Effects of refining parameters on fibre quality measured by fibre cube

Fibre quality and fibre size distribution are important parameters for MDF production control. Sophisticated and automated systems are not available on the market so far, in order to meet the requirements for a sufficient testing device . In this paper a newly developed system is presented: FibreCube. This device enables the measurement of fibres, esp. for fibreboard production, with a suitable resolution, testing speed, and data evaluation. With this method it is possible to analyse the effect of process parameters (i.e. wood species, refiner disc gap) on the fibre size characteristics. In this paper it is shown that the effect of wood species and process parameters on the fibre quality can be clearly differentiated: Pine wood fibres show a quite even distribution of fibre length with a mean slightly lower than 3 mm. The proportion of short fibres is relatively small. Beech wood fibres show a much higher content of short fibres with a mean at about l mm. With an increased refiner disc gap the distributions changes clearly; the mean is shifted to a higher fibre length, the amount of shorter fibre decreases, and the number of longer fibres (i.e. shives) increases. Finally, the content of fine fibres is higher for moulding grade MDF than MDF than HDF. Simultaneously, the content of larger fibres is higher for HDF than MDF than moulding grade MDF. These findings indicate the potential of an adequate measuring system for MDF industrial production, which facilitates the detection of changes in the defibration process, as a consequence of changes in fibre quality, and predicts changes in panel properties before pressing. In summary, fibre characterization is an advantageous tool for process control.