The Machinability of Flat-Pressed, Single-Layer Wood-Plastic Particleboards while Drilling—Experimental Study of the Impact of the Type of Plastic Used

Abstract

Machinability testing of ordinary wood-based panels can be useful, but testing prototypical (not produced industrially) panels is even more useful. So, the innovative (made only on a laboratory scale) flat-pressed WPCs were the subject of this study. The study consisted of experimental machinability testing of samples of fourteen different types of particleboards. Nine of them were innovative (non-commercial by design) particleboards, which differed from each other in terms of the type of plastic that was used and its percentage. The wood particles were bonded with either polyethylene (PE), polystyrene (PS) or polypropylene (PP). The percentages of plastic were either 30%, 50% or 70%. The research stand used for testing the machinability while drilling was based on a standard CNC (computerized numerical control) machining center. The experimental procedure involved the use of a specialized, accurate system for measuring cutting forces. Moreover, the maximum widths of the damage zones visible around the hole, on the drill entry side and the drill exit side were monitored using a digital camera and graphical software. Two key relative machinability indices were determined (quality problem index and cutting force problem index). Generally, the machinability of wood–polypropylene (W-PP) and wood–polystyrene (W-PS) composites was relatively good and generally similar both to each other and to the machinability of raw, standard particleboard P4. However, wood–polyethylene (W-PE) composite turned out to be the best wood-based board that was tested (even better than standard MDF) from the point of view of the cutting force criterion. On the other hand, the general quality of the holes made in W-PE composite was very poor (not much better than for raw, standard particleboard P5, but clearly better than for standard OSB).