Industrial evaluation of drying stresses in oakwood dimension parts

This paper deals with an overview of the advantages and disadvantages of laboratory and industrial methods for the evaluation of drying stresses determination and quantification after the drying process, using an example of a casehardening evaluation on samples of two equal oakwood dimension parts (27 mm thick) drying processes in a conventional kiln dryer. The method used was one of the two known methods (TRADA (1985)) of the casehardening determination tests, where deformation has been observed on a special diagram dividing casehardening into four different gronps. As expected the testing results were better (research was performed on the dimension parts instead on boards) than when the sampling was done according to the terms (minimal distance from the end of the board). In the first drying process 73 % of the samples had low casehardening, 20 % moderate and 8% were without stresses. In the second drying process 43 % of the samples had low casehardening, 26 % moderate, 8 % severe and 23 % were without stresses. Using the results it can be concluded that the samples taken from those processes can be evaluated as moderately stressed. The method used in this work can be used for a general evaluation of a drying process quality in an industrial environment, not having any precise casehardening quantification. The results and testing method will be applied as a direction for use in the woodworking companies in Croatia, but further research has to be done using the other mentioned industrial and laboratory methods for the evaluation of drying stresses.