Research On Microinjection Moulding Based On Microfluidic Chip

The process of microinjection moulding is still developing, while it is already mature in traditional moulding. Many problems are unsolved.In this research, a mould of microfluidic chip is designed and fabricated. The injection moulding for this microfluidic chip is simulated by Moldflow and a series of experiments is carried out to find out the practicable range of each process parameter. After adjusting the thickness of the cavity to improve the process, an experimental scheme that focuses on the effect of melt temperature and injection speed upon product quality is made.The results show that the higher the melt temperature is, the better the qualities of the micro channels are, but this effect turns weak gradually as the temperature rises. It is also observed that the sink marks increase gradually on the product surface as the melt temperature rises, namely, the better the qualities of the micro channels are, the worse the qualities of the surfaces are.The causes of defects are analyzed by Moldflow. At the fill stage, the melt can hardly flow into the corner of the micro-channel-core because the dimension of the product is much larger than the micro channel on it; at the packing stage, on the one hand, the frozen layer on the micro channel surface thickens rapidly, on the other hand, the press in the melt distributes nonuniformly and falls as the product solidifies, both weaken the effect of packing. The factors above finally cause the defects of the micro channels. In this paper, the causes of the surface defects are also discussed.This paper can be used for reference in developing the process of injection moulding for microfluidic chip, researching on influencing factors in the microinjection moulding and analyzing the causes of product defects.