According to the Textile
Institute the fiber migration may
defined as the change in distance of a fiber or filament from the axis of a
yarn during yarn production process.
PARAMETERS FOR FIBER
MIGRATION:
A)
Staple Length of Fiber: With the increase of staple
length migration will also increase.
B)
Tension: With the increase of tension of fiber
migration will also increase.
C)
Mode of Spinning:- Fiber migration in yarn depends on
the methods of manufacturing processes.
FIBER MIGRATION IN YARN:
If a particular fiber were to
process into a variety of staple and continuous filament structures, textured
and un textured, one could expect substantially different characteristics in
each yarn. To fully understand or predict the performance of yarns, it is
necessary to explore the structure of yarn in details.
The study of fiber geometry (spatial
configuration of fibers) in yarn was initiated in the early 1950’s by Morton
and Yen, who developed a fiber tracing technique to indicate the position of
individual fibers relative to the fiber axis. A small portion (less than 1 % by
weight) of dyed fiber is thoroughly blended with similar but un dyed fiber
before conversion into yarn. The yarn is immersed into a liquid media of the
same refractive index as that of the fibers, causing the un dyed fibers to
become practically transparent and allowing the dyed (tracer) fiber to be
observed and scanned microscopically.
The successive segments of the fiber
or filament being scanned are usually shown to be positioned in various annular
zones in the yarn structure from core to surface to core in migration patterns
of various periodicities. The term fiber migration is used to describe the
relative fiber movement during processing and the position of fiber in final
yarn structure. Fiber migration, which is expressed by various parameters and
indices, depends on many fiber
properties , characteristics of the fiber assemblages, and processing
IDEAL MIGRATION OF FIBER IN
YARN:
The ideal migration pattern is
defined as one in which the fiber migrates regularly & uniformly from
outside to the center of the yarn and the back to outside in such a way that
the density of packing of fibers in the yarn is constant throughout the yarn.
B. Measurement of Fiber Migration by Riding’s Experiment:
From the above ratio r/R he measured the amount of fiber migration of colored filament in yarn.
This was developed by Morton
& Yen, who developed a fiber tracing technique to indicate the position of
individual fibers relative to the yarn axis. A small proportion (less than 1%
by weight) of dyed fiber is thoroughly blended with similar but un dyed fiber
before conversion into yarn. The yarn is immersed into a liquid media of the
same refractive index as that of the fibers, causing the un dyed fibers to
become practically transparent and allowing the dyed (tracer) fiber to be
observed and scanned microscopically and thus the migration is measured. Here
the colored fiber is called tracer fiber.
B. Measurement of Fiber Migration by Riding’s Experiment:
Riding used a different technique to estimate
the measurement of migration. He did it by measuring the relative radial
positions.
From the above ratio r/R he measured the amount of fiber migration of colored filament in yarn.
He used the liquid in which the
yarn is immersed and which had the same refractive index as that of viscose and
nylon (i.e. continuous filament yarn). He used a mirror to carryout the
experiment for analytical analysis. He has used one black filament in the yarn
to study the migration behavior. He carried out experiments at an interval of
half a turn of twist & 200 such measurements were taken to get the result.
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