An Experimental Study of the Needled Nonwoven Process

Abstract

This series of papers reports three experimental methods that have been used in a recent study of the wool needle-punched nonwoven process. Although the measurement results are specific to wool fibers, the experimental techniques can be applied generally to study the needle-punching process. The first paper presents a method of quantifying the two-dimen sional geometric characteristics of wool fibers in the card web for feeding to the needle- punching machine. The overall characteristics of the fiber curve are important to the fiber geometry change during the transformation of a card web to a consolidated nonwoven fabric. We use a minimum-width rectangle technique to characterize the overall fiber shape in the card web. Fiber characteristics, such as extent, shape factor, orientation, and area density of the fibers, are measured from the minimum-width rectangle. The fiber geometry is further classified into hooks (trailing and leading), straight fibers, U-bends, and loops and entangle ments. The fiber geometric features are analyzed statistically based on over 400 fibers. Hook fibers account for 56% of the card web, straight fibers for 21%, U-bends for 15%, and loops and entanglements for the remaining 8%. Longer fibers are more likely to form hooks, while shorter fibers are more likely to form U-bends and straight fibers.