Saturday, May 13, 2017

Textile Sizing: Important Process of Weaving Preparation

Textile Sizing:
Textile Sizing is one of the most important operations in weaving preparation. After winding and warping process yarn is sized during beam preparation. Sizing is the process of applying a protective adhesive coating on the surface of the yarn, so that the warp yarn can withstand against the weaving forces. Another way, sizing is an application of size and lubricants to the warp yarns. Sizing is called

Sizing is used to protect the warp from the rigours of weaving. The size is a film-forming polymer such as starch and is applied from a solution. Sizing gives a protective coating on yarn surface to tolerate the friction on loom machine. As a result yarn breakage and yarn rupture will reduce during weaving process. So sizing is called heart of weaving.

Objectives of sizing:
To improve weave ability of warp yarn by making it smoother, stronger, and more resistant to abrasion against various machine parts.

An optimal size recipe, which guarantees a process safe work-ability and a good weaving behavior.

Sizing ingredients and its function:


Ingredients
Name
Function
Adhesive
Starch, PVA, CMC, CMS, PES
To make warp yarn more strong, elastic.
Lubricating agent
Tallow, Japan wax, Linseed oil, Coconut oil, Palm oil
To increase smoothness, slippery/flexibility and reduce friction.
Antiseptic
Salicylic acid, Zinc chloride, Phenol
To save the yarn from various micro organism like mildew.
Deliquescent
Glycerin, Ca & Mg chloride
To absorb moisture from air for preventing excessive drying of yarn.
Tinting agent
Blue
To reduce yellowness and to increase brightness.
Anti foaming agent
Benzene, pyridine
To remove foam from sizing mixture.
Wetting agents
China clay, Sodium phosphate
To increase size exhaust with uniform distribution.
Typical sizing recipe:

Water = 85%
Total sizing ingredients = 15%

Sizing ingredients

For Light Sizing
For Medium Sizing
For Heavy Sizing
Flour – 100 lbs
Wax – 5 lbs
Tallow – 4 lbs
Flour – 100 lbs
Clay – 34 lbs
Tallow – 15 lbs
MgCl2 – 1 gallon
ZnCl2 – ½ gallon
Flour – 100 lbs
Clay – 134 lbs
Tallow – 14 lbs
MgCl2 – 5 gallon
ZnCl2 – 2 gallon
Modern sizing process:
Textile Sizing is a very important process to get a good strength, flexible and smooth yarn, which is suitable for modern loom and in particular nowadays, as faster and faster machine is used and quality is required at the highest level.

A saying from the old said “a well prepared and sized warp is already half fabric”. A good sizing machine is equipped with every device able to ensure good control levels on tension, elongation, temperature, squeezing etc but they must also be able to choose the necessary parameters according to the items to be processed, their physical-chemical composition and also to choose those that are most suitable for that processing and for the following operations of desizing and dressing.

Modern sizing process
Fig: Modern sizing process
The warps were then moved to chambers with some return cylinders where they were dried with hot air (the most modern machines were equipped with copper drying cylinders heated by steam), then they were crabbed on beams going to the loom.

Effect of sizing on yarn properties:

Name of the properties
Property change after sizing
Yarn strength
Increase yarn strength
Elongation
Reduce elongation
Flexibility
Reduce flexibility
Frictional properties
Reduce frictional properties
Smoothness
Increase smoothness
Absorbency
Reduce absorbency
Weight of yarn
Increase weight of yarn
Hairiness
Reduce hairiness
Image courtesy: http://nptel.ac.in