Micromilling of Poly(methyl methacrylate, PMMA) Using Single-Crystal Diamond Tools

This paper presents an experimental investigation on micromachinability characteristics of Poly(methyl methacrylate) (PMMA, with the common trade names of Acrylic® or Plexiglass®) when using single-crystal diamond micro-endmills towards enabling rapid, accurate, and reproducible fabrication of PMMA parts for a broad range of applications. An experimental study with a full factorial design is conducted using a straight single-crystal diamond micro-endmill with a diameter of 450 μm. A set of full-immersion micromilling tests are performed within a custom-made miniature machine tool under varying spindle rotational speeds (90, 120, and 150 krpm), feed rates (5, 10, and 15 μm/flute), and axial depths of cut (50 and 100 μm). The effects of cutting conditions on process forces, surface roughness, burr formation, and shape retention (of the fabricated channels) are analyzed. It is shown that micromilling using single-crystal diamond micro-endmills reduces surface roughness, burr formation, and force magnitudes, while creating high-quality features as compared to those obtained when using commercially available tungsten carbide micro-endmills. Favorable cutting conditions and machining strategies for effective creation of micro-scale features on PMMA can be identified using the presented micromachinability study.