By Gerald Henrici, President,
Aspex Inc., New York
Since the early days of the man-made fiber
industry, it has been recognized that the spinnerette is
one of the single most important components in
insuring successful production. Fiber uniformity,
essential for end-user applications, rests on capillary
geometry.
Over the years, much effort has been spent to try
to control spinnerette quality from the time of its
initial manufacture, through the demands of day-today
production. In recognition of this, spinnerette
inspection has played a key role in achieving
consistent high quality fiber production.
Inspection Methods
Many different inspection technologies have
been employed. These can broadly be classified into
two categories: contact and non-contact inspection.
In the case of contact inspection a probe is
pushed against the spinnerette surface and air or oil is
then pumped through the capillary. Deviations in the
expected flow are recorded.
Although these methods try to approximate the
flow of polymer through the capillary, they are often
impractical in a production environment due to the
difficulty in maintaining a constant viscosity of the
oil or air (temperature and/or humidity dependent),
leakage of the seal to the spinnerette surface, and the
slow, sometimes messy, nature of the inspection. In
addition, due to the fact that a probe must firmly
touch the surface, there exists the possibility that the
inspection process itself may damage the spinnerette.
In recent years, non-contact systems employing
video based microscopes have been introduced with
remarkable success. These systems provide rapid and
repeatable measurements involving a minimal
amount of spinnerette handling. In addition a wide
variety of measurements impossible with other
techniques are easily available.
The SpinTrak System
An example of such a system employing state-ofthe-art
vision technology, the SpinTrak family of
spinnerette inspection systems is designed
specifically to provide synthetic fiber producers with
unmatched speed, accuracy and repeatability for
spinnerette inspection.
The system is a robust, user-friendly spinnerette
measurement device designed to be used by both engineering and production personnel alike. It features fully automatic inspection of capillaries as
small as 0.020mm to as large as 6mm in diameter.
Three SpinTrak models are available to
accommodate round spinnerettes as small as 10mm
in diameter to rectangular spinnerettes as large as
500mm x 5500mm. An unlimited number of
capillaries on each spinnerette can be inspected at
rates from 0.3 seconds to 1.25 seconds per capillary.
In the following paragraphs we will illustrate
some examples of the measurements possible and
their impact on fiber quality.
Back light Inspection. For each capillary five basic measurements are made:
These measurements are good for finding defects such as dirt and out of round capillaries and surface damage caused by the impact of tools or poor spinnerette handling:
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Spinnerette manufacturing defects such as
capillaries that are not drilled perpendicular to the
surface can be detected by pronounced shading
around one side of the capillary.
SubCapillary inspection can easily
measure features of
complex shaped
capillaries. Leg length
and width or lobe
radius can be
automatically
inspected. Yarn
characteristics are
directly related to this
geometry.
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Edge wear, characterized by uneven rounded edges, can also be automatically detected.
![]() Edge Wear |
![]() Edge Fractures |
By inspecting the capillary first with back light, then with front light, the worn edge (seen in the black ring above) can be measured. This allows an objective determination of wear to be made.
By inspecting the beginning of the capillary in the counterbore, and then the exit at the spinnerette surface, the length of the capillary can be measured. Capillary length uniformity can then be found.
All SpinTrak models are fully automatic and come complete with a spinnerette platform, a motorized microscope magnification system, and Windows NT based system controller running SpinTrak software.
To start, spinnerettes are loaded onto the inspection platform, the serial numbers are entered, and automatic inspection begins. Using its advanced machine vision technology, the SpinTrak inspects 100% of the capillaries on each spinnerette, magnifying and independently calculating measurements for each capillary.
Based on such criteria such as the tolerance base for each measurement, the number of allowable failed capillaries per spinnerette, and the number of allowable plugged capillaries, each spinnerette can simply be qualified as either “Passed” or “Failed.” In addition, SpinTrak provides graphs and pictorials of capillary data, helping to identify cleaning and extrusion problems.
Before each inspection run, the SpinTrak automatically calibrates the optical measurement system, assuring high accuracy and repeatability. Also, when new spinnerette types are added to the production process, SpinTrak automatically learns the capillary locations by scanning the surface at low magnification.
These and other essential features, in a userfriendly software environment, allow fiber producers total control over spinnerette inspection.