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Warp winding

The winding process involves transferring yarn from a smaller package to a larger package. There are two main objectives - to convert a smaller package into a larger package containing a long length of yarn, and to remove impurities from the yarn. The basic mechanisms of the winding process are unwinding, tensioning, yarn clearing, package building, and lubrication. Tensioning devices like multiplicative, additive, and disc types are used to provide the required winding tension. Yarn clearer devices remove faults from the yarn like thick and thin places. Package formation involves winding the yarn around the package using either a spindle or drum winder to build the package.

Engineering◦
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By Robel L. Department of Textile Technology Winding Process
2 Winding  Winding is the process of transferring yarn or thread from one type of package to another to type of package.
Objectives of winding (i) To convert a smaller package into a larger package containing a sufficiently long length of yarn. (ii) To remove the impurities such as weak places, snarls, slubs, thick places, etc from the yarn. 3
Technical Requirements of Winding Process  The physical and mechanical properties of the yarn should not be impaired.  Package should be built to ensure easy running off during warping at high speed.  The package should contain maximum length of yarn. 4
Cont.… The yarn ends should be tied with strong knots of correct structure easily passing at subsequent processing. The process should remove the objectionable fault. Yarn wastes must be as small as possible. The yarn tension should be regular and ensure constant winding condition
Based on the operation of the machine and the equipment flexibility, winding machines can be classified as (i) Non automatic winder (ii) Automatic winder 6
Basic Mechanisms of Warp Winding Process 7
The Basic mechanisms of warp winding process are: Unwinding. Tensioning. Yarn clearing. Package built.  Lubrication 8
1. Unwinding Factors affecting yarn tension by Grishin 9
 As the yarn is unwound from the package at high speed, centrifugal force causes it to follow a curved path(ballooning).  If balloon size increases tension on the yarn will increase and it will create contact with the m/c parts, this leads to yarn breakage.  Therefore, unwinding accelerator (anti-balloon device) should be used.  The anti-balloon device decreases the tension by having more number of loops. So we can go for high unwinding speed.  When 75% of the package unwinds from the spinning cop, tension of yarn will be increased considerably. 10
2. Tensioning  The needs for tensioning are: It gives required winding density. It gives suitable tension to the yarn.  It facilitates winding. It aids to remove weak yarns 11
Cntd… Tensioning devises can be classified in to four groups: (I) Multiplicative type (Post type or Capstan) (II) Additive type (III) Disc type (Combination of additive & multiplicative type) (IV) Automatic tensioner 12
Multiplicative type (Post type or Capstan) It is simplest form of yarn tensioner. In this methods, the yarn is passed around fixed posts. 13 0 T  e T T i  0
Additive type In this device, a dead weight or spring is used to give increment of tension. The yarn is passed through the middle of the surfaces in contact. The force is applied from above to give suitable tension to the yarn. 14
Disc type (Combination of additive & multiplicative type) 15
Automatic tensioner  This is a special type of tensioner which is able to control yarn tensioner automatically.  The device is arranged so that when measured yarn is too high, the pressure in the disc region is related to bring the tension back to its proper level. 16
3.Yarn Clearing/slub catcher  Yarn clearer or slub catcher is a device which is used to remove yarn faults in order to improve yarn quality and weaving efficiency. Faults removed by yarn clearer:  Thick & thin places in the yarn.  Slubs & neps.  Loose fiber.  Foreign matters. 17
Type of Yarn clearer Yarn clearer can be grouped in to: i. Mechanical clearer ii. Electromechanical clearer iii. Electronic clearer  Capacitance type  Photoelectric type 18
Cntd…  So every yarn break should be replaced with either knot or splice.  Knots – fastening made by tying a pieces of yarn.  Splice – joint of yarn ends by means of pneumatic or mechanical i.e pre-opening or untwisting followed by intermingling and twisting. 19
4.Package Formation  During winding the yarn undergoes two motions.  It is wound around the package by the package drive and  It is given a lateral motion to cover the package by the traverse mechanism. There are two ways to drive the yarn take up package. 1. Spindle winder (by direct drive to the package spindle with constant and variable speed)  It is important that the yarn be wound under as uniform tension as possible. 2. Drum winder (by surface contact) 20
i. Direct package driving at constant RPM/Speed.  In this system, the yarn package is placed on a spindle and the spindle gets motion by motor and gearing system. So the package gets a constant angular speed and here yarn take up rate is directly proportional to the package diameter. In spindle drive winders the tension is unequal throughout the package ,so a variable speed winder is used. 21
ii. Directly package driving at variable rpm/speed 22  In this methods, yarn package is driving directly at varying speed  To give constant yarn speed it is necessary to cause the rotational speed to vary inversely with package radius.
2.Drum winder (by surface contact) The drum is driven or rotated by the motor and machine gears and , when it rotates the package also rotates in reverse direction at a constant speed through friction, by contact with a driven drum. 23  In this system, the yarn package is placed with a surface contact of drum or roller.
5. Yarn Lubrication  Lubricants are used for reduction of friction.  A lubricant (wax) is applied for knitting yarn and weft yarn because the level of twist is low.  In winding of warp yarn, lubricants are not used. 24
Winding defects If patches are formed on the yarn. If winding speed is incorrect. Variation of yarn tension. If packages are dirty. Incorrect shape of yarn package. Too much knots in the yarn. Excessive full bobbin. Piecing up. Over lapping Two end winding
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