Milling of wood and wood-based materials with a computerized numerically controlled router I. On the machining accuracy for grooving

The objective of this study was to obtain basic information for programming the most accurate milling of wood and wood-based materials with a CNC (Com puterized Numerically Controlled) router. In this paper, the machining accu racy for grooving MDF, particleboard, plywood and katsura (Cercidiphyllium japonicum Sieb. et Zucc.) with a CNC router under various milling condition s was studied. Especially the effects of spindle speed and feed per knife o n groove width were examined. The results obtained are summarized as follows: 1) During idling at the spindle speed of 333 rps vibration was large becaus e of resonance of the spindle head of the CNC router. 2) Uncut remains were recognized in the down-milling surface in plywood, an d they became larger with increasing feed per knife. 3) Cutting error for both MDF and particleboard was almost unaffected by sp indle speed or feed per knife. 4) All cutting errors for plywood had negative values. In the cases of feed per knife of 0.2 and 0. 3 mm, they became larger with increasing spindle s peed. 5) In the case of 0 degrees grain angle in katsura, the cutting error was a lmost unaffected by feed per knife and varied slightly from negative to pos itive values with increasing spindle speed. 6) In the cases of 45 degrees and 90 degrees grain angle, all cutting error s had negative values. 7) In the case of 135 degrees grain angle, the cutting error varied from po sitive to negative values depending on the combination of spindle speed and feed per knife.