Thesis Details


Thesis Title: The effects of barb depth, barb angle, and blade shape on the operative life of needles and the physical properties of needlepunched fabric
Thesis Author: Gregory Webb
Abstract: 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.