TWIST CONTROL
Twist control in filament yarns; It is done to control whether the filament yarn is produced at the twist values determined in the production plan. If yarn is produced at the determined twist values, production continues. If it is not produced, the machine settings are reviewed and yarn is produced at the twist values in the production plan.
İTwist in yarn
In filament yarns, twisting is done to add strength to the yarn by twisting the filament yarn around its own axis.
Tan of the Twistımı
Twist; It is the number of turns of a meter or an inch long thread around its axis. Filament fineness, length and softness affect the amount of twist. The number of twists of the yarn in weaving; weft, warp, knitwear and hand knitting yarns, clothing, home textiles, etc. depending on its use in the fields. The number of twists to be given to the yarn;
1-Fiber properties used,
2-The area where it will be used,
3-It changes depending on the properties of the yarn.
Aspects of Twist
Twist in a yarn is expressed by the twist direction and the number of twists. Yarns can be twisted in two ways as right (Z) twist or left (S) twist direction. The twist direction differs in the woven and knitted surfaces. The number of yarns to be used in production and twist directions must also be the same.
1-Right twist (Z twist) control:
When the yarn is held vertically and examined, if the spirals or ellipses occurring in single-ply yarn fibers are in the direction of the middle line of the letter Z, this yarn is right (Z) twisted. A Z-twisted effect (appearance) occurs when the spindle rotates clockwise, that is, to the right.
2-Left twist (S twist) control:
When the yarn is held vertically and examined, the spirals or ellipses occurring in single-ply yarn fibers are left (S) twisted in the direction of the middle line of the letter S. An S-twist effect (look) is created by turning the spindle counterclockwise, that is, to the left. One of the twist measuring devices designed and produced in different ways is shown below.
Finding the bending direction by handın way:
1-A short yarn sample is held between the thumb and forefinger of both hands.
2- Bend to the right with the right hand.
3- If the yarn twist is opened and the yarn loses its strength or the fiber becomes parallel at the ends, it is a “Z” twist.
4- If there is an increase in the twist of the yarn, it is “S” twist.
Twist Opening Method İle Twist Control
It is based on the principle of opening the twist by turning the twist in the yarn in the opposite direction. The number of twists at the moment when the yarn twist is fully unfolded gives the total twist of 1 meter. Twist in meters and inches is calculated taking into account the length.
Twist measuring deviceı;
It consists of a fixed yarn clamping jaw and a clamping jaw that can rotate in two directions and move in the direction of the yarn. The rotatable jaw is driven by a motor and transmits the number of revolutions to a counter. The number of turns of the moving jaw can be counted by a counter. The distance between the jaws can be adjusted to 25-250 mm. Yarn twist is the number of turns per unit length of yarn. Therefore, the thread length must be set correctly during the measurement. In the device, there is an arrangement that will take the elongation arising from the opening of the twist and a mechanism that can keep the yarn at a certain tension between the jaws. There are weights according to the number of yarn that will provide this tension.
If the thread is placed loosely between the jaws, an excessive length of twist will be measured, and when it is too tight, a shorter distance twist will be measured. It is also possible that the device will not work if the strained sample is connected. The tension value to be calculated according to the yarn number whose twist is to be measured is obtained by placing the required amount of weight on the fixed jaw side of the twist measuring device. Moving
The needle moves when the jaw starts to turn in the direction to take the twist of the yarn. The needle returns to its original position after the thread is completely unwound and begins to twist in the opposite direction. The value read in the counter gives the number of twists.
Number of Twists per Meterısı detection
The value taken from the untwisting device gives the number of twists per 1 meter of yarn and is stated as “twists per meter”. The number of twists per meter is commonly used to indicate the degree of twist.
The number of twists per meter in filament yarns is from 20 to 40. Low twist is sufficient for these yarns.
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. Doubling is called making the yarns parallel to the neck without being twisted.
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.
Twists according to yarn count
>> Single fold twist
>>Two-fold twist
>> Multilayer twisting (cable twisting)
Bends by number of bends
>> Soft twist
>> Normal twist
>> Hard twist
>> Crepe twist
>> Fancy twist
The above-mentioned twist types are applied in order to obtain new and different products by changing the flexibility, strength, brightness, covering power and permeability of the yarn by giving different appearances to the yarn. The common elements of twist measuring devices used in determining the number of twists in ply yarns are listed below.
1-Twist direction adjustment button (Z twist, S twist)
2-Engine speed adjustment knob
3-Counter reset button
4-Twist measurement setting selection according to the coefficient of the yarn
5- “Start” / test start button
6-“Stop” / test stop button
Twist; is the number of turns per unit length of thread. Therefore, the thread length must be set correctly during the measurement. If the yarn is placed loosely between the jaws, an excessive length of twist will be measured, and if it is too tight, a shorter distance twist will be measured. In order for the thread length to be optimal, a certain tension value must be given to the thread.
Detecting the Twist Direction of the Ply Yarn
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.
Measurement of twist of double-ply yarns
The difference between the measurement of single and double yarns is at the end of the test. Single-ply yarns can be measured by the on/off method, taking advantage of the twist elongation principle. For this, the device must operate automatically. In other words, the twist will be opened with the operation of the device, and the length of the untwisted yarn will increase. If the yarn that has been completely untwisted continues to be rotated in the same direction, it will start to twist in the opposite direction of its first twist. The length of the yarn that is twisted again will be shortened and when it reaches its original length, the device will automatically stop by means of sensors. In double-ply yarns, on the other hand, since fiber-fiber bonds occur between yarn layers, yarn lengthening and shortening in the opposite case caused by untwisting is not healthy. For this reason, after the yarn twist is opened a little, a pointed tool (needle) should be passed from the end of the left jaw and slowly moved towards the right head, the measurement should be continued at a slow speed and the motor speed should be reduced to zero in order to avoid mistakes in the last turns of the twist and the last turns should be opened by manually turning the right jaw. When the yarn plies are completely separated from each other, 2 times the value read from the meter (read value x 2) is the twist amount of the plied yarn in turns/meter.
Purpose of Finding the Number of Twists in a Twisted Yarn
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.
1-Number of twists;
2-The touch and attitude of the fabric,
3-Thread strength,
4-Thread volume and covering factor,
5-Strength and flexibility of the fabric
6-Plumping feature of yarn and fabric,
7-Permeability of the fabric,
8-It affects the service life of the fabric.
The purpose of the experiment; It is the determination of the twist amount of single and double ply ring yarns, spun from natural and artificial, staple or filament fibers, by on/off method. With this method, the amount of twist of the yarns produced by the open-end rotor spinning technique cannot be determined. 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.
A twist is given to the yarn in each turn of the twisting element. Twist is expressed by the number of turns per unit length (such as laps/m, laps/inch, laps/cm). The amount of twist to be given to the yarn varies depending on the type of yarn (cotton, polyester, viscose, etc.), the place where it will be used (weaving, knitting, etc.) and the spinning machine used (ring, rotor, air-jet, friction, etc.). The end product (shirts, trousers or outerwear, work wear, women's dresses, etc.) in which the yarn will be used also determines the required strength value in the yarn and thus the twist value. yarn strength increases in proportion to the amount of twist given. Increasing the amount of twist increases the yarn strength up to a certain point. This happens as the spaces between the fibers decrease and the fiber-fiber adhesion increases.
After the optimum twist point, the fiber length that contributes to the yarn strength decreases, the tension on the fibers increases, fiber breaks, slips are seen with the renewal of the fiber-fiber friction, and the yarn strength decreases. If the twist is continued to increase, the yarn breaks as a result of these events.
In addition to the twist given to the yarn, its direction should also be known. The yarn can be twisted in the “S” or “Z” direction.
Purpose of Twisted Yarn Count Control
It is to determine whether the yarn is produced at the desired yarn count.
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.
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