Chipper-canter infeed technology has changed greatly over recent years. The self-centering mechanical devices installed in the 1970-1990 period have been replaced with more sophisticated systems that also control log alignment and translation. These optimized systems allow for improved yield, but they are also more complex and require more attention and maintenance. The purpose of this study was to compare four different infeed systems illustrating infeed technology evolution over time, as applied to small logs, where optimization and positioning errors are more critical.
Theoretical simulations of the four infeed types studied showed that a system optimized for both alignment and translation can produce 9% greater revenue than self-centering straps, as compared with 8% for a translation-only optimized system, and 5% for self-centering rollers.
In mill tests, a system optimized for alignment and translation yielded 8% greater revenue than the basic self-centering straps, as compared to 6% for the translation-optimized system, and 5% for the self-centering roller device. Actual efficiency ranged from 91 to 93% independently of technology level, as it was determined by mechanical damage, sawing variation and rotation errors.
According to our evaluation of mechanical damage to lumber in the canters, losses averaged $11/Mbf, but the results varied significantly, ranging from $3 to $16/Mbf. Defects were mostly related to cutting parameters and knife maintenance, rather than the technology level of the equipment. Of the four types of equipment in the study, three would have benefited from a pre-cutting saw to minimize damage, as the loss of chips associated with sawkerfs amounted to $6/Mbf.
Rotation errors had less impact on optimized infeeds than on mechanical self-centering devices thanks to a second – post-rotation – optimization. Our simulations showed that rotation errors could reduce efficiency by 7% in the case of self-centering straps, 4% with self-centering rollers, but only 1% with optimized systems of both types.