NONDESTRUCTIVE QUALITY ASSESSMENT OF ASH TIMBER TOOL HANDLES WITH DYNAMIC IMPACT LOAD

The production of tool handles is one of the most important industrial utilization of ash timber of small dimensions. Because of an optimal normalization of the produced handles and in order to optimize their q uality assessment, the timber handle industry is already interested in developing accurate and cost-effective quality control systems for th e application in their production lines.The main subject of this proje ct was the analysis of a non-destructive method for the evaluation of the quality of tool handles from industrial production, especially of handles with dynamic impact load (hammer and axe handles). For this pu r pose, the statistical relationships between relevant mechanical prop erties (impact bending load) and non-destructive parameters (vibration frequency, density and ring width) were analysed under respect of wit h different ring orientations. For non-destructive evaluation of stren gth properties GRINDOSONIG was used. The results show that the applied measuring instrument allows a very fast and easy determination of the vibration frequency of the non-prismatic timber handles. The combined consideration of the vibration frequency and of the density in a mult iple regression model shows an acceptable level of determination of th e strength properties (around 60%). That could allow a sufficient accu rate quality classification of the products in the industry, either as complement or as complete substitution of the normally used visual cl assification. Additionally, an accurate prediction of the final handle properties on the prismatic beams, from which the handles will be sha ped, could be demonstrated, in order to minimize the production costs. The exact determination of a quantitative parameter (combination of v ibration frequency and density) instead of the subjective visual class ification increases the possibilities of application of a cost-effecti ve ''machine-control-system'': all produced handles could be evaluated , more quality classes could be identified and the obtained quantitati ve value could be used for a certificate of quality control.