Fiber length values;
It is effective on the spinning performance of the yarn, yarn fineness, unevenness, strength, and handling.
As the percentage of short fiber increases, the following problems are encountered in the production stages.
1-Thread breaks increase.
3-Nope amount increases.
4-The unevenness increases.
6-The waste rate increases.
Length in Wool Fiber
Length is one of the important properties for wool fiber. Length and fineness directly affect the bending and production.
When talking about length, the distance between the two ends of a fiber comes to mind. The unit of length is mm.
In wool, fine fibers are short and thick fibers are long.
In addition, the average fiber length is given importance in determining the quality classes in wool.
The longer the fiber, the greater the contact surface during spinning, which increases the holding force and increases the strength.
In addition to the length, the distribution of the length is also very important.
The narrower the length distribution covers, the more homogeneous yarn can be obtained.
Before the wool fiber is turned into yarn, it must have certain properties.
In order for the fiber to be spun, its length must be at least 10 mm.
wool fiber quality is expressed with ''s''. Micron (µ) equivalents of ''s'' values are given below;
S Values Average diameter in microns (µ)
80's 18.8 micron
70's 19,7 micron
64's 20,7 micron
60's 23,3 micron
58's 24,9 Micron
56's 26,4 Micron
50's 30,5 Micron
48's 32,6 Micron
46's 34,0 Micron
44's 36,2 Micron
40's 38,7 Micron
36's 39,7 micron
The higher the 's' degree, the finer the fiber.
It is difficult to decide the length of the wool fiber. Because wool fiber is crimped due to its structure. Therefore, there are two lengths of wool fiber.
Length of a single fiber measured without straightening the folds
Types of lengths measured in an elongated form until the folds are smoothed
Two methods are used to measure the length of the wool fiber:
1-Single fiber length measuring method
2-Determination of length in bundled fibers
Length Measurement in Wool Fiber
Single fiber length measuring method
In the single fiber length measurement method, the fatigue of the worker is prevented with the help of semi-automatic tools. it also saves time.
It is somewhat difficult to determine the wool fiber length.
Because wool fiber is naturally curled and some effort is required to straighten it.
With this method, individual lengths of fibers are measured.
Methods used to measure the length of wool fiber:
Length measurement with the forceps method
In this method, 2 forceps, 1 ruler, 1 black velvet plate are required for length determination.
The ends of the fibers taken from the sample 2 are pulled until the folds of the forceps are removed and the length is measured directly on the ruler.
A value is obtained by averaging the measured lengths.
Although it is a method that requires less equipment, it is a method that takes a lot of time of the worker.
Length measurement on glass and velvet coated plate
This method can be applied to all staple fibers except those that naturally contain many folds.
A small amount of white vaseline, paraffin or glycerine water is applied on a glass plate.
A single fiber scale is placed flat on the board and measured.
This process is repeated for each fiber to which the experiment will be applied.
A value is obtained by averaging the measured lengths.
Single fiber length measurement method is mostly used for wool and similar fibers because they are long fibers.
Length measurement with the Wira device
The Wira length measuring device is suitable for measuring the length of wool and bristle fibers.
It is measured semi-automatically under controlled pressure.
A large number of single fibers can be measured in series.
Wira length measuring device consists of an endless screw and detector.
The fiber lot whose length is to be determined is placed on a black background.
It is covered with a glass plate so that the bottoms of the fibers remain outside.
From here, the fibers pulled one by one with the help of a forceps are passed between the guide wires (5) of the device and under the pressure plate (3).
With the thumb of the left hand, the pressure plate (4) is pressed down to ensure the rotation of the worm screw (8). The forceps holding the fiber are placed lightly in the slot of the worm screw.
Meanwhile, the detector wire (6) goes down and stays just above the mercury in a mercury-filled chamber.
In this way, the tip of the collet is placed between the thread of the rotating worm screw (8).
With the rotational movement of the threaded screw, the tip of the collet starts to move to the right with the fiber.
As soon as the fiber passes through the pressure block, the detector wire contacts the mercury and the movement of the mercury stops.
At this time, one of the keys on the key scale on the worm screw is lifted upwards by lifting the clamp upwards.
With the help of the keys, the length of the fiber is automatically measured and recorded on the number indicator on the drum of the device.
In this way, the length is measured repeatedly.
With the help of this device, it is possible to measure the average length of 500 fibers per hour.
The key table is arranged at 0,5 cm intervals.
When the measurements are completed, the amount of fiber that hits 0,5 cm intervals is recorded in the drum of the device.
Length measurement in bundled fibers
Length measurement in bundled fibers is made by three different methods.
Measuring the tuft length in fleece
In this method, the tuft length of animal fibers in the form of fleece tufts is determined.
A ruler is placed on a velvet-covered board.
The tuft is laid by spreading and pressing on the velvet along this ruler.
Care should be taken not to stretch the strand so as not to disturb the normal folds of the wool.
The length of the tuft is measured. When measuring tipped fleece, that point of the ruler is brought to the tuft base and the length is measured from the point in the middle of the distance between the pyramid-shaped base and the top.
In a tunic, they are bundles of naturally clumped fibers.
EIt is the average length of the tuft lengths in the normal state without the curvature and stretching of the fibers.
The tip of the tufts is a pointed end fleece.
Length measurement with sorter device
A sample of 1000 g is taken from the fiber whose fiber length is to be determined and it is made as parallel as possible by hand.
20 tufts are taken from different points of the fiber pile whose length is to be measured. These tufts are blended.
Samples are prepared by blending.
This mixture obtained is combed with a hand comb and spread on the table by placing it on top of each other.
Half of the fiber samples taken are thrown out each time and turned into a sample of maximum 1 g, placed on the first of the two comb groups of the sorter comb and pushed between the combs with the pressure fork.
First, the fibers whose ends have come out of the outermost comb are pulled with the help of the special pliers of the tool and placed on the second comb group.
After that, the outermost first comb is dropped and the fibers extending out from between the teeth of the second comb are pulled with the help of forceps.
The second comb group is laid on it in such a way that its ends align with the previously placed fibers.
Then the second comb is dropped and the same process is done.
This process is continued until there is no fiber left on the first card group.
In this way, the ends of the fibers collected on the second comb group are aligned as much as possible.
By starting the second combing in reverse, the fibers are transferred onto the first comb group by combing again.
Scanning in this way is repeated several times, so that the ends of each fiber in the sample are completely aligned.
In this case, the teeth of the comb group are started to be dropped from the opposite side, and the fibers between the two combs are pulled with pliers and arranged separately in successive groups on the velvet plate floor according to their lengths.
In this way, stapling is also carried out.
The lengths of the fiber groups are measured with a ruler and their weights are measured by weighing them with a balance.
The obtained values are recorded in a form prepared by the enterprises used for this purpose.
It is called parallelizing a strand of fiber taken to show the fiber length and making it similar to a staple diagram.
Effect of staple length on yarn:
Staple length is important for yarn evenness and quality.
Thin, high quality, smooth surfaced yarns are obtained from long fibers, and coarse and low-quality yarns are obtained from short fibers.
Length measurement with Almeter (Almeter) device
This method takes advantage of the electrification properties of fibers and measures fiber length by changes in electric currents.
It provides an objective measurement of the length of wool and other hair-based animal fibers.
The most important feature is the use of fiber for length distribution. The device consists of four main groups.
1-Scanner and accessories,
2-Electronic measuring unit,
5-It is a voltage regulator.
The fiber sample to be determined for length is placed on the combed part of the device.
Here, some combed parallel fiber bundle is removed from the carding part together with the grid on which it is located.
Combed fibers are brought to the part of the machine where the actual measuring process will be carried out and placed between two transparent surfaces there.
By pressing the start button, the fibers pressed well between the two transparent surfaces enter the machine.
Since the necessary adjustments are made in advance on the computer connected to the machine, the length parameters are electronically measured and recorded as the sample passes through the condenser.
The histogram and numerical values expressing the fiber length appear on the screen.
If desired, the result is taken as a printout and an evaluation is made.