How planing affects warp

Abstract: Although planers and wood machining researchers have been around a long time, the interactions between planks and planers have been neglected in basic research. With a solid understanding of the movements of planks during planing, planers and planing strategies can be developed to reduce waste and improve the value yield.Cutting depths, changes in the amount of warp and cross-sectional shape were used to analyse the movements of the planks during planing, the alignment between the planks cross-sections and planers cutters and the improvement potential. The feeding roller in the planer intake had most control over the plank motion. Apart from cup reduction, the parts mostly affected by planing were the top and the butt end, where twist-induced misalignment between the cross-sections and the planers cutters resulted in skewed cross-sections and reduced rectangularity. By adjusting the cutting depths and in some cases the sawing oversize, planer misses could have been avoided but improvements in rectangularity would have required changes in the planer setting or planer design.This thesis increases the knowledge on how a 4-side planer works together with warp to affect 50 × 150 mm planks. For the 20 planks used in this study, the planer removed cup, it decreased the amount of twist and crook but had no effect on bow. The major factor reducing the rectangularity of the planed planks was twist. In the future, knowledge derived from this thesis can be used to create a simulation tool to model the behaviour of warped planks in a planer.