Abstract: In order to reduce the mass production and manufacturing cost of microfluidic chips and ensure the surface quality and form accuracy of the micro-scale flow channel structures, a superhard cubic boron nitride (CBN) grinding tool is proposed to precisely mill and grind the surface of die steel core to produce the micro convex array structures with controllable form accuracy, and then the polymeric microfluidic chip with micro groove array structures can be efficiently formed by micro injection molding technology. The influences of the milling-grinding process parameters on the surface quality of the micro-structured mold core are analyzed, and the effects of the micro injection molding process parameters on the surface roughness and from accuracy of the micro-structured polymer are investigated and analyzed through the experimental and theoretical mathematical statistics methods. The experimental results show that the more optimal milling-grinding process parameters including the spindle speed, cutting depth and feed rate are 16 000 r/min, 2 μm and 15 mm/min, respectively. Meanwhile, the surface roughness Ra of micro-structured mold core is 0.299 μm. The melt temperature and holding time have great influences on form accuracy PV and bottom surface roughness Ra, followed by holding pressure and injection speed. When the melt temperature, injection speed, holding pressure and holding time are 235℃, 80 mm/s, 5 MPa and 9 s, respectively, the form accuracy of micro-channel reaches 8.950 μm and the surface roughness Ra of micro-channel bottom is 0.055 μm.

Key words: microfluidic chip, milling-grinding machining, micro injection molding, surface roughness, form accuracy