Fibre Length Technique
Fibrogram and Sorter Diagram
The fibro gram shows the length of the fibre on the x-axis and the
proportion of fibre on the y-axis. In contrast, the sorter diagram shows
the proportion of fibre on the x-axis and the length of the fibre on the
y-axis. The sorter diagram arranges the fibers horizontally from the
longest to the shortest length. If we superimpose the sorter diagram
and the fibro gram, we get the fibre diagram superimposition of both.
This difference is due to the two assumptions of length biasness and
folding of the fibers.
Uniformity Ratio
The uniformity ratio is the ratio of the 50% span length and 2.5% span
length. If the uniformity ratio is less than 40%, the quality of the fibre is
poor. We can calculate the uniformity ratio of cut polyester staple fibre
or any cut fibre. The maximum uniformity ratio for cotton is 50%, and
for polyester cut polyester of equal length, we can reach up to 0.5128.
Calculation
We can calculate the value of the uniformity ratio and the uniformity
index with simple formulas. For example, if the 50% span length of
cotton is 13.5mm, and the uniformity ratio is 45%, the 2.5% span length
in mm is 30mm.
Fibre Length Measurement in Textiles
Let's start with the Uniformity Ratio and Uniformity Index for polyester
fibres. The Uniformity Ratio is 51.28%, which is the theoretical
Uniformity Index. However, in reality, the Uniformity Index for
, polyester fibres is 100% for which the mean fibre length is equal to the
upper half mean length. Testing the fibre in a fibrogram will not give
the exact values due to variations.
Wool fibers are different from cotton fibres, and we cannot measure
their length using a fibro gram. The Wool Fibre Diagram Machine is
used to measure wool fibre length, which works on the capacitive
principle. The combed wool fibre is taken for measurement after
removing the grease content, and the length is measured using the
Wira Fibre Diagram Machine. The fibres are gripped and pulled through
the measuring slot manually, and the machine measures the
capacitance as the draw passes through the slots. The mean length is
calculated using the cumulative frequency diagram, and the
capacitance is proportional to the mass of the material.
There are two different versions of the fibrogram machine. The first
version is the manual Wira fibre diagram machine, which requires the
draw to be prepared by hand and plotted manually. The advantage of
the Wira machine is that it gives a clear idea of the actual length of the
fibre. However, this technique cannot be used for cotton because the
fibres are too short and have high variability. The second version is the
automatic Almeter, which is the automatic version of the Wira machine
with a little modification. The modification is the preparation of the
sample, which is known as the fibroliner. The fibroliner prepares the
sample automatically using a bottom comb and a top comb. The fibres
are arranged randomly in the bottom comb, and the fibroliner grips the
fibres repeatedly, taking them with a very small length of a few
Fibrogram and Sorter Diagram
The fibro gram shows the length of the fibre on the x-axis and the
proportion of fibre on the y-axis. In contrast, the sorter diagram shows
the proportion of fibre on the x-axis and the length of the fibre on the
y-axis. The sorter diagram arranges the fibers horizontally from the
longest to the shortest length. If we superimpose the sorter diagram
and the fibro gram, we get the fibre diagram superimposition of both.
This difference is due to the two assumptions of length biasness and
folding of the fibers.
Uniformity Ratio
The uniformity ratio is the ratio of the 50% span length and 2.5% span
length. If the uniformity ratio is less than 40%, the quality of the fibre is
poor. We can calculate the uniformity ratio of cut polyester staple fibre
or any cut fibre. The maximum uniformity ratio for cotton is 50%, and
for polyester cut polyester of equal length, we can reach up to 0.5128.
Calculation
We can calculate the value of the uniformity ratio and the uniformity
index with simple formulas. For example, if the 50% span length of
cotton is 13.5mm, and the uniformity ratio is 45%, the 2.5% span length
in mm is 30mm.
Fibre Length Measurement in Textiles
Let's start with the Uniformity Ratio and Uniformity Index for polyester
fibres. The Uniformity Ratio is 51.28%, which is the theoretical
Uniformity Index. However, in reality, the Uniformity Index for
, polyester fibres is 100% for which the mean fibre length is equal to the
upper half mean length. Testing the fibre in a fibrogram will not give
the exact values due to variations.
Wool fibers are different from cotton fibres, and we cannot measure
their length using a fibro gram. The Wool Fibre Diagram Machine is
used to measure wool fibre length, which works on the capacitive
principle. The combed wool fibre is taken for measurement after
removing the grease content, and the length is measured using the
Wira Fibre Diagram Machine. The fibres are gripped and pulled through
the measuring slot manually, and the machine measures the
capacitance as the draw passes through the slots. The mean length is
calculated using the cumulative frequency diagram, and the
capacitance is proportional to the mass of the material.
There are two different versions of the fibrogram machine. The first
version is the manual Wira fibre diagram machine, which requires the
draw to be prepared by hand and plotted manually. The advantage of
the Wira machine is that it gives a clear idea of the actual length of the
fibre. However, this technique cannot be used for cotton because the
fibres are too short and have high variability. The second version is the
automatic Almeter, which is the automatic version of the Wira machine
with a little modification. The modification is the preparation of the
sample, which is known as the fibroliner. The fibroliner prepares the
sample automatically using a bottom comb and a top comb. The fibres
are arranged randomly in the bottom comb, and the fibroliner grips the
fibres repeatedly, taking them with a very small length of a few
