High-precision optics by application-optimized compression induced solidification (CIS)

由聚合物技术研究所开发的压缩诱导凝固（CIS）加工技术有助于消除标准塑料加工过程中出现的下沉痕迹、残余应力和翘曲等问题，这些问题是聚合物熔体经历两阶段冷却时产生的。CIS工艺是可能的，因为非晶塑料的玻璃化转变温度范围与压力有关，并随着压力的增加而向更高的温度转变。因此，无论厚度如何，塑料可以首先在腔内施加压力，在更高的温度下固化，然后冷却为固体。DFG资助的项目“Grundlegende Betrachtungen zum Einfluss hoher drcke auf den phasen<e:1> bergang bei der Kunststoffverarbeitung”和“Übertragung der Grundlagen auf die Spritzgießvariante druckverfesung”阐述了对非晶态热塑性材料的基本理解，并通过生产精确和均匀的零件显示了CIS背后的巨大潜力。随着实验模具的制造，CIS能够集成到自动化注射成型过程中。然而，尽管取得了这些进展，但目前的周期时间太长，无法在当前状态下将CIS用于工业目的。此外，试验模具背后的模具技术对于进一步的工业应用来说仍然过于复杂和昂贵。因此，转移项目“应用优化的高精度光学，压缩诱导凝固”的目的是通过创新方法减少CIS周期时间。此外，模具和过程控制概念将得到改进和简化，以进一步促进CIS在现有加工框架中的实施。为了缩短CIS循环时间，产生了许多值得科学研究的问题。首先，压缩速度对构件体积和物理老化的影响描述不够充分。这对于在较高温度下使用的组件尤其重要。另一个重要的问题是，在压缩过程中，不同的熔体温度对腔内构件性能的影响。这种效应与聚合物熔体的压力依赖粘度直接相关，这需要用新型科学设备“gegendruckvisksimeter”进行分析。此外，由于由工艺本身决定的高腔压力，对于厚壁部件的微结构的精确印象也非常有希望。随着标本“圆盘”的制作，上述几点可以进行科学和经验的研究。一个组件“透镜”实际证明了经济生产高精度塑料光学与创新的CIS方法的能力。

The processing technique Compression Induced Solidification (CIS), which was developed at the Institute of Polymer Technology, facilitates obviating problems with standard plastic processing like sink marks, residual stresses and warpage, which arise while the polymer melt undergoes a two phase cooling. The CIS process is possible because the glass transition temperature range of amorphous plastics is pressure dependent and shifts to higher temperatures with increasing pressure. Thus, the plastic can first be solidified at higher temperatures by applying pressure within the cavity, regardless of thickness, and then cooled as a solid. The DFG funded projects "Grundlegende Betrachtungen zum Einfluss hoher Drücke auf den Phasenübergang bei der Kunststoffverarbeitung" and "Übertragung der Grundlagen auf die Spritzgießvariante Druckverfestigung" have expounded upon the fundamental understanding of amorphous thermoplastic materials and shown the great potential behind CIS by producing precise and homogeneous parts. With the fabrication of experimental mold CIS was able to be integrated into automated injection molding processes. Yet, despite this progress the current cycle time is too long to be able to employ CIS for industrial purposes in its current state. Additionally, the mold technology behind the trial mold remains too complicated and expensive for further industrial applications. The purpose of the transfer project "High precision optics by application-optimized, compression induced solidification" is, therefore, to reduce CIS cycle time with innovative approaches. Additionally, the mold and process control concepts will be improved upon and simplified to further facilitate the implementation of CIS into existing processing frameworks. Numerous points meriting scientific research arise from the aim to reduce CIS cycle time. Firstly, the compression speeds effect on the components volume and physical aging remains insufficiently described. This is particular important for components employed at higher temperatures. Another important point is the varying melt temperatures effect on the component properties in the cavity during compression. This effect is directly related to the pressure dependent viscosity of polymer melts, which is to be analyzed with the novel scientific equipment 'Gegendruckviskosimeter'. Furthermore, the exact impression of microstructures is also very promising for thick walled components, because of the high cavity pressures as determined by the process itself. With the production of a specimen 'disc' the aforementioned points can be scientifically and empirically researched. A component 'lens' practically demonstrates the capability of economically producing high precision plastic optics with the innovative method of CIS.