The CNC grinding machine for ultra-precision machining of advanced materials has been developed. The machine can produce flat or curved mirror surfaces of ceramic, silicon and any hard, brittle materials with sub-micron($10^{-7}$~$10^{-8}$) order of surface roughness.
The machine is composed of the high speed hydrostatic precision air spindle, the high damping resin concrete bed, the high resolution AC servo motor, the FANUC 3 axes CNC controller, and the electrolytic in-process dressing apparatus.
Since the bed material for the ultra-precision grinding should have high static stiffness and damping in its property to improve both the static and dynamic performances, the bed was designed and manufactured with epoxy concrete material. The epoxy concrete material was prepared by mixing epoxy resin with different size sands and pebbles.
The modulus, compressive strength, flexural strength, coefficient of thermal expansion, specific heat, thermal conductivity and damping factor of the epoxy concrete were measured by varying the compaction ratio, sizes and contents of the ingredients to assess the effect of the processing parameters on the mechanical properties of the material. Based of the measured properties, the prototype epoxy resin concrete bed for the ultra-precision grinding machine was designed and manufactured.
Then the prototype ultra-precision grinding machine with the epoxy resin concrete bed was designed and manufactured.
Also, the mirror surface grinding of ceramic materials such as $Al_2O_3$-TiC, $Si_3N_4$, SiC and $ZrO_2$ was performed.
From the preliminary grinding experiments, it was found that the grinding machine was satisfactory to produce the mirror surfaces of hard and brittle ceramic materials.
