Photoelectric Twist Irregularity Tester

The reflected light from a yarn squeezed flat shows its peak value when measured in a plane vertical to the twisted fibers. A twist irregularity tester based on this principle, which operates automatically and records the change of twist angle, was constructed. Several twist irregularity curves were obtained with both staple yarns and continuous filament yarns. Some factors affecting the accuracy of the test results were discussed, and the curve was compared with the twist angle measured by visual observation.