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Abstract:
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The relationship between wear of the needle and resultant fabric properties in a
needled fabric is a concern of the needlepunch industry. Currently, needlepunch felt
manufacturers may be purchasing needles that give them desired fabric properties, but wear
of the needle may give undesirable fabric properties prematurely. This thesis research
investigated needle designs to determine the effect of design upon the needle's operative life
and the physical properties of needlepunched fabric. Besides the obvious savings in needle
replacement cost, a longer needle operative life will lessen the amount of lost productivity by
decreasing the amount of needle changes and the amount of machine downtime associated
with needle changes.
To determine the effects of barb angle, barb depth, blade shape, and wear on needle
efficiency and fabric physical properties (strength, elongation, air permeability, and
thickness), ten needle designs were evaluated at five different stages of wear. Web
formation and needlepunch loom settings were held constant for all fifty fabric samples. A
fiberglass mat was used as the web to accelerate wear of the needle.
Needles from each condition were tested for needle efficiency. Needles from each
condition was photographed for subjective view. Each fabric sample was tested and values
for strength, elongation, air permeability, and thickness were recorded. Results were
analyzed and the effects of independent variables and their interactions were determined.
The following general results were found:
1. A barb depth of 0.003 inch increased fabric thickness, decreased air
permeability, produced stronger, less elastic fabrics, and was less efficient
compared to a 0.004 inch barb depth.
2. A 5° barb angle created weaker, more elastic fabrics. The angle also
increased fabric thickness and air permeability. The 20° barb angle was more
efficient.
3. A triangular blade shape formed loftier, more permeable fabrics than a
pinch or star blade design. The pinch blade was the most efficient blade
design.
4. Unworn needles produced denser, less permeable fabrics
and were more efficient than worn needles.
5. Significant interactions were:
a. Fabric Thickness
1. Pinch blade with a 0.003 inch barb depth formed thicker
fabrics than a pinch blade with a 0.004 inch barb depth.
2. Unworn star blade needles with a 20° barb angle created
denser felts than worn star blade needles with a 20° barb angle.
b. Air Permeability
1. Felts needled with worn needles and 20° barb angles were
less permeable than felts made with unworn needles and 20°
barb angles.
2. Pinch blade needles with a 5° barb angle and a 0.004 inch
barb depth formed more permeable fabrics than pinch blade
needles with a 5° barb angle and a 0.003 inch barb depth.
3. The least permeable felts were needled with a star blade
needle, a 0.003 inch barb depth, and a 20° barb angle.
c. Fabric Strength
1. The strongest fabric was needled with the needle design: a
star blade, a 0.003 inch barb depth, and a 20° barb angle.
Using a 5° barb angle, the pinch blade with a barb depth of 0.003 inch formed the strongest fabrics. However, increasing
the barb depth to 0.004 inch significantly reduced fabric strength
in both aforementioned conditions. The reduction in strength
was so drastic with a pinch blade that the weakest felts were
produced with the pinch blade, 0.004 inch barb depth, and 5°
barb angle needle design.
2. Unworn star blade needles created stronger felts than worn
star blade needles.
d. Elongation
1. A 5° barb angle combined with a 0.004 inch barb depth
produced a more elastic fabric; and a pinch blade with a 5° barb
angle and a 0.004 inch barb depth created the most elastic felt.
2. Using new needles with a 0.003 inch barb depth, a
triangular blade formed the most elastic fabrics. A star blade
with a 0.003 inch barb depth created the least elastic fabrics
when needling with a 20° barb angle.
3. Needling with a 0.004 inch barb depth, an unworn star blade
created a lower elastic fabric.
6. The coefficient of friction was higher for fiberglass than polyester, yet, the
fibers wore the needles similar.
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