It is the winding of the fibers around an axis (yarn axis) on each other in order to provide resistance against the tension forces that the yarn will undergo during fabric formation.According to the yarn numbering system used, the amount of twist determined in 1 meter or 1 inch, that is, in a unit measure, is one of the most important factors affecting almost all the properties of the fabric, especially the strength of the yarn and, accordingly, the fabric's strength, touch, appearance and economy.The strength of the yarns produced from staple fibers is provided by applying a certain amount of twist.Twist is expressed as S or Z according to the direction of the applied torsion. Under normal conditions, the yarns are always Z twisted (If the spirals or helixes that occur in the single ply yarn held vertically are in the right direction (right) in the middle of the letter Z, or if they are held at the ends and turned to the right (clockwise) by the right hand. If it is rotated (in the direction of) straightening and losing its strength, the yarn is Z-twisted). counterclockwise) turns it straight and loses strength, then the yarn is S twisted.)
It is very important to know the number and direction of twists in the yarn. The amount of twist to be given to the yarn in yarn formation depends on the fineness of the fiber, its length, yarn count and the place where it will be used. The amount and direction of twist to be given to the yarn varies depending on the type of yarn and the place it will be used (weaving, knitting, crepe).
Knitting yarns are low twisted yarns and crepe yarns are high twisted yarns. Weaving yarns have higher twist than knitting yarns. Various fabric effects can be achieved by changing the twist amount and direction of the yarns. Some of these are visible, some change the behavior of the fabric, and some are mechanical.
For example; In the weaving of a fabric, two different types of yarns with both “S” and “Z” twists are used in the warp, and therefore, a patterned fabric is obtained because of the reflection of the rays in different ways from these yarns. Since the yarn's ability to take dye will change with the number of twists, the number of twists must be determined correctly. The yarn with high twist count takes less dye than yarn with low twist count. Therefore, if yarns with different twists are included in a fabric, there will be tonal differences called abraj in the fabric. Yarns made of staple fibers must be twisted in order to be strong. Yarn strength increases in proportion to the amount of twist given. The higher the twist, the higher the strength of the yarn. However, after a certain critical point, although the amount of twist increases, the yarn strength decreases.
yarns are also produced. The amount of twist to be given to a yarn is selected according to the future use of the yarn and the fiber length. As the fiber length increases, the twist requirement will decrease. The degree of twist is generally divided into two;
OPEN TWIST :
It is given to knitwear (knitting) yarns. Since the resistance to be encountered by the yarns in the knitting machine is relatively low, the amount of twist on the knitwear yarn is lower than on the weaving yarn. Therefore, knitwear yarn strength is lower than weaving.
CLOSED TWIST :
It is given to weaving threads. Since the load on the warp yarns is quite high in the weaving loom, higher twist is given to the weaving yarns compared to knitting. Therefore, the strength of weaving yarn is higher than that of knitwear. It should not be forgotten that as the amount of twist increases, the yarn will become harder and the production cost will increase.
Benefits of twisted yarn count detection:
1-It gives an idea about the physical thickness and thinness of the yarn.
2-It is an important element in determining the yarn cost.
3-It gives an idea about the covering of the yarn on the fabric.
4-It is an effective factor in fabric designs
Bends by number of bends
1.Soft twist
2.Normal twist
3..Hard twist
4.Crepe twist
5.Fantasy twist
Twists according to yarn count
1.Single-ply twist
2.Two-fold twist
3-Multi-layer twisting (cable twisting)
Purpose of Multifold Twisting :
1- Adding strength to a single ply yarn
2- Obtaining threads in various appearances
3-Creating a different look and effect on the fabric
4-To obtain yarns with multiple layers and different structures.
Purpose of Finding the Number of Twists in a Ply Yarn :
A ply twisted yarn is formed by combining two or more single yarns by twisting. Twisting of two single-ply yarns is called doubling or doubling.
Twisting two or more ply yarns together is also called multi-ply or cabling.
Folding, It is called making the yarns parallel to the neck without being twisted.
Twist; is the number of turns per unit length of thread. Twist; It is applied to give the fibers a permanent appearance, to increase the contact surface with each other, and to keep the fibers together. With twisting, parallel fibers are converted into helical form and the yarn gains strength.
The number of twists is expressed as the number of turns (spiral) per unit length on the twisted yarn. The number of spirals made by the fiber per unit length gives the number of twists. By using the twist factor, information about the twist characteristic of the yarn can be obtained without knowing the yarn number. The number of twists is determined by the raw material used and the place where the yarn is used.
Number of twists;
1-The touch and attitude of the fabric,
2-thread strength,
3-yarn volume and covering factor,
4-Strength and flexibility of the fabric,
5- pilling feature of yarn and fabric,
6-Permeability of the fabric,
7-It affects the service life of the fabric.
Detecting Twist Direction of Twisted Yarn:
In addition to the twist given to the yarn, its direction should also be known. The direction of twist depends on the direction of rotation of the spindles on the spinning machine. If the spindles rotate clockwise, right twist (Z), if counterclockwise, left twist (S) is given to the yarns. In order to detect the twisting direction of the yarn, one end of the yarn is held between the fingers and hung downwards; If the traces (helices) on the yarn are oriented in the right direction, the yarn twisting direction is the right direction. Again, if the helices on the yarn are parallel to the middle line of the letter Z, the twisting direction is to the right. If the twist helices on the yarn are oriented to the left and are parallel to the middle line of the letter S, the yarn twist is left twist.
The direction of the twist in the yarn does not affect the strength value. The effect of the twist direction manifests itself in terms of reflecting the light differently on the fabric surface.
While the twist direction of the yarns produced in the ring spinning system is clearly visible, the twist direction cannot be clearly understood visually, although there is twist in the yarns produced in the OE-Rotor spinning system.
S or Z twist in single yarn twist (symbol of single yarns), SZ, ZS, SS or ZZ twist in plied yarn twist (twist direction and symbols of ply yarn); ZSZ or ZZS twist directions can be selected in cable yarn twisting. If the twist direction of the yarns to be twisted is the same as the twist twist direction, it is called twist on twist. It creates a hard thread.
Twist directions in the yarn
S twist
If the spirals or helices formed in a single ply yarn held vertically are in the right direction (left) in the middle of the letter S, or if it is held at the ends and turned to the left (counterclockwise) by the right hand, it straightens and loses strength, then the yarn is S twisted.
Z twist
If the spirals or helices formed in a single ply yarn held vertically are in the right direction (right) in the middle of the letter Z, or if it is held from the ends and turned to the right (clockwise) by the right hand, it straightens and loses its strength, then the yarn is Z twisted.
It is very important to know the number and direction of twists in the yarn. The amount of twist to be given to the yarn in yarn formation depends on the fineness of the fiber, its length, yarn count and the place where it will be used. The amount and direction of twist to be given to the yarn varies depending on the type of yarn and the place it will be used (weaving, knitting, crepe).
Knitting yarns are low twisted yarns and crepe yarns are high twisted yarns. Weaving yarns have higher twist than knitting yarns. Various fabric effects can be achieved by changing the twist amount and direction of the yarns. Some of these are visible, some change the behavior of the fabric, and some are mechanical.
For example; In the weaving of a fabric, two different types of yarns with both “S” and “Z” twists are used in the warp, and therefore, a patterned fabric is obtained because of the reflection of the rays in different ways from these yarns.
Since the yarn's ability to take dye will change with the number of twists, the number of twists must be determined correctly. The yarn with high twist count takes less dye than yarn with low twist count. Therefore, if yarns with different twists are included in a fabric, there will be tonal differences called abraj in the fabric. Yarns made of staple fibers must be twisted in order to be strong. Yarn strength increases in proportion to the amount of twist given. The higher the twist, the higher the strength of the yarn. However, after a certain critical point, although the amount of twist increases, the yarn strength decreases.
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