Comb sorter diagram machine

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Bangladesh University of Business & Technology
BUBT
Lab Report
Experiment No :11
Experiment Name :Determination of fiber length by comb sorter
diagram.
Submitted to:
Md.Khalilur Rahman
Assistant Professor
Dept. of Textile Engineering, BUBT
Submitted By:
Name: Usama bin Shahid
Program: B.sc in Textile Engineering
ID no: 17182107015
Intake: 23
Sec: 1
Date of Submission : Signature of
Teacher
Experiment No:12

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Experiment Name: Determination of fiber length by comb sorter diagram.
01.Objectives of the experiment:
fiber length by comb sorter diagram. [1]
02.Theory: Length of staple fiber is one of the most important
characteristics. In general a longer average fiber length is to be preferred
because it confers a number of advantages. Firstly longer fibers are easier
to process. Secondly, more yarns can be produced from then because there
are less fiber ends in a given length of yarn. Thirdly, a higher strength yarn
can be produced from them for the same level of twist.
2.1Definition of fiber length paramaters:
(i) Mean length: The arithmetic mean of the length of all the fibers present
in a small but representative sample of cotton, based on weight length
distribution or relative number length distribution.
(ii) Upper quartile length: The length for which 75% of all observed values
are lower & 25% higher, by wt. or by number.
(iii) Effective length: It is difficult to give a clear scientific definition for
effective length. It may be defined as the upper quartile of the numerical
length distribution from which same of the shortest fibers are eliminated
by an arbitrary construction. The fibers eliminated are those shorter than
half the effective length.
(iv) Span Length: The distance spanned by a specified percentage of the
fibers in the test board. 2.5% span length is the distance from the clamp
on a fiber beard to a point upto which only 2.5% of the fibers extend. [2]
2.2 The Shirley Comb Sorter Method:
A quantity estimate by personal judgement by which a sample of fibers
raw material is characterized as regards it’s technically most fiber
important fiber length. The Shirley Comb Sorter machine consists of a bed

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of which controls the fibers & enable the sample of fiber to be
fractionaized into the length groups.
Principle: A sample of fibers is arranged in the form of an array in the
descending order of length, and from a tracing of this array some fibre
length parameters are calculated. Two set of combs, fiber grip, needle,
aluminium depressor, velvet pod & rectangular Perspex scale are apparatus.
[3]
03. Standard atmosphere: In quality control lab,
RH% for quality room (65%+-2) and temp.
Temperature : 20 +-2 (cold countries)
27-2 c [tropical and sub-tropical] ……[4]
04. Appratus: (a) Shirley Comb Sorter (shown in fig: 01)
4.1 Sample: (a) Sample of cotton fiber (shown in fig-2)
Working Procedure: (i) A bundle of fibres prepared by one of the zoning
methods is straightened by hand and pressed into the lower set of combs
is impaled in the combs with the ends of fibers protruding as illustrated in
the left-hand side.
(ii) The end of the bundle is straightened by gripping the ends of the
outermost fibers with a wide clamp & withdrawing them a few at a time.
(iii) The whole sample is then transferred in this way, a few fibers at a
time, to position at the other ends of the comb and placed there so that
the fiber ends coincide with the first comb.
(iv) The sample is pressed down into the bottom combs and the top
combs are then lowered onto the sample.

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(v) The rear combs are moved out of the way are at a time until the ends
of the longest fibers are exposed.
(vi) The exposed fibers are then removed by the grip and laid on a black
velvet pad. The next comb is then removed, so exposing the fibers which
constitute the next length group and these are removed and laid next to
the first set of fibers, making sure that all the fibers are laid with a
common base line.
(vii) Then trace the outline of the fiber array prepared on a sheet of
translucent paper.
6.Curve:
Here, OC = 1 2 OA OQ = 1 4 OP OL = 1 4 ON Maximum length, OA = 4cm
= 40mm
Upper quartile length OQ’ = 3.9cm = 39mm
Effective length, LL’ = 3.9cm = 39mm
Modal length, PP’ = 1.8cm = 18mm
Short fiber length NN’ = 1.7cm = 17mm
American fiber/Staple = 0.91 * Effective length = 0.91*39 = 35.49mm Indian
Staple = 0.85*Effiective length = 0.85*39 = 33.15mm

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Process Curve: (i) C is the middle point of OA i.e. OC = 1 2 OA (ii) From
C draw CP’ parallel to OB to cut at P’ (iii) Drop the perpendicular PP’ (iv)
Mark of OQ equal to 1 4 OP & draw the perpendicular QQ’ (v) D is the
mid point of QQ’ (vi) From D draw DN’ parallel to OB to cut the
curvature N. (vii) Drop the perpendicular N’P (viii) Mark of OL equal to 1
4 ON (ix) Draw the LL’ at perpendicular which is the effective length.
07.Calculation of fiber length according to rectangular scale:
Mx. Length, OA = 40mm
Upper quartile length, QQ’ = 3.9CM = 3.9*10mm = 39mm
Effective Length, LL’ = 3.9cm = 3.9*10mm = 39mm
Modal Length, PP’ = 1.8cm = 1.8*10 mm = 18mm
Sort fiber length, NN’ = 1.7cm = 17mm
American fiber/staple = 0.91*Effective length
= 0.91*39 = 35.49 mm
Indian Staple = 0.85*Effective length
= 0.85*39 = 33.15 mm Short fiber (%) = 18𝑚𝑚 120𝑚𝑚
* 100% (𝑁𝐵 𝑂𝐵 ) Result: Maximum length = 40 mm
Upper quartile length = 39 mm
Effective length = 39 mm
Modal length = 13 mm
Short fiber length = 17 mm
Short fiber (%) = 15%
09.Conclusion: After completing this experiment, we have known about
fiber length and have acquired ability to determine fiber length by using
comb sorter diagram and this experiment will be helpful in our future job
life.
10.Reference:

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[1], textilelearner.blogspot.com
[2], textileanalysis.blogspot.com
[3], dilutestudents.blogspot.com
[4], BUBT TTQC Lecture Sheet, KR, Fall 19-20
[5], TTQC Lab, BUBT