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Quality control for machine strength graded timber

Kovryga, A., Stapel, P., van de Kuilen, J. W. G.
European journal of wood and wood products 2017 v.75 no.2 pp. 233-247
quality control, strength (mechanics), wood products, wood quality
The quality assurance of timber properties is important for the safety of timber structures. In the current study, the quality control options of timber are analysed for changing material quality under the prism of the different growth regions. Therefore, the control options—machine and output control in accordance with EN 14081—are simulated, and the performance is assessed and compared using 279,235 timber pieces from a production facility. For the data with only grading information available, the real properties were simulated based on 4158 specimens, for which destructive test results are also available. The results indicate that timber with desired material property values can be produced by both machine and output control. In direct comparison to machine control, the output control delivers timber which matches the requirements more frequently as quality shifts can be detected. Whenever lower timber quality is identified, the settings are increased. The output control system for multiple growth regions is not sensitive enough when the current attribute chart given in EN 14081-3 is used. With higher sampling rate the sensitivity can be increased. With the tested option—yield optimization—no additional yield improvement compared to machine control could be achieved.