Wöhner Timo, Islam Aminul, Hansen Hans N, Tosello Guido, Whiteside Ben R
Department of Mechanical Engineering, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.
The Centre for Polymer Micro and Nano Technology (Polymer MNT), University of Bradford, BD7 1DP Bradford, UK.
Micromachines (Basel). 2020 Apr 17;11(4):424. doi: 10.3390/mi11040424.
The formation of blister in the injection moulded parts, especially in the film insert moulded parts, is one of most significant causes of part rejection due to cosmetic requirements or functionality issues. The mechanism and physics of blister formation for molded parts are not well-understood by the state-of-the-art literature. The current paper increases the fundamental understanding of the causes for blister formation. In the experiment, a membrane strip of 5 mm in width was overmoulded with Polypropylene (PP), which formed a disc-shaped part with a diameter of 17.25 mm and a thickness of 500 µm. To investigate the influence of the processing parameters, a full factorial design of experiments (DoE) setup was conducted, including mould temperature (T), barrel temperature (T), injection speed (V) and packing pressure (P) as variables. The degree of blistering at the surface was characterized by the areal surface roughness parameters Spk and Smr1, measured with a confocal laser microscope. The measurements were taken on the 10 mm long section of the membrane surface in the centre of the moulded part across the entire width of the film. In addition, the film insert moulding (FIM)-process was simulated and the average shrinkage of the substrate material under the membrane was investigated. Eventually, a method and processing window could be defined that could produce blister-free parts.
注塑成型部件中气泡的形成，尤其是薄膜嵌件成型部件中的气泡形成，是由于外观要求或功能问题导致部件拒收的最重要原因之一。目前的文献对成型部件中气泡形成的机理和物理过程了解并不充分。本文增进了对气泡形成原因的基本认识。在实验中，用聚丙烯（PP）对宽度为5毫米的膜条进行二次注塑成型，形成了直径为17.25毫米、厚度为500微米的圆盘形部件。为了研究加工参数的影响，进行了全因子实验设计（DoE）设置，将模具温度（T）、料筒温度（T）、注射速度（V）和保压压力（P）作为变量。表面气泡程度通过用共聚焦激光显微镜测量的表面粗糙度参数Spk和Smr1来表征。测量是在成型部件中心的膜表面10毫米长的区域内，横跨薄膜的整个宽度进行的。此外，对薄膜嵌件成型（FIM）工艺进行了模拟，并研究了膜下基材的平均收缩率。最终，可以定义一种能够生产无气泡部件的方法和加工窗口。
