric.• For measuring the spirality and shrinkage at first we have done ISO-6330 washing then use ISO: 16322-2 for spirality and ISO- 5077 for shrinkage. And these are international standard of these measuring systems.
Shrinkage: A dimensional change resulting in a decrease in the length or width of specimen subjected to specified condition is known shrinkage.Spirality: If the wales of the knitted fabric are not perpendicular to the course and skew to the right or left Spirality occurs in the fabric. This creates serious problem, especially in the apparel industry.Yarn twist: Twist is the measures of the spiral turns given to a yarn in order to hold the constituent fibers or threads together. Amount twist i.e.TPI greatly influenced the fabric Spirality.Twist liveliness: The tendency of a yarn is to twist or untwist spontaneously. The direction of twist liveliness or torque S or Z twist change that takes place spontaneously when an end or hanging loop is allowed to rotate freely. Higher amount of twist leads high liveliness and creates fabric Spirality.Dry Relaxed State: The fabric moves to this state with time. The dry relaxed is restricted by fabric structure and fiber type. Only wool can attain this state.Wet Relaxed State: Static soak in water and dry flat. This state tight structure doesn’t always reach a true relaxed state. Only wool and silk can attain this state. Soak water with agitation or agitation in steam or static soak at selected temperature (below 900C)
RAW MATERIAL OF APS APPARALS LTD. Source of cotton yarn Local Imported Prime Winsome Youth G.T.N Nahid NZ Textile Shirin Acetone Techno Sudan Chandra Texlong Bengal NFK Rajastan Mondal Indosome Otto Metro Badsha Shah Fatulla
Spirality is a dimensional distortion in circular plain knitted fabrics. The wales or needle lines, should occupy a truly vertical line in the fabric and should always be right angles to the cross wise courses of stitches. This perpendicularity of wales to the courses is frequently, not the case and many times the wales may skew to the right or left forming an angle, which appears in the form of a twilled surface.
SHRINKAGE A dimensional change resulting in a decrease in the length or width of a specimen subjected to specified conditions is known shrinkage. Reduction in length and width of fabric induced by conditioning, wetting, steaming, chemical treatment, wet processing as in laundering, in chemical practice and in literature the following terms have been used to describe the shrinkage which occurs in testing procedure: Relaxation shrinkage, Felting shrinkage, Compressive shrinkage, Residual shrinkage.
CAUSES OF SPIRALITY: The residual torque or twist liveness. Count of yarn, Fabric structure, GSM Fabric Relaxation, No. of feeder. Twist direction, Machine rotation, Spinning system, Fabric finishing.
Average deflection length from the seam line = X Y= Sample length, Spirality% = Example: Average deflection, X = 2cm Sample length, Y = 50cm Spirality% = As per the experience of world renowned retailers in the globe, seam twisting / shape distortion / spirality greater than 6% in tops and shorts and 4% in skirts, pants, dresses, and sleepwear detracts from the appearance of the garment.
RELATION BETWEEN GSM & SHRINKAGE% FORPOLYESTER YARN IN DIFFERENT DRY CONDITIONS. 2.5 2sh 1.5ri 1nka 0.5 wg ie 0 s% Tumble Dry(120 GSM) Hang Dry (120GSM) Flat Dry (120GSM) ei -0.5nW -1id -1.5th -2 -2.5 single jersey fabric GSM (Polyester)
RELATION BETWEEN GSM & SHRINKAGE% OF DIFFERENT TYPESOF FABRICS (TUMBLE DRY) 2 1shr 0i PK(22O GSM) 1*1 Rib(220GSM) Interlock (220GSM)nk -1a wg ie -2 s% ein -3Wid -4th -5 -6
In finishing section fabric GSM, Spirality and shrinkage being controlled in various finishing machine such as squeezer, dryer, open & tube compactor and stenter. Some descriptions are given below: Squeezer: Textile materials such as knitted fabrics are usually extended in length wise direction due to tension specially in dyeing process. When the dyed fabrics are passed through the squeezer dia of the fabric can be controlled by adjusting the width of the spreader frame by controlling width wise shrinkage. Squeezer machine helps to remove water from the fabric. Specification: Name: squeezer machine. Brand: SANTAX Origin: Switzerland. Data: Squeezer
Fabric type Color GSM Machine speed Over feed Dia Dia+Single jersey Navy 180 20 +30% 60 +4Single jersey Dark red 160 20 25% 60 +4Single Lacoste Sky blue 150 20 20% 69 +4Double lacoste Avg(wood) 180 20 25% 66 +4Interlock black 210 20 18% 108 +5Flat back rib black 340 20 15% 75 +5
Fabric type Color GSM Line speed Compaction% diaSingle jersey Navy 180 40 8% +4Single jersey Dark red 160 40 6% +3Single Lacoste Sky blue 150 25 8% +3Double lacoste Avg(wood) 180 40 18% +5Interlock black 210 40 15% +8Flat back rib black 340 40 15% +2
Fabric type Color GSM Required dia Finished dia Finished GSM Shrinkage in Shrinkage in length wise width wiseSingle jersey Navy 180 60 61 178 -5% -4%Single jersey Dark red 160 60 61 155 -4% -2%Single Lacoste Sky blue 150 69 68 147 -3% -7%Double lacoste Avg(wood) 180 66 63 165 -7% -9%Interlock black 210 108 109 210 -2% -4%Flat back rib black 340 75 75 345 -4% -3%
CONCLUSION In general the angle of spirality values are decreasing, when the tightness factor values are getting tight in the all knitted fabric samples. In slack knitted fabric structures, the loop can easily find area to rotate so spirality is increasing. The spirality angle of the fabrics knitted with ring yarns are very high comparing with the fabrics knitted with open-end yarns. This shows the effect of the spiraled on twist liveliness. Because the twist liveliness of the ring yarns used in producing single jersey fabric is higher than the open-end yarns used in producing single jersey fabrics. Fabrics shrinkage depends on different fabric structure i.e; single jersey, rib, interlock and their derivatives. Yarn composition i.e; 100% cotton and polyester and synthetic yarn. More research and development is required to control the fabric specifications accurately. We could not able to execute the project work perfectly for limitations of time and lack of opportunity to examine the various tests in the factory.