Abstract:

In micro injection molding，due to scale effect，convective heat transfer behavior between the polymer melt and the wall of micro mold cavity is different from that of conventional injection molding，and convective heat transfer coefficient changes obviously. By using a test device consisting of micro-injection machine，temperature transducer and micro mold，the mold temperature distribution of PP，POM and ABS melt filling the micro-cavity with different injection rates，cavity thickness of 0.510 mm，0.420 mm and 0.325 mm，surface roughness of Ra0.062 μm，0.393 μm and 0.695 Ra0.062、0.393、0.695 μm微型腔时的模具温度分布进行测量，获得了模具的热通量，进而求得熔体与型腔壁面间的对流传热系数。结果表明，微尺度下实验聚合物熔体与型腔壁面间的对流传热系数，均随注射速度和型腔表面粗糙度值的增加以及型腔厚度尺寸的减小而明显增大；但聚合物材料性能不同时，其对流传热系数差别也较大。