Machining of wood using a Rip Tooth: effects of work-piece variations on cutting mechanics

Genetics and environmental conditions during the growth of wood are known to affect the intrinsic characteristics influencing cutting mechanics. To evaluate this, a full factorial experiment has been performed investigating the effects of three significant factors involved in wood machining; wood species, moisture content and grain direction. A variety of woods were evaluated (five softwood and three hardwood species) at four moisture levels. As all woods are heterogeneous, anisotropic materials, machining was performed parallel and perpendicular to the grain direction. A three axis CNC router was used to drive a tool resembling a rip tooth, at low velocity, through each of the sixty-four wooden work-piece variations at three different depths of cut. To collect quantitative data, a piezoelectric dynamometer was used with a data acquisition system to measure and record the cutting and thrust force components acting on the tool. Chip formation and work-piece deformation was observed using images taken from an optical microscope. In this paper the results from the rip tooth experiment are compared to published results [1-7] in for planing operations from fundamental literature.