Fabrics with a pile surface in woven fabrics can be obtained in various ways. They can be divided into cut loops, uncut loops (towel) or weft pile, warp pile.
When the warp threads are pulled from pile surface fabrics such as cord or corduroy fabrics, it is seen that they are covered with pile threads of regular length. The pile of weft pile fabrics such as cord and corduroy is always cut. In plain velvet, weft threads are covered with short pile threads. The pile is perpendicular to the yarn to which it is attached. Therefore, if the pile is attached to the warp thread, the pile thread must be the weft. Or it could be vice versa. Used in dress, suit, home furnishing etc.
Plain velvet fabric is obtained in 3 stages. Two layers of fabric are woven simultaneously on a double-action shuttle loom. As the fabric leaves the loom, the vertical weft threads separate to form two separate fabrics, each having vertical pile surfaces. The longitudinal warp threads form piles in the weaving process of velvet, and finally, by passing the pile fabric through scissors, the pile is transformed into a flat, smooth surface.
Velvet fabrics are named according to the difference in pile height. The ones with short pile (2 mm) are called “Velvet” and the ones with longer pile (more than 2 mm) are called “Plush”. Velvets are divided into 2 groups according to the weaving technique as warp velvets and weft velvets. While the loops (pile layer) in warp velvets are formed by warp yarn with 2 warp 1 weft system; In weft velvets, the loops (pile layer) are formed by the weft yarn with 1 warp and 2 weft systems.
Velvet fabrics consist of two groups of yarn systems:
1) Threads that make up the ground fabric,
2) The yarns that make up the pile surface.
Velvet fabrics are defined as fabrics with warp on the ground fabric. In other words, velvet is a soft and voluminous fabric that covers the surface of the fibers left in a certain length, giving it a pile (hairy) appearance. Originally, velvet was produced as a short, dense warp pile fabric woven from silk warp. Today, short, dense warp pile fabrics and weft pile fabric velvet, which are made partly from silk or rayon and partly from other fibers or entirely from other yarns (wool, cotton, etc.), are also called velvet.
Velvet fabrics are named according to the difference in pile height. “Velvet” for short pile (2 mm) fabrics, and “Velvet” for fabrics with longer (more than 2 mm) pile "plush" called
The distinctive feature of velvet from other fabrics is the loop or yarn bundle structure that protrudes outward on the surface. Thus, in addition to its smooth rich surface appearance, it has a surface consisting of cut short fiber bundles that are very close to each other, giving a pleasant soft feeling to the hand. This feature is completely achieved in the weaving machine. It is possible to create a soft structure by creating fiber protrusions on the surface of the fabric with physical finishing processes. Although there is misuse in the market, the tissues obtained by this method are also called velvet. It would be more correct to call them "pile fabric".
Velvet fabric structures; it is examined by the connection patterns of the yarn groups that make up the velvet fabric;
a) Definition of pile and pile surface,
b) Pile warping,
c) Pile scarf,
d) Ground warp,
e) Ground weft
f) Connection types of pile yarns in velvet fabrics.
Pile and Pile Surface:
The yarn ends, which are formed by yarn bundles and extend outward from the surface of the fabric, whose purpose is to create a certain effect on the surface of the fabric, are called pile. If the surface of the fabric is covered with these piles, the fabrics are generally called pile surface fabrics. They are fabrics with pile surface in velvets.
Pile Warping:
It is the name given to the warp threads that form piles in warp velvets. In the flat velvet loom, the pile warp is wrapped in a beam. In jacquard velvets, the pile warp comes directly from the bobbins in the creel. The reason for this is that the pile warp of each color is not taken to the pile surface of the velvet of the same length. For example; If the blue color is required more during weaving, that is, if it appears more on the fabric surface, the blue thread will be drawn more from the bobbin.
Pile Scarf:
It is the name given to the additional weft yarns that form the piles in weft velvets. It is connected with short yarn floats on the ground warp and is cut with an additional process to form weft pile after weaving.
Ground Warp:
It is one of the two yarn systems that form the main ground that carries the pile yarns of the velvet fabric in both warp velvets and weft velvets. In warp velvets, the ground weft connects, it does not carry the pile warps. In weft velvets, it both forms the ground weft and the basic fabric and carries the weft pile.
Ground Scarf:
It is one of the two yarn systems that make up the basic fabric that carries the pile yarns in both weft velvets and warp velvets. In weft velvets, the ground weft connects with the ground warp, it does not connect with the pile weft. In warp velvets, it both forms the base fabric with the ground warp and connects with the warp pile.
Connection Types of Pile Yarns in Velvet Fabrics:
In the weaving of velvet fabrics, pile warps connect with the ground fabric in 4 ways.
1. 'V' connection
2. 'W' connection
3. Dual W connection
4. Private links
pile length:
Pile length depends on the number of warps per inch of the fabric and the number of warps on which the pile wefts float. The length of the pile can be extended either by reducing the number of warps per inch or by increasing the number of warps on which the pile wefts float.
pile density:
Pile density varies according to the thickness of the weft, the length of the pile and the number of tufts (free spindle tufts) per unit area. Increasing weft thickness makes the pile coarser. But when all else is equal, its density increases. Long pile results in better closure of the fabric surface, giving a more dense (dense) appearance than short pile. However, the longer the pile, the smaller the number of tufting each pile weft creates. And with the same number of pile wefts per inch, an increase in density with increasing length will lead to a decrease in the number of spindle tufts (spinners). It is therefore a usual consequence that an increase in the floating number of the pile weft results in an increase in the pile weft per inch.
Changing the pile density (density) and its effects: There are different ways to change the density of the pile, and changes to the same pattern and warp can often be made simply by changing the pile per inch or the weft thickness. According to another method; the pattern is changed to obtain a different pile-to-ground weft ratio.
Frequency (solidity) of the pile:
A very important feature of these fabrics is that the pile is firmly fixed to the ground texture (for separating the spindle tufts from the surface). The density of the pile should depend mainly on the pressure of the wefts against each other. Especially in long piles, it is necessary to use large numbered wefts in order to hold the pile tightly. If fewer wefts per inch or a very long pile are desired, the required firmness is achieved by throwing the pile wefts more frequently and making so-called "tight" or "whipped" pile. A tighter weave makes it more difficult to use a thick scarf. It can be generally accepted that; In a tight pile, the drape of the fabric is damaged, on the other hand, too tightness gives the fabric a longer wear feature.
Velvets are available as both weft velvet and warp velvet. Weft velvets are woven with cotton yarn and similar yarns. Loops are formed by pushing the yarns inserted into the fabric in the weft direction to the fabric surface at the desired lengths while entering the knitting. This is achieved by properly arranging the weave of the fabric and overlapping the loop wefts, which penetrate the weave much less than the normal wefts, by hitting the stencil harder on the fabric. The pile surface of the velvet is created by cutting each row of loops in the knitting direction neatly one by one, by inserting a sharp knife attached to the end of a guide attached to a wooden stick, under the loops. If the fabric is designed in such a way that the loops formed in the rows in the warp direction are of different lengths, structures known as corduroy are obtained.
Warp velvets are obtained by two different methods. One of these is to move the loop thread between the two basic fabric layers woven on the velvet loom, passing from one to the other, and cut the loops in the middle with a movable knife as the fabric is woven.
These structures are designed like a double layer fabric; however, since the loop thread connecting the fabric layers is fed to the fabric at certain lengths, a certain distance occurs between the two layers. This system is called “face-to-face weaving”. Another system is the formation of loops on flat wire rods that are inserted into the shed like a weft and have a cutting tool at the ends. While the basic fabric remains under the wire rods, the loop threads are raised above these rods. As the wire rods are pulled through the nozzle, the loops are cut and a pile layer is formed.
Warp-loop structures are mostly applied in apparel quality velvets, wool velvets and upholstery velvets because weft velvets are very simple to touch.
The fabric class formed by carpets, rugs and similar woven structures is called “kirkit woven fabrics”. This is because, in hand weaving, after a row of loops is formed by wrapping or knotting the loop thread on the warp threads, the threads of a short-toothed steel reed called kirkit, the warp threads of the loops are formed.
It is the compression of the weft through the warp over and after the end of each loop.
Weaving systems of velvet fabrics are examined in two main groups and their subgroups.
A- Velvet production techniques,
Al- Weft velvet production,
A2- Warp velvet production;
a) Warp velvet production with a single layer system,
b) Warp velvet production with double layer system,
-Single shuttle double layer warp velvet production,
- Double shuttle double warp velvet production,
B- Cutting the pile yarns;
a) Cutting the weft pile,
b) Cutting the warp piles,
- Cutting the pile of double woven velvets,
- Cutting the pile with the pile forming rod.
VELVET PRODUCTION TECHNIQUES
We can divide the methods of obtaining velvet into two;
a) Weft velvet production,
b) Warp velvet production.
1) Warp velvet obtained with a single layer system,
2) Warp velvet obtained with a double layer system,
- Warp velvet obtained with a single shuttle system,
- Warp velvet obtained by double shuttle system.
Weft Velvet Production
The pile layer on the surface, which is the characteristic feature of velvet fabrics, is a velvet fabric formed by an additional weft yarn. Pile formation in weft velvets is obtained as a result of cutting the pile yarns with the help of a round knife.
Weft pile fabrics consist of three groups of yarn systems.
Classification of Weft Velvets
Scarf Velvets
By Yarn Type To Ground Texture Patterns To Texture Character
By Knitting
- Cotton velvet - Taffeta (1=1/1) - Velvet - Chiffon velvet
- Silk velvet - Velvet - Printed
- Twill velvet - Cord velvet
- Light fluorine velvet - Contract velvet
Instead of a looser wound loop warp and a tighter ground warp in warp velvets, weft velvets have a ground weft that provides a tighter connection with a loop weft, and both weft materials have the same properties.
Two kinds of connections are used in weft velvets.
1. “V” Connection: This connection type continues by skipping one thread. Warp threads have two kinds of movement. The first is from the bottom up, and the second is from the top down.
2. “W” Connection: In this connection type, 3 warp threads grasp the weft. This triple bond creates a better bond in the fabric compared to the "V" connection.
The factors that are important for the formation and formation of the basic ground texture and the pile surface in pile fabrics are as follows.
- Yarn properties of pile wefts
- Connection and knitting of pile wefts
- Ratio of pile wefts to ground wefts
- The state of the cutting process in the application, such as the fact that the pile wefts are completely cut or not in the fabric design, or a localized cut on the surface to achieve a fluffy pattern effect in places.
In pile fabrics, the pile yarn can be interrupted or uncut. Pile loops in weft velvets are formed by weft yarns.
The weft density is quite high in weft velvets. There are cotton velvets containing 200 weft threads per cm. However, the production amount in the machines where these fabrics are produced is low due to the dense and dense weft insertion. Although these fabrics are of high quality, they have lost their importance today due to the low production amount. On the other hand, the production of low and medium density fabrics and therefore low and medium quality fabrics is common. These are produced quickly on automatic weaving machines.
With a special weave, the weft thread is thrown from the upper surface of the fabric after a normal connection. The surface effect is not created during weaving, but by the cutting process after weaving. In special roving cutting machines, the loops in the weft direction are passed through very thin blades and the loops are cut and the fabric is formed. The cutting machine is equipped with a blade assembly wrapped around a cylinder as wide as the bench. Cutting setting is very important in cutting. In the machine, the cutters are at a height that will cut only the weft loops and not touch the basic texture, and at a density that will maintain the distance from loop to loop and the number of loops in the fabric width.
Loop wefts generally form a connection over 3, 5, 7 warp threads. They are then cut in the middle of the jump distance. Weft loops formed by connecting one or three warp threads form “V” or “W” pile loops. In weft velvets, the loops continue to the edge and are left closed, as soon as the ground texture is very tightly connected, where weft skipping occurs, the ground remains below the weft pile layer.
If a very dense pile layer is desired in the fabric, it is necessary to calculate the weft loop yarn number very high, for example 100-120 weft/cm.
Weft velvets, which have been woven with cotton yarns since ancient times, are called cotton velvets because of the weft material used. Loop rods called "Rute" are not used in weft velvets as in warp velvets. The loops hanging on the weft thread in warp velvets are suspended on the warp thread in weft velvets.
Velvet and all corduroy are weft pile velvets. It is the warp and ground weft that forms the ground in such fabrics. The soil and pile weaves are arranged separately and the drawing-in and dobby report is prepared. Pile formation in velvet fabrics in which pile is created with additional weft yarn occurs by cutting the skipping (floating) parts of the weft yarns that will form the weft pile with a round knife.
plain weft velvets
This type of weaving includes heavyweight, weft-faced cotton fabrics. It is densely covered with a uniformly short pile layer. The pile layer is formed by cutting certain wefts that float loosely on the surface after the fabric is woven. Velvetten is a shiny and thin fabric.
Matters to be considered in fabric formation;
- Basic textures used in surface and pile formation
- Ratio of pile wefts to surface wefts
When these factors are combined with weft density and finishing process; It plays an active role in pile length, density and pile strength.
The weaves that are frequently used in the formation of the main ground texture are plain and twill. The air connections are; It can be twill, satin or derived satin. In order to obtain tight pile, the number of wefts per inch should be high.
Warp Velvet Production
If the pile on the fabric surface, which is the distinctive and distinctive feature of velvet fabrics, is obtained from the pile warp, it is called warp velvet.
At least two warp beams or one warp beam and pile warps from bobbins in the creel are required to obtain warp velvet.
The characteristics of the ground warp and pile warp in warp pile velvets and their participation in the process are explained below.
floor warp
Together with the weft thread, they are the warps that form the basis of the fabric. In the single-ply warp velvet system, there is only one floor warp.
In the double layer velvet system, there are 2 ground warps.
Pile Warping
In flat velvet looms, the pile warp is wrapped in a beam. In jacquard velvets, the pile warps come directly from the bobbins in the creel. The reason for this is that different colored pile warp yarns are used in different quantities per unit length of fabric. For example, if the blue color is required more during weaving, that is, if it appears more on the fabric surface, the blue thread will be drawn more from the bobbin. The possibility of using some warp threads more or less is provided by taking pile thread from the bobbin. Warp velvet can also be produced as double velvet by passing the pile warp from an upper weave to a lower weave. After weaving, the double velvet is cut in the middle. Warp velvets “Ruten velvets They can also be touched. In the warp velvet technique, pile weavings can be produced in almost any desired pile height and in quite different appearances. For example, imitations of animal fur, silk velvet, mirrored velvet, astrakhan, etc.
Single Layer Warp Velvet Production
In velvet fabrics made with the single layer velvet technique, they are woven with two warps, the first being the taut ground and the other loosely wrapped pile warp. Pile is created by steel rods with blades at the ends, which are inserted between the pile warps when they rise. If the pile of the fabric is desired to be high, flat bars are used, if it is desired to be short, round bars are used.
This type of velvet is called “Warp Velvets Produced with the Help of Wires”. Wires are passed through the nozzle formed by the pile warps. After the pile warps descend to the lower shed position and combine with the wefts, they cover the wires in the figure. The cross-section of the wires also determines the loop shape and their height in the cross-section determines the loop heights. When the wires are pulled through the fabric, loops are formed. The special mechanism that controls the movement of the wires places the wires into the shed at the same speed as the weft thread, which is thrown very quickly, and slowly pulls it back. Having a large number of wires between two points prevents the pile loops from penetrating due to the tension on the pile warp. According to the type of fabric to be produced, the number of wires is reduced for light fabrics. For heavy fabrics, the number of wires is increased.
The piles formed on the surface of the velvet fabric are in the form of loops or bundles, depending on the structure of the wires. If the upper surface of the wires is made in the form of a knife blade, the loops will be cut and become a bundle while the wire is pulled through the fabric. If there is no cutter, loops will form. A point that should not be forgotten here is that as soon as the wire enters the high shed formed by the pile warps, the weft thread is placed in the wider shed formed by the ground warps.
Wires with circular cross-sections are used in the production of short looped velvet, while rectangular ones are used in the production of long looped velvet. The height of the wires is 1-5 mm for short pile velvets and up to 25 mm for fur and carpet imitation long pile velvets. The holes at the end of the wires provide the connection with the mechanism limbs that provide the movement of the wires. For these mechanisms, a space equal to the width of the woven fabric is needed on one side of the weaving machine. The looped velvets produced with this system are used as upholstery. Bundled velvets with cut loops are used as clothing, drapery and upholstery. There are different patterned velvets that are mostly used as upholstery and carpets.
The pile warp used during weaving is longer than the ground warp. This length varies depending on the depth of the strings and the number of strings. The pile warp can be 5-12 times longer than the ground warp. In order not to damage the pile height during weaving, the staples should only be in contact with the edge of the fabric and also with the unwinding roller and the back of the fabric in beam wrapping.
All wires are removed by pulling from left to right. For this reason, there is a danger of the loops shifting to the right. To prevent this and to create a stronger connection, the ground warp on the right of the loops should make an opposite connection.
The threads are passed through the frames from front to back according to the weaver. The loop (pile) thread is always threaded into the first frame.
Double Warp Velvet Production
The weaving system with wires used in the production of velvet fabrics is provided by mounting the movement mechanisms of the wires on the weaving looms. However, these looms occupy a lot of space, work slowly, and have some difficulties while using them.
In the double layer technique, velvets are obtained by interweaving two layers of tissue on top of each other with plain and rips texture types and interlacing the loop warp threads alternately with l upper - l lower texture. The loop distance between both fabrics is twice the height of a pile yarn and this height is kept constant by the regulator. The loops are cut right in the middle by a knife mounted on the bench and moving horizontally to the right and left on a sled.
The cutting of the loops between the two tissues takes place after the stroke of the sash is completed, that is, when the reed is in reverse and the ground warp is in tension. Because the loop cut made in an incorrect position of the card causes the formation of gradual pile ends and irregular pile height.
Double-layered velvets are woven either with a single weft or with a double weft. In double-layered velvets woven with a single weft, the weft thread is passed to both the upper and lower tissues. Thus, two tissue layers are created with a single weft system. In double weft velvets, weft threads are attached to the upper tissue by the upper weft carrier and to the lower weft by the lower weft carrier. The movement of both weft carriers is at the same speed and time. Since each weft yarn is alternately tied to l upper and l lower fabrics in single-weft double-layered velvets, 2 types of weft materials can be used with the alternating frame system.
The upper and lower textures of double-layered velvets are connected separately by connecting warps. For these connecting warps, which can also be wound in a single beam. Using two separate beams is more beneficial for the machine to operate at full capacity.
In this system, loom efficiency is high in velvet weaving. However, the surfaces formed by the loops cut in the middle are not very smooth. For this, the piles are subjected to shearing in the finishing department. It is possible to obtain patterned and motif structures in both the wire rod system and face-to-face weaving system. In both systems, any desired pattern can be obtained by controlling the loop threads with the jacquard mechanism.
The production of double warp velvet is done in two ways.
a) Single shuttle double layer velvet production,
b) Production of double-layer velvet with double shuttle.
Single Shuttle Double Warp Velvet Production
It is woven with the double layer fabric weaving technique of normal weaving looms. The pile yarn connects the upper and lower ground yarns. After the fabric is woven, the pile yarns between the two fabrics are cut and the fabrics are separated from each other.
Double Shuttle Double Warp Velvet Production
It is the system used in modern velvet making. From here, floor warp beams can be prepared separately if desired. Weft insertion is done on both fabrics at the same time. Two separate nozzles are opened on the loom, one for the upper and lower fabric.
In this system, it is possible to weave more fabrics in the same period of time compared to other systems.
Looped Velvets
It consists of the loop (pile) warp, which provides the basic texture and loops formed by the ground warp with the weft thread.
The ground warp is made of thin and highly twisted cotton yarn, as in a towel, and is kept taut. Loop (Pile) warp is looser and is made of wool, silk, rayon and cotton yarn.
Both warp threads are woven in 1/1, 1/2, 2/1 ratios. The determining factor for this is; Besides where the fabric is used, the frequency of pile warp depends on the rise and yarn count.
The formation of the loops occurs by passing long rods called “RUTE” made of steel or brass to the mouthpiece that opens when the pile warp rises.
Although the connection type of the ground warp is plain, it can also be created with textures such as R2/1, Rl/2 and panama, even twill.
During weaving, the loop warps rise over the rute and are tied back to the basic texture with one or more weft threads. The rods, which are passed in 3 or even 8 rows, begin to be pulled through the ----s formed one by one, and each drawn rod is thrown into the loop one by one to form a loop again.
Velvet textures are named according to the number of weft threads between the loops, as well as the way the pile warp binds 2 or more ground wefts (for example, 3 wefts and XNUMX wefts). For example;
Velvets with 2 Wefts: If the pile warp l is tied under the ground weft thread, it is “V” pile,
Velvets with 3 Wefts: If the pile warp is tied under l weft, over -1 weft and again under l weft, they are called “W” pile velvets.
Cut Loop Velvets
In this type of velvet, the surface is covered with cut piles. Special cutters are used in the production of cut loop velvet. To cut the loops, “RUTE”s with a sharp upper edge or when a higher pile surface is desired, sharp, flat rods with curved ends are used.
Mixed Pile Velvets
In some types of velvet, the pile is formed with the help of both round and end cutter RUTELER. In this way, a patterned appearance with both cut piles and closed loops is obtained on the fabric surface. Units with cutters on them are higher than other round units.
While leveling the tissue surface, the purpose of keeping the cut pile longer, which is subjected to a second cutting process, is to prevent damage to the closed loops.
Model (heavy upholstery) textures are woven with this technique.
CUTTING THE PILE YARNS
In the production of velvet fabric, the cutting process of the piles is important in terms of fabric quality. The pile cutting can be done while weaving or after weaving the fabric.
The cutting of pile yarns in the production of velvet fabric differs according to the production technique.
a) Cutting the piles in weft velvets,
b) Cutting pile in warp velvets.
Cutting Pile in Weft Velvets
In the production of weft pile cut fabrics; piles are created by cutting the fabric on the face side after it has been completely woven.
Pile Cutting in Warp Velvets
Two methods are used in the production of warp pile cut fabrics.
Cutting the pile of double woven velvets
In the first method, two fabrics are woven and the yarn that connects them between these two fabrics becomes the pile yarn. While the double layer fabric is moving away from the weaving area, the pile threads are cut with the help of a knife and made into two separate fabrics. These single-layer fabrics are half the thickness of the double-layer fabric and a pile surface is formed where the pile yarn is cut.
Cutting the Pile with the Pile Forming Rod
The pile forming rod has a small blade on the top edge and at one end, leaving looped pile when pulled. After some weft is fed into the fabric, this bar with a knife at one end cuts the pile warp threads. The frames move so that the pile warp threads pass over this bar. After a few wefts are thrown forward of this bar, the bar is pulled and the knife at the end cuts all the warp threads that the bar passes over. The cut yarns come to the vertical position and form the pile. After inserting a few additional wefts, the rod is placed back on the shed, weaving is continued in this way, and the rod is withdrawn after a few more wefts are thrown.
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