Weaving preparatory ProcessThere are three main steps of weaving preparatory process. 1. Winding 2. Warping 3. Sizing Flow chart of weaving preparatory process Winding • Transferring yarn from one type of package to other which is more suitable for subsequent process. • Transferring a number of yarns from a creel of single end packages, forming a parallel sheet on to a beam • Application of size material on the warp sheet, to induce desired properties Warping Sizing Winding Winding is a process in which yarn from ring bobbins are wound into convenient form of package. Transferring a yarn from one type of package, more suitable for subsequent process is also called winding. It occurs both in spinning & weaving. Main objectives of winding include: Increase package size according to the requirement of subsequent process Clearing yarn defects like slub, thick and thin places, neps, etc. Package dying Doubling Winding rate Winding rate is the speed at which the yarn is wound on package surface. In case of parallel package; traverse is very slow, so winding rate is approximately equal to the surface speed. 1 Production of Winding Machine Production of winding machine can be calculated by the following formula: Flow chart of Yarn Passage Through winding machine: Magazine Stop Motion Splicer Baloon Breaker Waxing Cradle Pre Cleaner Tension Device Drum Warping Warping is the process of transferring a number of yarns from a creel of single end packages, forming a parallel sheet on to a beam. The main objectives of warping are: To get the required number of ends as per set calculation. To get the required length of yarn on each beam of the set. To wind a specific type of package required by subsequent process. High speed Warping Sectional Warping Ball Warping Draw Warping 2 Types of Warping Machines 1. High speed Warping: In direct warping, the yarns are withdrawn from the single-end yarn packages on the creel and directly wound on a beam. 2. Sectional Warping: Sectional warping is a two stage machine method of preparing a warp on a beam, mostly used for yarn dyed fabrics. 3. Ball Warping: Ball warping is the process in which warping is performed in rope form onto balls. A ball warped beam is prepared for subsequent process. It is suitable for denim fabric manufacturing, involving rope dyeing process. 4. Draw Warping: Draw warping is combining the drawing of filament yarns with heat setting and warping process to achieve uniform stretching and heating for improved dye uniformity, end to end. It is used for weaving of thermoplastic yarns. Flow chart of Yarn Passage through Warping Machine Creel Warp sheet on to comb Guide Roller Spindles Headstock Warping Beam Tension Rods Stop motion sensor Pressing Drum 3 Sizing The weaving requires warp yarn to be strong, smooth and elastic to a certain degree. To achieve these properties, protective coating of a film forming agent is applied to the warp yarns prior to weaving. The application of size material on the warp sheet, to induce the desired properties is called slashing or sizing. Sizing is to produce Quality Fabric economically and efficiently. Objectives The main objectives of sizing are as follows: To get the required number of ends To increase the strength of yarn To cover the hairiness of yarn To maintain flexibility in yarn To make yarn surface smooth and pliable. Parameters Affecting Performance of Sized Yarn Parameters affecting performance of warp yarns during weaving include: Yarn Type: Staple, filament, ring, open end, comber, carded, etc. Material: cotton, viscose, polyester, etc Quality: Hairiness, thick and thin places, etc Sizing Machine: pre wetting, cylinder or hot air drying, etc Size recipe: Starch, PVA, CMC, etc Size pick up: more or less, core sized, surface sized Loom type: shuttle, air jet, rapier, etc Weave: plain, twill, satin Loom RPM: slow or high Personnel: trained properly or not Handling: machine speed, cylinder temp, etc Adjustment: squeezing pressure, moisture, etc 4 Flow chart of Yarn Passage through Sizing Machine Creel Mini Drying Cylinder Drying Cylinder Warp Sheet Squeeze Roller Waxing Device Size Box Immersion Roller Splitting Zone Press Trolley Measuring Roller Pendulum Roller Headstock Weavers Beam Feeding Roller Press Roller Comb Guide Roller 5