SIZING BEFORE DENIM WEAVING

SIZING

Although the quality and characteristics of the warp yarns coming out of the winding, warping and dyeing processes are quite good, they are still not good enough for the weaving process for most of the yarns. The weaving process requires the warp yarns to be strong, smooth and elastic or extensible to certain degree. To achieve these properties on the warp yarns, a protective coating of polymeric film forming agent (size) is applied to the warp yarns prior to weaving; this process is called slashing or sizing. The main purposes of slashing are as follows:

1. To increase the strength of the yarns
2. To reduce the yarn hairiness that would cause problems in weaving process
3. To increase the abrasion resistance of the yarn against other yarns and various machine elements
4. To reduce fluff and fly during the weaving process for high speed weaving machines.

One sizing tank is provided after the drying zone. The capacity of the size box is about 400 liters. Sizing material is provided automatically by dosing system or it can be manually added.

DRYING ZONE

After the size box the yarns go through the dryer section. The wet yarns are dried by using cylinder drying. Cylinder drying is done using steam heated hot rolls called the drying cylinders. The cylinders are coated with Teflon to prevent sticking of the yarns on the cylinders. The drying zone contains 14 cylinders.

ACCUMULATOR:

Accumulator is also known as compensators. After drying two accumulators are provided on the machine. Whose function is to minimize chance of stoppage of machine because of the change of beam on the head stock and insertion of rods in the leasing zone they accumulate the extra warp when the speed is reduced from the headstock by moving assembly to upward direction. When the head stock is moved with a greater speed the excess warp is removes from the accumulator.

LEASING ZONE

Due to the nature of sizing, the yarns in the sheet may be stuck together at the exit of dryer section. Therefore they are separated into individual ends using leasing rods. The individual sheets of yarns from each section beam are separated.

EXPANSION COMB

Pins in the expansion comb separate the yarns within each sheet. With the expansion comb the warps are spread according to the required width of the weaver’s beam.

BEAMING

The yarns are wound on to weaver’s beam at the headstock. Maximum beam width of 4000 mm can be used, usually 3600 mm is used. A pressing roller is pressing the warp yarn for uniform tension winding. A guide roller guides the yarns to the weaver’s beam. A pressing roller is pressing the warp yarn for uniform tension winding. A machine speed of 100-110 m/min. is used.

TRANSPORTATION OF BEAMS:

After the winding of dyed warp beams the from the head stock the samples of the yarn are taken to laboratory for testing and then it is transported to the weaving department.