Towards strand production in primary log breakdown: Effects of the counter-knife and temperature on size distribution of Jack pine strands

Abstract

Effects of counter-knife and wood temperature were studied relative to the size distribution of Jack pine strands processed by a strander-canter. Studied factors included the counter-knife angle (60°, 75°, 90°, and 105°) and the distance between the edges of the counter-knife and knife (6 mm, 11 mm, and 16 mm). The nominal cutting speed was fixed at 25 m/s. Rotation and feed speeds were adjusted to obtain a target strand length of 102 mm, while the target strand thickness was 0.9 mm. The stranding process was performed under two log temperatures, i.e., -13.4 °C (frozen condition) and 18.6 °C (unfrozen condition). Results showed that the proportion of strands, fines, pin chips, and strands’ width were affected by the counter-knife angle and wood temperature. The proportion of strands and the mean strand width increased as the counter-knife angle decreased, while conversely, the proportion of fines and pin chips decreased. Frozen logs produced narrower strands and more fines and pin chips than unfrozen logs. The highest strand proportion, lowest fines and pin chips proportions, and wider strands were obtained with a counter-knife angle of 60° for frozen wood and 75° for unfrozen wood.