P_2.1.5 pregrading

At the moment, the grading of sawn timber is carried out once the drying process is completed and is done either visually or with the help of machines. The current sets of rules and standards lays down the grading process such that the grading class remains unchanged as long as any dimensional reduction does not fall below a certain size, in which case a renewed grading has to take place. Frequently the rule with timber-processing enterprises is to buy ungraded sawn timber, dry it and only subject it to grading immediately before production. In this way, i.e. not knowing the quality, often a high percentage of sawn timber accrues which cannot be processed any further although it was originally intended for production. Sawn timber which can not be further processed as intended needs to be used in a different way, and since this is often not possible at the same company requires further transport and therefore more transport costs. In contrast to this situation, an optimised pre-grading based on the fresh state of the timber could ease the situation; here, a grading process according to quality would take place in the early stages of the production chain. It has been found out that already the round timber or freshly cut sawn timber allows for a grading using various methods; of these viable methods, the measuring of the eigenfrequency seems by far the most suited.

It is the objective of this project to further develop and optimise the pre-grrading process while taking into account the relevant moisture content of the timber (wet and frozen). In order to do so, an analysis is carried out as to which point in time is best for grading, of the entire timber procurement and production chain. Additionally, based on the findings so far obtained, the quality categorisation of the freshly sawn timber shall be made more precise up to the point that the optimum saw timber can be located as early as that. Through a serial arrangement of various sorting methods it is being examined whether and in how far a grading of wet timber can actually replace a grading of the dried timber. Depending on the envisaged further production, the procedure to be developed can be adapted and optimised. Therefore, it can be stated that it must be the next important objective to implement such a newly developed grading device in industrial operation. Here, there is a connection to the projects “Development of an Automated Sorting Plant Based on Specific Firmness Parameters by means of Tensile Proof Loading Procedure” (2.1.3 APTM)“ as well as " Utilization of the Mechanical Potential of Large Dimensioned Timber for System Structures in Engineering Timber Constructions" (2.1.1 APTM)“.