Warping and its Types

Warping:

Warping is a process in which number of the yarns end from the yarn packages or cones are wound on the warping beams.

Or

Warping is transferring many yarns from a creel of the single end package forming a parallel sheet of the yarn wound on to a beam.

Objectives of the warping:

         

The object of warp preparation is to transfer yarn from the spinner's package to a weaver's beam that can be placed behind a loom ready for weaving. A weaver's beam usually contains several thousand ends and for a variety of reasons, it can seldom be made in one operation.

There are two main objective of the warping

Ø Collection of the number of the yarns end required in the fabrics

Ø Winding a specific type of the package as required by subsequent process i.e. warper’s beam or ball etc

Types of the warping:

There are three common types of the warping

Ø High speed warping (Direct warping)

Ø Section warping (Indirect warping)

Ø Ball warping

High Speed Warping:

          In this system single end of the yarn from the cones or packages are directly wounded on the warping beams. This is the winding of total number of warp ends in full width in a single operation from creeled bobbin.

This process or system is used for the mass production. This is used to make smaller intermediate beams called warper’s beams. These smaller beams are combined later at the sizing stage to produce the weaver’s beam. This process is called beaming. Therefore, for if the weaver’s beam contains 10,000 warp ends, then there would be-say – 10 warper’s beams of 1,000 ends each. If this weaver’s were to be made in one stage, the creel would have to have 10,000 yarn packages, which is impossible to manage.

Section of High Speed Warping:

Ø Creel

Ø Warp Break Sensor

Ø Expanding comb

Ø Pressure roller

Ø Beam

Section Warping:

          In the section warping, first the yarn ends from the creel are wounded on the warping section beams which are winding section. After this, this section yarn are then wounded on the warping beams. Then the warping beams without sizing are applied to the loom to produce the grey fabrics. This system takes time so the production will not so good. It is clear from the above it is two step processes.

Feature of Sectional Warping:

Ø This is suitable for making checked, stripped or other fancy fabric.

Ø Fabrics which don’t required sizing

Ø Fabric with strip of different colors or different type of yarns

Ø Less no of ends of warp in the sheet

Ø The production is less in sectional warping

Ø It is less efficient than high speed warping

Where length of the warp are comparatively small as this is slow speed process and can’t coup up with mass production orders.

Ball Warping:

                   In this system the large no the strands of the yarn of specific length in the form of loose untwist rope are wounded.

This system is mainly used when the yarn is dyed for denim fabrics. This rope consists of the 50 to 100 yarns. Such a beam is termed as ball. After the dying process the rope ends are again separated and wound on another warping beams (long chain beaming). Warp beam so produced are then combined on the sizing machine for applying the size and then wound on a weaver’s beams.

Machine of warping:

         

There are two main parts of the machine of the warping:

Ø Creel   

Ø Head Stock

Creel:

      The creel is a structure which is used to hold the cones on the spindle.

Creel structure:

Spindle:

          Spindle is a part of a machine around which cone turns at the time of withdrawal of yarn or place for supply package.

Pegs:

        This is used to hold the cones on the creel

Guides:

          Guides are a component for controlling the path of a running material.

Tensioners:

     This is device which is use the keep the strength in warp yarn constant.

Stop motion pins.

Creel capacity:

    Creel capacity depend upon the

Ø No the rod of the creel

Ø No the spindles that holds the cones on the creel

Types of the creel:

       There are two type of creel according to the shape:

Ø V-Shape Creels

Ø H-Shape Creels

Ø Mobile Creels

Ø Magazine Creel

Ø Swivel Frame Creel

Differences between Sectional and High Speed Warping

High Speed Warping	Sectional Warping
1. Beam warping is used for long runs of grey fabrics & simple pattern.	1. Sectional warping is used for short runs especially for fancy pattern fabrics.
2. The amount of colored yarn is less than 15% of the total.	2. Greater amount of colored yarn is used.
3. High production.	3. Low production.
4. Large amount of yarn required.	4. Small amount of yarn required.
5. Single yarn is used.	5. Twisted yarn is used.
6. Less expensive.	6. More expensive.
7. It is most widely used for cotton, linen, woolen & worsted yarn.	7. It is most widely used for cotton, silk & synthetic yarn.
8. Uniform tension of yarn.	8. Less uniform tension of yarn.
9. Weavers beam is produced after sizing.	9. Weavers beam is produced after warping.
10. Creel capacity is more.	10. Creel capacity is less.
11. Beam warping is more widely used.	11. Sectional warping is not widely used.

DYEING AND PRINTING OVERVIEW

DYEING AND PRINTING

Dyeing          Coloration of textile Material in a single solid color

Printing        Coloration of textile material with multi colors to have some specified design with repeat

DIFFERENCE BETWEEN DYEING AND PRINTING

DYEING•

UNIFORM COLOURATION ALONG LENGTH AND WIDTH OF FABRIC• USUALLY SINGLE COLOUR IS POSSIBLE. •NO DIFFERENCE IN COLOUR BETWEEN FRONT AND BACK SIDE OF FABRIC• AQUEOUS DYEING MEDIUM OF LOW VISCOSITY •DYEING IN BATCHWISE, CONTINUOUS OR SEMI-CONTINUOUS METHOD.• FABRIC DYEING IN OPEN WIDTH OR ROPE FORM.• DYEING IN FIBRE,YARN,FABRIC,GARMENTS

            Dye-stuff ( they are the colouring materials )

• Water
• Auxiliaries ( they are the helping materials that increase the dyeing properties )

STAGES OF THE DYEING PROCESS

                       Preparation of Fabric

Preparation of the dyeing sol.

Actual dyeing ( padding , drying & fixation )

Soaping & washing

Drying

STEPS

1. Migration
2. Adsorption
3. Absorption
4. Diffusion
5. Fixation

DYE STUFF CLASSIFICATION

Dyes can be classified on four parameters but basic are two:

1. Base on Solubility
2. Base on Application or Uses
3. Base on Chemical Constituent
• Base on ionic structure

Application process

The dyeing of a textile fibre is carried out in a solution, generally aqueous, known as the dye liquor or dyebath. For true dyeing (as opposed to mere staining) to have taken place, the coloration must be relatively permanent; that is, not readily removed by rinsing in water or by normal washing procedures. Moreover, the dyeing must not fade rapidly on exposure to light. The process of attachment of the dye molecule to the fibre is one of absorption; that is, the dye molecules concentrate on the fibre surface.

TYPES OF FORCES ACTING

There are four kinds of forces by which dye molecules are bound to fibre:

1. ionic forces,
2. hydrogen bonding,
3. van der Waals' forces, and
4. covalent chemical linkages.

DYEING METHODS

• Exhaust Dyeing
• Semi-continuous method
• Continuous metod

DYEING MACHINES FOR BATCH METHOD

Fiber dyeing

• Loose stock dyeing m/c

Yarn dyeing

• Spindle package dyeing m/c
• Hank dyeing m/c

Fabric dyeing

• Beam dyeing m/c
• Jigger dyeing m/c
• Winch dyeing m/c
• Jet dyeing m/c
• Soft dyeing m/c

Garment dyeing

• Peg dyeing m/c
• Rotary drum dyeing m/c

DYEING MACHINES FOR SEMI-CONTINUOUS METHOD

• Fabric dyeing
• Pad –batch pad thermo sol

DYEING MACHINE FOR CONTINUOUS METHOD

Fiber dyeing

• Continuous fiber dyeing m/c

Yarn dyeing m/c

• Slasher dyeing m/c
• Rope dyeing m/c

Fabric dyeing m/c

• Pad-thermo sol dyeing m/c

TEXTILE PRINTING

Printing is different from dyeing in that way as it is designed to produce multicolored pattern on textile material by using printing paste rather than

METHODS OF PRINTING

The four main methods of textile printing are

1. block,
2. roller,
3. screen, and
4. heat transfer printing.

In each of these methods, the application of the colour, usually as a thickened paste, is followed by fixation, usually by steaming or heating, and then removal of excess colour by washing. Printing styles are classified as direct, discharge, or resist. In direct printing, coloured pastes are printed directly on the cloth. For discharge printing, the cloth is first dyed with a background colour, which is destroyed by reagents, or reducing agents, carried in a print paste. This action may leave the discharged design white on a coloured background, although print pastes may also contain colouring matters not destroyed by the discharging agent, producing a coloured design. In the resist process, the cloth is first printed with a substance called a resist, protecting these printed areas from accepting colour. When the cloth is dyed or pigment padded only those parts not printed with the resist are dyed. A special application of this technique, imparting plissé effects, is the printing of the fabric with a resist, followed by treatment with caustic soda.

PRINTING PASTE

The printing paste is an emulsion of dye, thickener and hydrocarbon solvent and surface active agents. The uniform consistency of the printing paste is referred to as its viscosity ( the ease with which the paste flows ). The viscosity of the printing paste is very important as it influences the clarity & appearance of the printing pattern.

STAGES IN PRINTING PROCESS

1. Preparation of the design
2. Preparation of the printing paste
3. Actual printing ( making an impression of the paste on the fabric )
4. Drying of the printing paste
5. Fixation as after treatments
6. Soaping & washing
7. Drying

GENERAL THEORY OF PRINTING

The interaction on steaming b/w the dye , fibre, water, thickener, and hydrocarbon solvent. More specifically, it explains how with in the printing paste:

• Force of repulsion is developed b/w the dye molecules and constituents of the printing paste; and
• Force of attraction is developed b/w the dye molecules and the textile material.

THEORY OF PRINTING

• The printing paste which is applied to the textile material consists of dye, water thickeners & hydrocarbons solvent. After the printing paste is applied, the textile material is usually steamed.
• Steam enable the dye molecules to migrate from the surface of the fibres and enter the fibres polymer system. Steaming swells the fibres and ensures the better penetration of the dye and improve color fastness properties of the textile material.

METHODS & MACHINES FOR PRINTING

1) Block Printing

Wooden blocks, carved with a design standing out in relief, are made from solid pieces of wood or by bonding closely grained woods with cheaper ones. When designs include large areas, these are recessed and the space

2) Roller Printing

DIFFERENT STYLES OF PRINTING

Direct style: In direct style, dyes are printed directly on the required place of the fabric with the multicolored design.

Discharge style: Fabric is first dyed and then printed with a paste containing a discharging agent thus white or colored effect can be produced on colored ground.

Resist style: First a resisting agent is printed on white fabric and then fabric is dyed.

Special style:1) Transfer printing style,2) Burnout printing style

TEXTILE FINISHING PROCESS

Types of Processes and Objectives:

The term finishing includes all the mechanical and chemical processes employed commercially to improve the acceptability of the product, except those procedures directly concerned with colouring. The objective of the various finishing processes is to make fabric from the loom or knitting frame more acceptable to the consumer. Finishing processes include preparatory treatments used before additional treatment, such as bleaching prior to dyeing; treatments, such as glazing, to enhance appearance; sizing, affecting touch; and treatments adding properties to enhance performance, such as preshrinking. Newly formed cloth is generally dirty, harsh, and unattractive, requiring considerable skill for conversion into a desirable product. Before treatment, the unfinished fabrics are referred to as gray goods, or sometimes, in the case of silks, as greige goods.

Finishing is process in which fabric is treated with some mechanical or chemical process before or after dyeing or printing to give the fabric a fancy / novelty touch to make it more durable, flexible soft and good in appearance and handle.

Chemical finishes

1. Crease resistance/ wrinkle free / resin finish
2. Soft finish
3. Water professing
4. Water repellent/ oil repellent/ soil repellent
5. Weighting finish
6. Anti-bacterial finish
7. Flame proofing
8. Stiffening finish
9. Anti static finish
10. Sanforizing finish

MECHANICLE FINISHES

1. Heat setting finish ( stentor – pin type or clip type )
2. Raising finish ( teasel raising m/c & card wire m/c )
3. Peaching / sueding/ emerizing finish ( emerizing m/c )
4. Sanforizing finish ( rigmal m/c & confined passage )
5. Calendaring finish
• Universal calendar
• Friction calendar
• Embossing calendar
• Schriener calendar

UNDESIRED PROPERTIES

1.      Pilling

2.      Creases ( bad effect but sometimes required as creep )

3.      Stiffness

4.      Water repellency

5.      Shrinkage

6.      Shade variation

7.      Wrinkle

8.      Unclear vision

9.      Weight loss

VALUE ADDED EFFECTS

1. Lustre
2. Soft handle
3. Fire proofing
4. Water proofing
5. Fragrance
6. Crease resistance
7. Dimension stability
8. Weighting
9. Embossing
10. Anti-bacterial

Optical fiber and its Applications

                                                                                Fiber Optics

An optical fiber is a flexible, transparent fiber made of glass (silica) or plastic, slightly thicker than a human hair. It functions as a waveguide, or “light pipe”, to transmit light between the two ends of the fiber. The field of applied science and engineering concerned with the design and application of optical fibers is known as fiber optics.

Principle

The principles on which optical fibers work are

·         Index Of Refraction

·         Total Internal Reflection

Index of Refraction

The index of refraction is a way of measuring the speed of light in a material. Light travels fastest in a vacuum, such as outer space. The speed of light in a vacuum is about 300,000 kilometers (186,000 miles) per second. Index of refraction is calculated by dividing the speed of light in a vacuum by the speed of light in some other medium. The index of refraction of a vacuum is therefore 1, by definition. The typical value for the cladding of an optical fiber is 1.52. The core value is typically 1.62. The larger the index of refraction, the slower light travels in that medium. From this information, a good rule of thumb is that signal using optical fiber for communication will travel at around 200,000 kilometers per second. Or to put it another way, to travel 1000 kilometers in fiber, the signal will take 5 milliseconds to propagate.

Total Internal Reflection

When light traveling in an optically dense medium hits a boundary at a steep angle (larger than the critical angle for the boundary), the light will be completely reflected. This is called total internal reflection. This effect is used in optical fibers to confine light in the core. Light travels through the fiber core, bouncing back and forth off the boundary between the core and cladding. Because the light must strike the boundary with an angle greater than the critical angle, only light that enters the fiber within a certain range of angles can travel down the fiber without leaking out. This range of angles is called the acceptance cone of the fiber. The size of this acceptance cone is a function of the refractive index difference between the fiber's core and cladding.
In simpler terms, there is a maximum angle from the fiber axis at which light may enter the fiber so that it will propagate, or travel, in the core of the fiber. The sine of this maximum angle is the numerical aperture (NA) of the fiber. Fiber with a larger NA requires less precision to splice and work with than fiber with a smaller NA. Single-mode fiber has a small NA.

                                                                               

Construction

Modern optical fibers are formed by two layers of glass. As shown in fig, the fiber core (8 μ m) is surrounded by a concentric core of lower index glass known as cladding (125 μ m).

The cladding is surrounded by a protective layer. The total internal reflection occurs as the core-cladding interface. In fibers designed for high-speed telecommunication, the core is only a few microns in diameter, not much larger than the wavelength of the light used. In such cases, the full electromagnetic wave picture must be describing the propagation of the light. However, when the highest data transmission rate are not required, fibers with a "large" core of perhaps a hundred micron or more used such fibers are known as multimode fibers. For multimode fibers, ray, picture is adequate to describe the behavior of the light.

                                                                              

Types of Optical Fiber

There are following types of Optical Fibers

Multimode Fiber

Multimode fiber, the first to be manufactured and commercialized, simply refers to the fact that numerous modes or light rays are carried simultaneously through the waveguide. Modes result from the fact that light will only propagate in the fiber core at discrete angles within the cone of acceptance. This fiber type has a much larger core diameter, compared to single-mode fiber, allowing for the larger number of modes, and multimode fiber is easier to couple than single-mode optical fiber. Multimode fiber may be categorized as step-index or graded-index fiber.

Single-mode Fiber

Single-mode fiber allows for a higher capacity to transmit information because it can retain the fidelity of each light pulse over longer distances, and it exhibits no dispersion caused by multiple modes. Single-mode fiber also enjoys lower fiber attenuation than multimode fiber. Thus, more information can be transmitted per unit of time. Like multimode fiber, early single-mode fiber was generally characterized as step-index fiber meaning the refractive index of the fiber core is a step above that of the cladding rather than graduated as it is in graded-index fiber. Modern single-mode fibers have evolved into more complex designs such as matched clad, depressed clad and other exotic structures.

Photonic fibres

In photonic fibres the transmission of light is guided by a number of cavities around the core. The core may be made in glass or even an air cavity! These are new fibres on the market and for the moment (2008) their performances are still under the requirements for astronomical applications.

Applications of Optical Fibers

·         Telecommunications specialty fiber applications in building EDFAs, dispersion compensation, and amplification—long haul applications in standard transmission and connectivity are served by our sister division

·         Medical grade fibers, cable and assemblies used in sensing, surgical procedures, and communications between devices and control and analysis equipment within sensitive environments such as MRI and radiation suites

·         General Industry factory environments and secure installations

·         Commercial Laser encompassing fiber laser and amplifier components for micro
and macro applications 

·         Government, Aerospace and Defense also encompasses navigation systems, payout applications and in-flight entertainment

·         Mass Transit and Transportation Hubs terminal-based and en route transportation applications, navigation, and RoHS, REACH, and Low Smoke Zero Halogen compliance

·         Windpower connections within and between towers and the central operations center

·         Solar specific fiber optic needs in solar voltaic farms

·         Oil & Gas down-hole well applications, Distributed Temperature Sensing (DTS)

·         Fiber Sensing all forms of detection with optical fiber, Fiber Bragg Grating-based solutions

SHEARING:

“Shearing” is a cutting process to remove protruding fibers on the surface of fabric.

SHEARING PROCESS STAGES

1.     Brushing of cloth.

2.     Cutting of projecting fibers.

3.     Suction of fiber removed by shearing.

SHEARING MACHINE PARTS & WORKING

1.     Outer casing which cover the machine assembly.

2.     A guide roller which just facilitates the movement of fabric.

3.     Two brushing rollers, first is in opposite to the direction is which the fabric move and second is in the same direction of the fabric. They are use to remove any type of hanging extra materials which can disturbance in process of shearing.

4.     Shearing Machine Parts & their function

5.     An adjustable bed- plate provides a base support for shearing action between the bed plate and cutting plate.

6.     A cutting roller with bladed mounted on it in spiral form which provide extra length of cutting blades from one end to the other  and make sure the contact between the blades and fabric in whole one revolution. Which increase the shearing rate projecting fibers as in a straight blade plate length is less then the spiral blade. Setting of blade require be accurate for a clear cut finish.

7.     A fan after cutting blades used for the removal of the removed projecting fibers.

MACHINE USED FOR SHEARING

            Shearing machine is used for shearing.

AMOUNT OF SHEARING DEPENDS

1.     The amount of projecting fibers.

2.     Length of the projecting fibers.

3.     Speed of bladed roller. (40 meters/min)

4.     Setting between Blade roller to Bed.

5.     Sharpness of the bladed roller

De-sizing Process and its types

De-sizing Process

A process carried out to remove the sizing material (like starch) from the cloth. 

Objective of De-sizing

             1.     To eliminate the water repellent nature of sized cloth.             
             2.     To increase the absorbency.             
             3.     To reduce the consumption of chemicals in subsequent process.

Importance of De-sizing

                The importance of de-sizing is mainly because of water repellent nature of “Sizing materials”. So, it is important to remove the size material before conducting any  coloration or finishing process.

Enzymatic desizing

What are enzymes?

Name

·         Greek, meaning “In Yeast”

Nature

·         Bio-catalyst (proteins)

Structure

·         Usually large & complicated

Properties

·         Specific action

·         Thermo ability

·         Low energy of activation

·         Narrow working pH arrange

Classification

·         According to origin

·         According to action

·         According to structure

·         According to working temperature

Sources of Amylases

·         Malt

·         Bacteria

·         Pancreas

Requirements of desizing:

• Desizing materials
• Desizing methods
• Desizing machine

Desizing processes

Desizing, irrespective of what the desizing agent is, involves impregnation of the fabric with the desizing agent, allowing the desizing agent to degrade or solubilise the size material, and finally to wash out the degradation products. The major desizing processes are:

• Enzymatic desizing of starches on cotton fabrics
• Oxidative desizing
• Acid desizing
• Removal of water-soluble size

Enzymatic desizing

Enzymatic desizing is the most widely used desizing process of degrading starch size on cotton fabrics using enzymes. Enzymes are complex organic, soluble bio-catalysts, formed by living organisms that catalyze chemical reaction in biological processes. Enzymes are quite specific in their action on a particular substance. A small quantity of enzyme is able to decompose a large quantity of the substance it acts upon..

Amylases is the enzyme that hydrolyses and reduce the molecular weight of amylose and amylopectin molecules in starch, making it water soluble enough to be washed off the fabric.

Effect of PH and Temperature on enzyme desizing

Effective enzymatic desizing require strict control of pH, temperature, water hardness and electrolyte addition Activity of enzymes increase with temperature; however, above a critical temperature, enzymes are deactivated. The effectiveness of enzymes exhibit a maximum at certain temperatures, usually 40 -75 0C. Bacterial enzymes are the most thermally stable and can be used up to 100 0C under special stabilizing conditions. Certain salts increase the activity of specific enzymes. Pancreatic amylase is ineffective without the addition of salt. A combination of sodium chloride

Exhaust Process

                           Enzyme                    4 g/l

                            NaCl                        4 g/l

                           Wetting Agent         1 g/l

            Continuous Process

1. Saturate fabric with a solution containing:

Bacterial Amylase 0.8 - 1.0 %

Wetting agent 0.1 - 0.2 %

Sodium Chloride 10 %

2. Hold:

Open-width Range: Steam 1 to 2 minutes at 200 to 212 ⁰F.

Rope Range: Store in J Box for 20 to 30 minutes at 170 to 180 ⁰F. or

over night at room temperature.

3. Thoroughly rinse with hot water, 175 0F or hotter.

           

Oxidative desizing

In oxidative desizing, the risk of damage to the cellulose fiber is very high, and its use for desizing is very rare. Oxidative desizing uses potassium or sodium persulfate or sodium bromite as an oxidizing agent.

Acid desizing

Cold solutions of dilute sulphuric or hydrochloric acids are used to hydrolyze the starch, however, this has the disadvantage of damaging  cellulose fiber in cotton fabrics.

Removal of water-soluble sizes

Fabrics containing water soluble sizes can be desized by washing using hot water, perhaps containing wetting agents (surfactants) and a mild alkali. The water replaces the size on the outer surface of the fiber, and absorbs within the fiber to remove any fabric residue.

Assessment of size removal:

A drop of iodine solution placed on a test specimen resulting in a characteristic blue color is the universal test for identifying starch. It can be used as a qualitatively test to show whether all the starch was removed. Absence of the blue color signifiesthat all the starch has been removed. The intensity of the color is some what related to how much is left. Usually, if the color is faintly perceptible, the remaining starch will come out in the scouring and bleaching steps that follow.