Lathe Checks Formation, Measurement and Effect on Plywood Quality - European Hardwoods

Lathe check formation and measurement have received a lot of attention in the past. Reliable results about the lathe checks properties have been obtained mainly by using microscopy techniques, measuring the check depth and the frequency. However, microscopic measurements are time-consuming and laborious. Moreover, only a limited amount of specimens could be evaluated during the study, which often leads to high dispersion of obtained results. In order to automatize the lathe check depth and frequency measurement several methods have been introduced, e.g. ultrasound, acoustic, however these methods do not give high quality information about the check properties. During the present study, the SMOF was used in order to measure high quantity of samples and evaluate the effect of processing parameters on check formation and properties. This method will enable to evaluate remarkable amount of checks immediately after the peeling process, from the wet veneer at microscopic level. In this study the effect of peeling temperature and compression ratio on lathe checks properties were evaluated from European hardwoods. The results of the study show that at higher temperature, shallower and more frequent checks are formed compared to lower temperature. Moreover, higher compression ratio produced veneer with shallower and more frequent lathe checks. The results also reveal that the rays could affect the propagation direction of lathe check in veneer, hence the anatomical structure plays remarkable role in check formation