Sunday, October 14, 2018
General terms to be used in textile
Textile is a very broad subject(today a field of the industry). It is directly linked with human civilization. It is much more difficult to define the textile in a few words or lines exactly. Some definitions are being given below:
“As a layman, we can say that textile is a material, which is used for covering, binding, tying and packaging purpose”
“Textile is a material which consists of textile fibres such as natural,re-generated or man-made fibres and manufactures through some mechanical, chemical and or manual processes”
USES OF TEXTILES:
“When textiles were invented, its use was to cover the body and to protect the human body from the atmosphere only”. As human civilization developed, human needs increased along with human development. People learned about various uses of textiles in their life.
Some common uses of textiles are given below:
· Carry bags
· Car seating, tire cord(automobile industry)
· Medical textiles
· Aeronautical industry( air balloons, parachutes,)
· Air filter, water filter, oil filter
· Home furnishing( sheets, curtains, table linen, kitchen linen etc.)
· Industrial cloths ( felt)
· Electrical industry( for insulation)
· Bulletproof jackets
· Agro textiles
· footwear industry.
Except for these uses, there may be many more uses of textile products in human life.
“An element made of any material having hundred or more times longer in comparison to its diameter called fibre”.
TEXTILE FIBRE : DEFINITION:
“A fibre having the length to diameter ratio of more than 100 and some basic characteristics is called textile fibre”. These basic characteristics of a textile fibre are given below:
· Required strength.
· Elongation and elasticity
· Cohesive force to bind the fibres to each other.
PROPERTIES OF TEXTILE FIBRES:
End use of textile fibre is decided by taking into consideration of its properties. There are some characteristics that are essential and most important for any textile fibre. “The essential properties of a fibre to make it textile fibre are known as primary properties and those properties which may increase its utility, desirability, and value are called the secondary properties of a textile fibre”
PRIMARY PROPERTIES OF A TEXTILE FIBRE:
Some primary properties of a textile fibre are given below:
· Evenness of a fibre
· Fibre strength
· Fineness of a fibre or micronaire value
· Specific gravity or density
· Tenacity of a fibre
· Elongation or elasticity
“a continuous strand of twisted textile fibres is called yarn”. The yarn is used in weaving and knitting.
“a continuous strand of two or more plies of yarn, in which plies of yarns are twisted together is known as thread”. It is used in needlework and the weaving of cloth.
Difference between yarn and thread:
Every thread is made of yarn. Therefore it may be referred to as yarn. But yarn cannot be referred to as a thread.
The main differences between yarn and thread are given below:
1- yarn may consist of one or more plies in it while thread always consists of more than one ply.
2-yarn is normally used in woven or knitted fabrics while the thread is mostly used in sewing and needlework like embroidery or crochet work.
3-yarn cannot be referred to as the thread but the thread can be referred to as yarn.
4-yarn is usually sold in bigger packages while the thread is usually sold in smaller packages.
5- yarn has lesser elongation than thread.
6- yarn is produced by the spinning of textile fibres while thread is produced by twisting two or more plies of yarn together.
The appearance of yarn is judged visually by the naked eyes. It also plays a decisive role in the evaluation of yarn quality. An appearance board winder is used to see the appearance of yarn. This board has black colour on one side and white colour in another side. The yarn is wrapped onto the board with the help of board winding machine in such a way that yarn coils should not be overlapped to each other. Now various type of defects is observed.
The linear density of yarn:
The linear density of yarn expresses the fineness of yarn. It is a number that indicates the length per unit weight or weight per unit length of yarn. There are two systems of expressing linear density or fineness of yarn.
· Direct system:
In this system, length remains constant and weight varies according to the fineness of yarn. Tex, denier are examples of this system.
· Indirect system:
In this system, weight remains constant and length varies according to the fineness of yarn. Ne, Nm is an example of an indirect system.
The strength of yarn:
It is the most important parameter of yarn. The strength of yarn is the force required to break the yarn. There are two methods used to observe the strength.
· Bundle strength
· Single end strength
This method is used in spun yarn only. Bundle strength does not give the correct value of yarn strength but it helps to compare two yarns of the same count. If we have to select one yarn between two same counts of yarn. Bundle strength is very useful.
In this method, the exact strength of the yarn is measured. It expresses the force required to break the single strand of yarn. It is usually measured in grams or centi of newton. The elongation percentage at breaking is also recorded in this test. The elongation of yarn plays an important role during weaving. If the yarn has no elongation, it is almost impossible to weave the fabric with this yarn. Two very important and useful parameters are obtained with the help of this test:
RKM. – the strength of yarn in terms of grams/tex.
Elongation@break – in term of percentage(%).
The yarn twist is a very important parameter. It seriously affects the performance of yarn. If the yarn has less twist than standard then fibre slippage may occur. The yarn having a low twist possesses low strength. There may be a chance of pilling formation due to low twist. It will give a soft feel and touch. If the yarn has more twist than standard. The yarn will show good strength but it will give a rough feel and touch. There may be a chance of snarling too. The amount of twist is expressed in turns/inch.
· T.P.I. – turns per inch In the yarn.
Type of twist: it shows the direction of the twist. There are two types of twist direction possible which are:
The clockwise twist of yarn is called s-twist. The slope of spirals of yarn is similar to the middle part of the English letter “S”.
The anti-clockwise twist of yarn is called a z-twist. The slope of spirals of yarn is similar to the middle part of the English letter “Z”.
Unevenness: Variation in the linear density of a continuous strand or of a portion of a strand.
The evenness of yarn is measured by the Uster evenness tester. In this test, one kilometer of yarn is passed through this apparatus. The unevenness of the yarn (U%) is observed. The following parameters are recorded in this test:
· Unevenness (%)
· Thick places per kilometer of yarn
· Thin places per kilometer of yarn
Neps per kilometer of yarn.
A spun yarn posses the following important properties:
· Fineness of yarn
· Evenness of yarn
· Degree of twist
· Twist multiplier of yarn
· Strength of yarn
· Tenacity of yarn
· Elongation at break
· Degree of hairiness of yarn
· Diameter of yarn
The fabric results after the interlacement of two series of yarn. The two different yarns are interlaced to each other at a right angle. There two types of yarn lie in the fabric. The yarn running in a longitudinal (vertical or along the length of the fabric) direction is called warp. The yarn running in a transverse (horizontal or along the width of the fabric) direction is called weft or filling. The warp and weft interlace each other in the fabric according to design. The design pattern is referred to as weave.
The main parameters of the fabric are given below:
· Warp count
· Weft count
· Ends per unit length
· Picks per unit length
· Width of the fabric
· Weight per square meter or yard
· Warp crimp
· Weft crimp
· Denting order
· Type of selvedge
· Warp pattern
· Weft pattern
· Other special effects
Warp count: the yarn running in the longitudinal or vertical direction is called warp. The yarn count used in the warp yarn is referred to as warp count.
Weft count: the transverse or horizontal yarn in the fabric is called weft or filling. The yarn count used in the weft yarn is referred to as weft count.
Ends per unit length: the vertical or longitudinal threads per unit length in the fabric are referred to as ends per unit length. It is measured in ends per inch or centimeter.
Picks per unit length: the horizontal or transverse threads per unit length in the fabric are referred as picks per unit length. It is measured in picks per inch or centimeter.
Fabric width: It is measured in inches, centimeters, or meters, etc. distance between both selvedges of the fabric is called fabric width.
Weight per square meter or yard: it is measured in grams, ounces, pounds, etc. This term is widely used to refer to the quality of the fabric. GSM or GSY terms are used to denote the weight of the fabric.
Warp crimp: it is expressed in the term of percentage. When the fabric is woven, the warp threads are shrunk because of the interlacing of the weft. If we weave one meter of fabric, more than one meter of warp length is required to weave this fabric. The difference between warp length and fabric length expressed in the tern of percentage is called warp crimp.
Weft crimp: it is expressed in the term of percentage. The difference between straightened weft length and fabric width expressed in the term of percentage is called weft crimp.
Weave: the sequence of interlacement of warp and weft is called weave.
Denting order: the sequence of passing the ends through the dents of the reed is called denting order.
Type of selvedges: in today’s weaving technology, many types of selvedges are possible. Therefore it is necessary to identify the type of selvedge in the fabric and mention it if required.
Warp pattern: when the multi-color (stipe or check fabric) warp is used to weave the fabric, the sequence of colours in the warp is determined.
Weft pattern: in the multi-colour weft fabric, the sequence of colours in the weft of the fabrics is called weft pattern.
Other special effects: many special effects are created in the fabric by using different techniques. Pleated and sheer sucker fabrics are produced by using two different series of warp. Variable pick density can be used in the fabric also. Special effects can be produced by making take-up motion inoperative.
Important properties of the fabric are given below:
· Dimensional stability.
· Tensile strength.
· Tearing strength.
· Bursting strength.
· Crease resistance.
· Air permeability.
· Abrasion resistance.
· Drape coefficient.
· Moisture absorbency.
· Water Repellency.
· Thermal conductivity
· Light permeability
· Coefficient of friction
· Sewed seam strength
· Sewed seam slippage
Fabric appearance: it is the property related to the surface of the fabric. Generally, the visual property of the fabric is termed fabric appearance. Fabric appearance is directly associated with the structure, material used, reflectance properties, and surface morphology.
Lustre of the fabric: when a person sees the surface of two different fabrics with the naked eye, he observes that there is a difference between the amounts of light reflected by both fabric surfaces. Thus we can say that “the amount of light reflected by fabric surface judged with naked eyes is termed as fabric luster”. It is also called the sheen of the fabric. It depends upon structure, type of yarn, type of material, and weaves used.
The handle of the fabric: “Fabric handle tells about the degree of softness, stiffness, hardness, smoothness or roughness of the fabric”. It is judged by touching the fabric by hand simply. Fabric handle varies according to the type of material used, fabric construction, weight per square unit of the fabric and weave, etc.
The ability of a fabric to retain its original dimensions or shape while being used for its intended purpose as expressed in the term of percentage is called the dimensional stability of the fabric. It is determined in warp direction (length) and weft direction (width) separately. It is greatly influenced by yarn count and construction used, type of material, yarn twist, weave and grams per square meter of the fabric, etc.
The tensile strength of fabric: The maximum stretching force (load) hold by the fabric without breaking, when the force (stretching load) being applied to the fabric is known as the tensile strength of the fabric. It is measured in newton per square centimeter or pounds per square inch. It depends upon the yarn strength, material type or thread count of the fabric, etc. The tensile strength of the fabric is determined separately in the warp and weft direction.
Tearing strength of fabric: The term tearing strength of the fabric is referred to as “the force required to initiate the tearing of the fabric from the split in the center of the specimen or continue tearing of the fabric”. It is also termed tearing resistance. It is measured in pounds, grams, or Newton, etc. It is determined for warp and weft direction separately. It varies according to the yarn used, thread count and type of material, etc.
Bursting strength: when the fabric is subjected to pressure, the fabric is stretched in all possible directions at the same time. When the applied pressure is increased gradually, the fabric begins to burst after a pressure limit. This pressure limit is called bursting strength. Thus we can say that “the pressure required to burst the fabric surface is termed as bursting strength of fabric”. It is measured in pounds per inch2. The type of yarn, construction of fabric, and material type influence the bursting strength of fabric greatly.
Crease resistance of fabric: “The ability of the fabric to prevent the formation of wrinkles or creases on the surface of the fabric during various uses or processes is called crease resistance of the fabric”. It greatly depends upon the type of material to be used in the fabric. The crease resistance of the fabric is expressed in the term of the crease recovery angle.
The air permeability of fabric: “The volume of air passed per second through per unit area of the fabric is called air permeability of fabric”. It is expressed in cubic centimeters per second per square centimeter. It depends upon the count of yarn, construction of fabric, and weight per square unit of the fabric.
Abrasion resistance of fabric: The degree to which a fabric is able to withstand surface wear, rubbing, chafing, and other friction forces. Abrasion resistance allows a fabric surface to resist wear. Fabrics which are abrasion resistant are useful for situations in which mechanical wearing and damage can occur.
Fabric pilling: The ball formation on the fabric surface during fabric wear due to the entanglement of protruding fibers is termed pilling. These balls on the fabric surface form due to rubbing. The pilling property of the fabric is majorly affected by yarn quality, type of material, and degree of twist of yarn to be used in the fabric.
Drape coefficient of the fabric: it is a very important characteristic of the fabric. It prescribes the fabric deformation by gravity when it is allowed to hang under its own weight. It is the ratio of the difference between the area of the draped sample and the supporting disk to the difference between the area of the specimen and the supporting disk. Its value is always less than one. The low value of the drape coefficient shows good draping properties of the fabric. It depends upon the weight per square unit of fabric, construction of the fabric, type of material, etc.
Moisture absorbency: The ability of a fabric to take in moisture. Absorbency is a very important property, which affects many other characteristics such as skin comfort, static build-up, shrinkage, stain removal, water repellency, and wrinkle recovery.
Water repellency: The water repellency of the fabric is the ability to resist the fabric to absorb moisture. It depends upon the compactness of the fabric, construction, and material used in the fabric, etc.
The thermal conductivity of the fabric: The ability of the fabric to transfer heat from a higher temperature to a lower temperature surface by conduction is termed the thermal conductivity of the fabric. The heat energy transferred per second per unit surface area of the fabric, divided by the temperature difference is called the thermal conductivity of the fabric. It is measured in watts per second per square meter. It mainly depends upon the weight per square unit, the type of material of the fabric.
Light permeability of the fabric: The ability of the fabric to allow the degree of light to pass through the fabric is called the light permeability of the fabric. It depends upon the construction of the fabric, the type of material of the fabric, etc.
The breathability of fabric: Moisture vapor transmission rate is a measure of the passage of water vapor through the fabric. It is termed as the breathability of the fabric. it contributes greater comfort for wearers of clothing for outdoor activity. It is measured in grams/metre²/day. It depends upon the fabric construction, weight per square unit, and type of material used in the fabric.
Washability of fabric: The ability of fabric to wash manually or mechanically with water and soap without the change in colour, dimensional stability, and appearance of the fabric is called the washability of fabric. It depends upon the yarn quality, the type of material used, and the quality of dyeing, etc.
The coefficient of friction: It tells about the frictional characteristic of the fabric surface. When a block covered with fabric is kept over an inclined surface covered with the same fabric surface, at a certain degree of angle the block starts to slide due to its own weight. The tangent of this angle is called the coefficient of friction of fabric. The coefficient of friction varies according to the type of yarn, type of material, weave of the fabric, and finish used in the fabric.
Sewed seam strength: when the two fabrics join together it needs similar strength at the point of joint as the original fabric. The seam strength of fabric ensures the durability of a garment and other products. Seam strength depends upon the construction of the fabric, weave, type of material, etc.
Sewed seam slippage: it is a very important property of the fabric. It ensures to prevent of slippage of seams during wear, abrasion, and stress in the garment. When the stitching needle penetrates the fabric, it does not rupture the yarn of the fabric due to the mobility of yarn in the fabric. If the yarn has a lack of yarn mobility in the fabric, the stitching needle does rupture the yarn which causes sewed seam slippage in the garments. It is greatly influenced by fiber content, yarn construction, tightness, and thread count. The fabric construction (EPI, PPI, count, weave type) plays a major role in the performance of the seam. The cover factor increases with the increase in EPI and PPI, thus resulting in greater fabric strength, the greater the resistance to fabric and seam breakage.
Flammability: This is a very important characteristic of the fabric. Flammability of the fabric is the characteristic of the fabric that pertains to its relative ease of ignition and relative ability to sustain combustion. It depends upon the type of material used in the fabric.
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