edge machinability of mdf : effect on surface quality and

EDGE MACHINABILITY OF MDF : EFFECT ON SURFACE QUALITY AND CONSEQUENCES FOR GLUING P. Triboulot *, A. Zerizer *, C. Sales **, P. Martin * * ESSTIB - University of Nancy I - BP 239 - 54506 Vandoeuvre Cedex ** C.T.B.A. - 10 avenue de Saint Mandé - 75012 Paris MDF is becoming the basic wood based material used in the furniture industry. Due to its manufacturing process it presents an heterogeneity of density according to its thickness. So, the quality of machined edges is better near faces than inside. For many end products, the edges must be moulded to give an appropriate shape before gluing the surface coating (wood and synthetic veneers, solid wood, ...) Then, the main goal of the research is the improvement of machining process to produce edge surfaces with the required quality for a high gluing toughness. The fracture energy ratio ( G1c )is measured using cantilever beams samples and the results are analysed to qualify the toughness of two planned MDF pannel edges glued together. The industrial manufacturing performances to obtain the required G1c (cutting power, tool wear) are taking into account as well as the chip shape and its relevent consequences on wood sawdust outlet and to reduce, by this way, health risks for workers. The monitoring factors of machining are chip thickness, tool design (rake angle), cutting material (HSS and tungsten carbide) cutting mode, and MDF moisture content due to storage conditions. The chip thickness effect on G1c is clearly demonstrated by the experiments. More, it is possible to find a linear relationship between G1c and surface roughness criterion (Ra). The allowed chip thickness is limited by the industrial milling conditions. We can conclude that the chip thickness on the range O.20 up to 0.35 mm is the most significant parameter for a high performance gluing. Pratical cutting conditions can be deduced directly (cutting speed and feedrate).