Singeing and shearing (Pre Treatment)


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Singeing and shearing (Pre Treatment)

  1. 1. 17-Jan-12 Pre Treatment: Introduction & Singeing, Shearing Aravin Prince Periyasamy Dept of Textiles, DKTE TEI, Ichalkaranji, MH, India aravinprince@gmail.comPreparation Definition  Preparation is the process of preparing fibers yarn, or fabric for subsequent steps such as Dyeing, Printing, Finishing and or special processes for apparel and non apparel end Uses.  Removal of impurities by physical and chemical method.2 1
  2. 2. 17-Jan-12Preparation Objective The aim of above process to produce a substrate that has…  Uniform extraction of impurities  Uniform standard of whiteness  Uniform swollen fibers to transport dyes and chemicals  Minimum fiber damage  Uniform residual moisture content.3 Preparation Process  These processes ensure that textiles have the right physical and chemical properties to enable them to be coloured or finished.  Examples Singeing, Desizing, Scouring, Bleaching, Heat- setting, Mercerization and etc.4 2
  3. 3. 17-Jan-125Sequence of Pre Treatment6 3
  4. 4. 17-Jan-12 2)flow Chart Of Pre Treatment Of Silk Fiber/Fabric73) Flow Chart Of Pre Treatment Of Wool Fiber/Fabric8 4
  5. 5. 17-Jan-124)Flow chart of pre treatment of Polyester/cotton fabric 9 Pre – Treatment Process Pre Treatment can be done in two different conditions there are Wet and Dry Conditions. Dry Condition To effect the removal of the Unwanted substances, there are two stages as follows  Pre-cleaning brushing  Cropping and Shearing 10 5
  6. 6. 17-Jan-12Cropping And ShearingDefinitionShearing is the process of cutting projecting fibers and yarns to give smooth and clean appearance by rising knives and blades.Objects To remove the projecting yarns and filaments from the surface of the fabric To give clean and smooth appearance to the fabric. To control pill formation.11 Shearing machines:  The shearing process is also referred to as cutting and cropping,  The general purpose of shearing is to trim and remove the surface fibres in the fabric.  Multiple cropping and shearing machines are produced with up to five cylinders, but for fine worsted and woollen fabrics three or four cylinder machines are commonly used. The process is continuous and speeds of 8 to 20 yards per minute are obtained.12 6
  7. 7. 17-Jan-12 Shearing Machine Schematic13Singeing Definition Singeing is defined as the process carried out for the purpose of removing the loose hairy fibres protruding from the surface of the cloth, thereby giving it a smooth, even and clean looking face.  Fabric may be passed over A.Heated plates or rolls B.Heated wires 2.Fabric moves directly into quench box  Problems  Flame Gaps-singe streaks14 Melt balls-may dye darker 7
  8. 8. 17-Jan-12Singeing Singeing Methods: According to the singeing machineries which are used for singeing. Singeing methods are classified into three types. The methods are: Plate singeing Roller singeing Gas singeing15 Gas Singeing  In this methods, gas burners are used to singe one or both sides of the fabric during a single passage over the flames.  The machine consists of two or more burners .  The width of the sets of burners can be adjusted to suit the width of the fabric.  The length of the flame and hence the intensity of heat can also be adjusted.  After the singeing process the fabric is passed through the quenching box. Precautionary steps:  The dry cloth should be singed to avoid scorching of fabrics  While singeing the burner should be ignited after the run of cloth.  While stopping the machine the flames should be first extinguished and then the machine should be stopped.  Singeing room should be separated from other departments in the mill.16 8
  9. 9. 17-Jan-12 Advantages: •Even singeing is the very good advantage of Gas singeing method. •Fibre ends present at the interstices are also singed. •Tubular knit fabrics can be singed by using gas singeing. •The speed of transmission of the cloth through the singeing machine can adjust to suit the amount of singeing required.17 Before& After Singeing18 9
  10. 10. 17-Jan-12 Mechanism of Gas Singeing19 A - Cloth H J B - Hot cylinder C - Guide rollers D - Gas burners E - Water sprayer D F - Squeezing rollers G - Steam chamber H - Hood J - Exhaust fan C C G D D FA C C F C C E D B Figure 3 – Gas Singeing Machine20 10
  11. 11. 17-Jan-12Singeing units for Knit-goods  The singeing temperatures for the knit goods should be appropriate for the fibre composition of the knits on the hosiery material.  It is well known that the knit fabrics are markedly sensitive to tension.  It is, therefore necessary in the special singeing units suitable for such fabrics, that care should be taken during the fabric entry, fabric run and fabric delivery of the tension sensitive material.21 Circular Singeing Machine: Tubular Knit22 11
  12. 12. 17-Jan-12 Circular Singeing Machine: Tubular Knit23 Testing of Singeing  By Visual method  Analysis of Pilling method.24 12