8:00 am – 11:30 am:
M6-Plastics Pipe and Fittings: Testing, Durability and Fracture of Plastic Piping Materials
(Moderator: Dell Doyle)-Room S322


8:00 am – 8:30 am:
Assessment of Polybutylene Plumbing Installations after Long-term Service

Dale Edwards, Engineering Systems Inc.
Several investigations were undertaken involving polybutylene (PB) plumbing systems that had been in service for more than 20 years. A variety of tests were performed on the pipes, including ASTM test that were required for new PB pipe. Various PB pipe samples were submitted for analysis, including pipes from seven different locations around the U.S. The laboratory testing of the PB pipe samples included one or more of the following tests: a visual and microscopic inspection of the samples, dimensional measurements, quick burst testing, oxidation induction time testing, long-term hydrostatic pressure testing, and Fourier Transfer Infrared Spectroscopy (FTIR). The pipes analyzed did not reveal any significant degradation as a result of the long time service in hot and cold-water plumbing systems. This data was consistent with earlier investigations that showed that 18-year-old PB pipe still met the ASTM requirements for new pipe.


8:30 am – 9:00 am:
Performance of Pe Pipe Resins in Chlorine Dioxide Containing Aqueous Solution

Márton Bredács, Polymer Competence Center Leoben
he resistance of polymer pipes in drinking water application against chlorine dioxide (ClO2) is crucial to ensure long-term functionality. The strong oxidative nature of ClO2 can cause an accelerated degradation of polyethylene (PE) resins and eventually shorten mainly the crack initiation time. To study the effect of ClO2 1 mm thick samples from six PE resins were subjected to exposure in 1 and 0.5 ppm ClO2 at 50 and 60 °C. Blank samples were also immersed in distillated water at 60 °C. Advanced material embrittlement with decreased elongation at break was observed in less than 5 weeks of exposure for each PE. Comparing the mechanical properties and the thermal stability various material performance was found. Furthermore unchanged properties of the blank samples point out the immense impact of ClO2 on the degradation of PE grades. The applied fast ranking methodology in terms of ClO2 resistance can serve as a valuable tool for material and stabilizer development.


9:00 am – 9:30 am:
Quantifying Oxidative Degradation in Polyolefin Pipe by IR Spectroscopy

Don Duvall, ESi
Infrared spectroscopy has been used for decades as a means to quantify oxidation of polyolefins. One method used on piping has been determination of a carbonyl index. Another method developed for use on UHMWPE from orthopedic implants is detailed in ASTM F2102. Results of both methods applied to polyethylene pipe will be compared to assess the extent to which results of the two methods can be correlated.


9:30 am – 10:00 am:
Pipe Quick Burst Pressure Investigations of Sample Length on Two Plastics

Bryan Hauger, Hauger Consulting
ASTM D1599 quick burst testing is a test used by plastic pipe manufacturers for various plastic materials. Requirements on the length between end closures relating to pipe nominal outside diameter (OD) are included in the test method. For larger sizes, the minimum length between end closures is 300% of the OD provided this value is not less than 30 inches. Samples require a length between end closures not less than 500% of the OD for pipe of 6 inch nominal OD or less. This presentation contains results on PE piping of 1 inch nominal OD and PVC piping of 12 inch nominal OD at various sample lengths for both materials to determine the effect, if any, of length between end caps on quick burst pressure. To the best of our knowledge, no publication exists in the literature detailing the effects of sample length on burst pressure has important consequences for material qualification and implications for composite piping systems.


10:00 am – 10:30 am:
Innovative Millimeter Waves Technology for Measuring Diameter, Ovality, Wall Thickness and Sagging of Large Plastic Pipes

Katja Giersch, SIKORA AG
Technical innovation at the manufacturing of plastic pipes with diameters from 90 to 3,200 mm and large wall thicknesses lead to impressive progress in product quality and reduction of material costs. Norms precisely define the minimum and maximum permissible diameter and wall thicknesses of a specific pipe dimension and require repeatable processes. To meet these standards and growing demands in the pipe extrusion requires the use of innovative measuring and control systems already in the production process. This paper introduces a new technology based on millimeter waves. It provides a non-contact, non-destructive, online measurement of inner and outer diameter, ovality, wall thicknesses and sagging (sagging of the melt during solidification at a too high viscosity) of large plastic pipes during the extrusion process. The measurement via millimeter waves technology is based on the FMCW (Frequency Modulated Continuous Waves) runtime method. One or two constantly rotating transceivers continuously send and receive frequency modulated millimeter waves thus ensuring the complete recording of the wall thickness over 360 degrees of the entire pipe circumference. From the runtime difference the inner and outer diameter, ovality, wall thickness and sagging is defined. The measuring principle does not require any coupling media and is not influenced by temperature or the plastic material. There is no need for calibration. In the paper we will at first outline the reasons for the development of the system with regards to the demands of the market. We will introduce the new technology as well as the functional principle, technical features and advantages of the millimeter waves technology for the user compared to other available measuring methods. The technology presented leads to repeatable and optimized production processes, increased product quality and cost savings for higher efficiency during pipe extrusion.


10:30 am – 11:00 am:
Effects of Primer on Mechanical Behavior of CPVC Pipe

Bingjun Chen, University of Alberta
This paper compares mechanical properties for CPVC pipe with and without the exposure to primer that is commonly used for surface treatment before the pipe joining, using coupon specimens of different geometries, including round notched pipe ring (NPR) specimens with notch radii from 1 mm to 3.18 mm, flat NPR specimens and ring specimens. All specimens were subjected to the split disc tensile test at a crosshead speed of 1mm/min. The results show a strong influence of the immersion in primer on the mechanical behavior and the level of influence depends on the specimen geometry. Typically, round NPR specimens with the biggest notch radius suffers the most from the immersion in primer. Based on the results, it is believed that the primer weakens CPVC pipe material by reducing its ultimate tensile strength and decreasing the strain required to generate cracking. The study also found that such an influence is more on ductility reduction than on the strength drop, but the influences are interrelated.


11:00 am – 11:30 am:
Fracture Mechanic Principles for Multi-layer Pipe-wall Design

Florian Arbeiter, Montanuniversitaet Leoben
To overcome the competitive nature of stiffness and toughness, multi-layered structures are a potential solution. By using intelligent design criteria, it is possible to severely increase toughness while keeping the stiffness of the structure at a sufficiently high level. This method can be used for smart pipe-wall design in demanding applications. First multi-layer composites of pure and also highly reinforced thermoplastic materials have been produced and tested with regard to their toughness-increase. As expected, interface properties and mechanical property mismatch play a key role in the development of optimized structures.


8:00 am – 11:30 am:
M7-Injection Molding: Injection Mold Technologies
(Moderator: Srikanth Pilla)-Room S320D


 8:00 am – 8:30 am:
Additive Manufacturing of large, temperature-controlled injection molding tools using Arc Welding and Diffusion Bonding

Johannes Ullrich, Hochschule Schmalkalden
The temperature control of molding tools, in this case injection molding, plays a critical role in the quality of manufactured plastic articles. Key parameters such as shrinkage, warpage, crystallinity, etc. can be significantly influenced by the temperature control concept. Variothermal process control in particular delivers good results in terms of flow path length and part quality. For tools in the small to medium size range, these structures can be additively generated by methods such as selective laser sintering. For large workpieces however, such as automobile bumpers or containers, the currently available manufacturing technologies reach the limits of their geometry. Up to now, it has not been possible to additively manufacture such large-format tools while generating temperature control channels at the same time. This paper presents a method of manufacturing large-scale mold tools with temperature control channels by combining the additive manufacturing techniques of arc welding and diffusion bonding with conventional processes.


8:30 am – 9:00 am:
Controlling the Local Part Properties Using a Segmented Temperature Control in Injection Molding

Mauritius Schmitz, Institute of Plastics Processing (IKV) in Industry and the Skilled Crafts
One of the most important challenges in injection molding is to achieve precise parts regarding dimensional stability and warpage. Due to the nature of thermoplastic material properties, the inner properties of a part change drastically with varying conditions like pressure, temperature or shear rate. Additionally, the specific plastics properties may change due to batch variations or ambient conditions like humidity or temperature. This work illustrates a method to influence the part properties locally within the injection molding cycle. This should be achieved by a segmented temperature control in combination with local temperature and pressure measurements. The aim to manipulate the local part properties such that a homogeneous part shrinkage can be achieved, resulting in minimized part warpage. As control variable the local specific volume is used. Therefore, a novel mold was developed to effectively influence the local specific volume using a segmented temperature control. The results have shown, that the part warpage reacts significantly on the changing processing conditions and that the mold is capable of influencing the part properties heavily.


9:00 am – 9:30 am:
Characterization of Filling Performances and Mechanical Properties of Micro Molded Features

Jiang Jing, Zhengzhou University
The achievement of an adequate accuracy of the micro injection molding (μIM) process applied to the replication of micro-features is a complex task. The selection of parameters influences the filling performance as well as the replicated quality of micro-features and local mechanical property. In this paper, the relationship between process parameters, filling morphology of micro-features and mechanical property were investigated based on DOE method. It was found that the biggest contribution of process parameter to replicated quality for micro feature parallel to flow direction was hold pressure, while mold temperature had the most influence on replicated ability for micro feature perpendicular to flow direction. Local mechanical properties were also different between two arrangements of micro features and substrate in the same micro part. The micro feature with high filling height had a smaller modulus than that with low filling height. The modulus on substrate were bigger than that on micro features. Meanwhile, mechanical property on substrate had no relationship with the arrangement of micro features.


9:30 am – 10:00 am:
Valve Gate Open Lag Time in Conventional Hot Runner System

Byungohk Rhee, Ajou University
To optimize the sequence valve gating, dynamic characteristics of valve gate should be considered in CAE simulation and sequence controller setting. The gate open lag time is the time gap between the beginning and the end of gate open. In this work, the gate open lag time was measured in various conditions. Melt temperature influences the gate open lag time with the shear force on the gate pin surface. The gate open lag times were not same as the others, and the average time was about 200 msec, which was almost 10% of the filling time. The gate open lag time did not show a noticeable change in the stabilized continuous process. To adjust the moment of gate open, the gate open lag time can be applied to the sequence controller setting. However, the moment of gate open should be properly determined because it influenced the halo surface defect, especially on the polished surface. Possibility of the surface defect could be checked by CAE simulation. It is desirable to reduce the flow front speed change when a gate opens.


10:00 am – 10:30 am:
Injection Molding Setup by Means of MachineLearning Based on Simulation and Experimental Data

Julian Heinisch, Institute of Plastics Processing (IKV) in Industry and the Skilled Crafts at RWTH Aachen University
The process setup in injection molding is a recurring task, which is essential for the product quality and the productivity of the process. In the industrial environment, the setup process still mainly relies on the knowledge and intuition of the machine operator, who sets up the process in a trial and error approach using expensive and time-consuming experiments. Machine learning offers the possibility to optimize and systemize the setup process in injection molding. However, machine learning methods, such as Artificial Neural Networks, need experimental data obtained in injection molding trials as a basis. Since the trials are also time-consuming and expensive, these methods could not be established in an industrial injection molding production yet. Besides the optimization based on experiments, an optimization of the machine setup can be performed based on data determined by numerical simulations. Because of the inevitable gap between the prediction of the simulation and the corresponding results at the machine, further experimental optimization at the machine is nevertheless required. Consequently, a combined machine learning approach using neural networks with simulation and experimental data is analyzed. Six setting parameters of two injection molded parts are varied in simulations and experiments and the effects to specific quality criteria, such as part weight and dimensions, were examined. To identify a suitable structure of neural networks for this data basis, neural networks are trained separately based on simulation and experimental data first. Neural networks with 3 to 6 neurons proved well-suited to model the relationships between setting parameters and single quality criteria. On this basis, a combined learning approach using a pre-training of the neural networks with simulation data and a consecutive refinement with little experimental data is implemented. When only few experimental data are used, the model quality can be improved by a pre-training with simulation data. Nevertheless, the improvements are comparatively small and additional combined training concepts need to be analyzed.


10:30 am – 11:00 am:
Study on an Optical Evaluation of Surface Adhesion in the Multilayer Injection Molding Process

Byungohk Rhee, Ajou University
To reduce production time of thick walled parts such as optical lenses, the multilayer injection molding has been developed. In the optical applications, surface adhesion quality between layers should be sufficient. To evaluate the surface adhesion a mechanical strength test was used. However, mechanical strength test has a limitation to evaluate the surface adhesion quality. In this work, an optical evaluation method is proposed to quantify the surface adhesion quality of multilayer injection molded optical parts. It measures light intensity change by light scattering at inter-layer surface. Feasibility of the optical evaluation method as a reliable evaluation tool was examined with specimens ground by sand papers to alter surface roughness. As surface roughness increases, the light intensity increases. Also, it showed a high intensity at an inter-layer surface made by insufficient diffusion. As well as surface roughness of the first layer, influence of processing conditions to surface adhesion were examined. However, no processing conditions showed a noticeable influence.


11:00 am – 11:30 am:
Modeling of the Ultrasound-assisted Ejection in Micro Injection Molding

Giovanni Lucchetta, University of Padova
In this paper, an ultrasound-aided ejection system was designed and tested for various polymers and mold topographies. The use of ultrasound vibration aims at decreasing the ejection friction by reducing its adhesion component, which is controlled by the real contact area developed in the filling phase of the injection molding process. The experiments indicate that the ultrasound vibration reduces the ejection friction up to a maximum of 16%. The effect depends on the polymer used and it increases for rougher mold surface. Moreover, the dependence of ejection friction on mold surface roughness, melt viscosity and elastic modulus at ejection was modeled using the experimental data.