1:30 pm – 6:00 pm:
W16-Injection Molding: Processing-Quality Control and Analysis
(Moderators: Adam Kramshuster and Tom Turng)-Room S320H
1:30 pm – 2:00 pm:
Automatic Anomaly Detection and Root Cause Analysis for Holistic Process Monitoring and Control in Injection Molding
Alexander Schulze Struchtrup, University of Duisburg-Essen
Modern injection molding machines with state-of-the-art control technology enable plastics-processing companies to operate processes resulting in high part quality and low reject rates. However, external influences such as fluctuations in the material properties may cause the production of bad parts, which is often detected with a time delay, causing high costs. Based on this, the present paper describes a procedure to gain valuable information from the continuously generated process data. It shows how methods for anomaly detection and localization of their underlying root causes can help machine operators identify critical process states more quickly. This in turn leads to lower reject rates and machine down times and thus an enhanced overall process control.
2:00 pm – 2:30 pm:
Inflation Behavior of Preforms in the Special Injection Molding Process GITBlow Combining Gas Assisted Injection Molding and Blow Molding
Björn Landgräber, Paderborn University
The demand for innovation within the plastics industry has led to a large variety of specially adapted production processes. Meeting the requirements for lightweight and complex shaped part geometries the special injection molding process GITBlow was invented by the Kunststofftechnik Paderborn a few years ago. The process consists of the production of a preform via gas-assisted injection molding (GAIM) and a secondary gas injection for a further inflation of this preform within a larger cavity. In this paper the focus is set on the second gas injection and the inflation behavior of the preform. Despite the similarities between this step and conventional injection blow molding, there are some distinctive differences concerning the temperature level and temperature distribution prior to the inflation. In a systematic approach with several materials and process settings, a process characteristic strain rate profile is determined using a specially adapted mold. Using the laws of fluid dynamics, the measured profiles are analyzed in more detail.
2:30 pm – 3:00 pm:
Effect of Injection Molding Condition on Mold Adhesion During Thermoplastic Polyurethane Injection Molding
Jian-Yu Chen, Feng Chia University
Injection molding is one of popular approach for the mass-production of plastic products with complex geometries. Although it is convenient and cost-effective to manufacture goods, some issues such as warpage, quality fluctuation of injection molded part, surface defects, insufficient physical properties are still needed to overcome. During ejection stage, one of annoying issues called mold adhesion, which happens to the interface between molded part and cavity surface, makes molded part difficult to release from mold surface, and the defects such as distortion and crack also occur as serious mold adhesion effect arises. This phenomenon is familiar during thermoplastic polyurethane (TPU) injection molding process. There are numerous factors affected the mold adhesion level, including injection molding conditions, surface morphology, surface modification, rheological properties of molten polymer. In order to understand the effect of molding conditions on mold adhesion level, tensile mode mold adhesion tester was proceeded to quantitatively evaluate mold adhesion level. In addition, surface free energy measured on molded part surfaces was carried out to better understand the wettability. In experiment results, mold temperature and melt temperature both effect on mold adhesion level. Moreover, the responses of SFE on different mold adhesion level are apparent.
3:00 pm – 3:30 pm:
Stabilization of BMC Injection Molding by Process Control Measures
Nicolina Topic, KraussMaffei Technologies GmbH
Polyester molding compounds form a quarter of Europe´s glass fiber reinforced plastics production. Their main applications are automotive parts such as exterior body parts and headlight reflectors. Dependent on the processing method there are two types of polyester molding compounds which mainly differ in their composition and raw material condition. For compression molding sheet molding compounds (SMC) are used, while bulk molding compounds (BMC) are processed by injection molding. In comparison to SMC compression molding, BMC injection molding allows higher production rates at a better process reproducibility. However, there are several effects such as material induced interferences or changing ambient conditions that cause fluctuations and lead to varying part quality. The manual adaption of the relevant process setting parameters presents an option to react on such interferences and prevent further rejects. The outcome of these adjustments is dependent on the experience of the operator, since an accurate knowledge of the influence of certain setting parameters on individual part quality features is required. In this paper the impact of occurring interferences on the volumetric part filling is analyzed. In order to prevent negative effects by these disturbances, two existing process control measures, which react inline on fluctuations by automatically adjusting relevant process parameters, are used and validated.
3:30 pm – 4:00 pm:
Zero Defect Manufacturing in Injection Compression Molding of Polymer Fresnel Lenses
Dario Loaldi, Technical University of Denmark
Fresnel lenses are polymer optics with reduced dimensions and higher illumination properties. Their structured profile involves high precision replication techniques when industrial scale manufacturing is concerned. Injection Compression Molding (ICM) is the state of the art replication technology to ensure mass production of polymer optics. The opportunity to perform a compression phase on the polymer melt while injected into the cavity, ensures a more homogenous replication of the part, enhancing birefringence and transparency among all the optical properties. However, it is not common to find studies concerning the technological signature of ICM components. The optical transparency of polymer optics as long as the complexity of Fresnel lens profile, are big challenges for metrology making this knowledge expensive and rarely investigated. In this study, absolute dimensions of Fresnel lenses step heights are correlated with respect to ICM process conditions. In a first experimental plan, the effect of packing and compression is individually evaluated on two different materials. In the case compression is performed without packing, the form replication accuracy of the micro structures fails, showing deviations up to 10 times the nominal dimension. On a secondary experimental campaign, packing pressure and compression gap are optimized together to identify the most favorable replication condition. The results show a second order interaction between compression gap and packing pressure. The average replication increases by 1.4 % when both a high level of compression gap and packing pressure are selected.
4:00 pm – 4:30 pm:
3D Surface Characterization of Etched, Injection Molded Parts Before a Follow Up Electroplating Process
Jens P. Siepmann, University of Duisburg-Essen
When technical polymers like acrylonitrile butadiene styrene (ABS) or polycarbonate/ acrylonitrile butadiene styrene blends (PC/ABS) are processed with injection molding machines for a subsequent electroplated coating not only the electroplating parameters, but also the surface of the etched, injection molded part is responsible for the adhesion of the polymer and the metal ,. In this paper, the effects of processing parameters and mold geometry on the surface structure of injection molded ABS and PC/ABS parts after etching within the electroplating process chain are investigated. For this purpose, relevant parameters (injection speed, barrel temperature and mold temperature) are varied in an experimental design. All parts are prepared for the following electroplating by etching the surface with identical parameters (time, temperature). The part surface is measured at different positions on a test part using a confocal microscope, which was identified to offer sufficient resolution to generate micro- and nano-scale depth information of the surface structures. Surface parameters from DIN EN ISO 25178 (height and spatial parameters) are investigated to describe the surface properties depending on the position on the part and the processing parameters. By combining already published methods for the measurement of two-dimensional surface properties using SEM ,  and the new 3D information, findings regarding the properties of ABS and PC/ABS were generated.
4:30 pm – 5:00 pm:
Multilayer Injection Molding of Thick-Walled Optics Using Dynamic Mold Tempering and Optimized Layer Thickness Distribution
Malte Röbig, Institue of Plastics Processing (IKV) in Industry and the Skilled Crafts at RWTH Aachen University
Multilayer injection molding is an established process for an economical production of thick-walled optical components with complex geometric designs. Thereby, plastics optics are built up layer by layer in injection molding. The individual layers require significantly shorter cooling times compared to conventional single-layered optics. In addition, the shrinkage of the individual layers is lower. As a consequence the replication accuracy is increased.
5:00 pm – 5:30 pm:
Using Magneto-archimedes Levitation for Non-invasive Characterization of Injection Molded Parts
Peng Zhao, Associate Professor, Zhejiang University
In a magneto-Archimedes levitation device, a three-dimensional (3D) injection molded part can be levitated with a posture that is closely related to its shape and internal defect. Here, a novel, non-invasive characterization method for 3D injection molded parts via magneto-Archimedes levitation is proposed. FLUENT-EDEM multiphase software was used to simulate the levitation process of the 3D part. Through the results of the EDEM software, the curves of the levitation height, equilibrium posture, and potential energy versus simulation time were obtained. The final levitation height and the equilibrium posture of the part were determined by the principle of minimum potential energy. Several experiments with vari¬ous 3D parts and different internal defects were carried out to verify the proposed method. Experimental results showed that the proposed method had high accuracy in measuring equilibrium posture and levitation height. For defective parts with small voids (2 mm3), the maximum deviation between the calculated tilt angles and the exper¬imental results was less than 4.7°. In general, the proposed method has the potential of broad application in the non-invasive characterization of injection molded parts.
5:30 pm – 6:00 pm:
Verification of Numerical and Practical Approach in Implementing PVT Properties of Polymer to Control to Control Shrinkage Quality of Molded
Tzu-Hsiang Wei, Ph.D Student, Chung Yuan Christian University
Quality optimization is a common concern in injection-molded products. The relation between pressure, specific volume and temperature is a key property in polymer processing. Because of the unpredictability of this relationship, it is difficult to mold products while maintaining quality in volume production. Traditionally, the most common approach to troubleshooting is for an experienced operator to adjust parameters repeatedly. Based on the PVT theory, this study created a practical PVT control technology using an infrared temperature sensor with pressure sensor in the mold. This method was then used to investigate the effect of molding parameters on the controllability and optimization of product quality. Results show that the PVT curves are constant under consecutive molding cycles and reveal the effect of molding parameters on quality controllability. Specific volume is directly related to product properties such as shrinkage, weight, and warpage. Three control methods for optimizing product quality were also investigated. The dynamic PVT control method molds parts with the smallest total shrinkage, heaviest weight, and least warpage. For molding stability, the PVT control method maintains constant product weight, shrinkage, and warpage.