8:00 am – 11:30 am:
T5-Joining of Plastics and Composites
(Moderator: Phil Bates)-Room S320H

8:00 am – 8:30 am:
Improvement on Fatigue Performance of Metal-Composite Friction Spot Joints Based on the Weld-Bonding Concept

Natalia Manente Andre, Helmholtz-Zentrum Geesthacht
This work investigates the potential of the Weld-Bonding concept to improve the fatigue performance of friction spot joints. Therefore, friction spot joints of AA2024-T3/CF-PPS (carbon-fiber-reinforced polyphenylene sulfide) were produced with an additional thermoplastic film interlayer. Two joining conditions manufactured with low and high heat inputs were investigated. The fatigue performance of those joints was evaluated at 35%, 50% and 75% of their respective ultimate lap shear force (ULSF). It was observed that process-related microvoids decreased the fatigue strength of the joints in high cycle fatigue (HCF). Superior fatigue life of the joints with interlayer in comparison with those without interlayer was observed. At 105 cycles, typical qualification requirement of the aircraft industry, the interlayer joint showed fatigue strength of 51% of ULSF, whereas the fatigue strength of the joint without interlayer was 37% of ULSF. In the whole spectrum, the joint with interlayer showed a fatigue life approximately four times higher than the joint without interlayer.

8:30 am – 9:00 am:
Direct-Friction Riveting of Metal-CFRP Overlap Joints

Natascha Zocoller Borba, HZG
Friction Riveting is an innovative and promising joining technology, which can potentially fulfill the industry requirements for sustainable and efficient systems. The objective of this work is to prove the feasibility of Direct-FricRiveting by inserting a metallic rivet through metal-composite overlapped plates and subsequent anchoring in the composite part, which is a challenging configuration with limited knowledge available. The case-study joint configuration used in this work comprised a Ti6Al4V rivet, which joined an overlapped AA2024-T3 upper plate with a 30% short-carbon-fiber-reinforced poly-ether-ether-ketone lower plate, material combination of high interest for the aircraft industry. Evaluation of joint formation, temperature development, microstructural and physicochemical changes in the composite, and mechanical properties were carried out for joints produced under low and high energy input. The feasibility was proved, showing satisfactory mechanical performance under lap shear testing (up to 7 ± 1 kN). Changes of polymer crystallinity and thermo-mechanical decomposition in the composite were shown not to affect the joint mechanical performance and failure behavior, while the plastic deformation at the rivet tip played the major hole. The knowledge gathered in this preliminary work will be further applied to optimize the process, contributing to the development of the Friction Riveting technology and improvement of its industrial applicability.

9:00 am – 9:30 am:
Experimental Investigation of Amplitude Transmission in Ultrasonic Welding of Thermoplastic Composites

Genevieve Palardy, Louisiana State University
Ultrasonic welding is an efficient technique for rivetless assembly of thermoplastic composites. To further improve this process, it is necessary to develop numerical simulations. A phenomenon often misevaluated but crucial for accurate process simulations is hammering. It is the loss of contact between sonotrode and upper adherend during the vibration phase. The goal of this paper is twofold: present an experimental procedure to measure the displacement of the sonotrode and upper adherend during welding, and discuss two strategies to quantify amplitude transmission to the upper adherend. This will lead to improvement of predictive models for ultrasonic welding and closer agreement with experimental data.

10:00 am – 10:30 am:
Time-Dependent Vibration Welding Behavior of Foam Injection Molded Parts in Consideration of Various Fiber Reinforcements and Joint Types

Dario Heidrich, Chemnitz University of Technology
Due to the rising demand of lightweight constructions as well as saving material, the density and weight of thermoplastic parts can be influenced significantly by using the thermoplastic foam injection molding process. The characteristic three-layer structure which is originated by the foam injection molding, a microcellular foamed core is surrounded by a non-cellular skin layer, results in a weight saving and leads to an increased specific bending stiffness with a simultaneous low tendency to warp. Whereas the established welding processes for solid parts have already achieved a high degree of perfection within the last decades, the joining of microcellular thermoplastics is a novel. The structure as well as the remaining foaming agent within the part represents a challenge for welding, which can cause great difficulties in the process. Unfortunately, there are no standards or experiences for welding such foamed parts yet. The present investigation researched the welding behavior of foam injection molded parts in comparison to their solid counterpart in dependence on fiber reinforcement and joint type. In contrast to solid parts, the welding behavior shows a significant time-dependence in case of foam injection molded parts for the various materials.

10:30 am – 11:00 am:
Infrared Welding of Highly Filled Graphite Composites

Martin Facklam, Institute for Plastic Processing
Beside the economical production of bipolar and heat exchanger plates made from graphite composites, the stack assembly is of great importance for the further technological development of fuel cell, redox-flow battery and heat exchanger systems. In order to choose a suitable welding method, to evaluate the weldability of the composites and to produce a secure stack assembly, a comprehensive understanding of the welding behavior of the materials is required. This work focuses on the welding of graphite composites using the infrared welding method. To form a material-locking joint during the welding process, a defined melting of the material in the joining area is decisive. Due to the thermal properties of highly filled graphite composites, the welding process differs fundamentally from conventional welding of unfilled or low-filled thermoplastics. To perform a scientific examination of the material heating depending on the heating source, a surface and a contour-following infrared radiator were used. Independent of the radiator type, no high-quality joining connection could be achieved. Due to the high thermal conductivity and the low heat capacity of the graphite compounds, the joining area does not have a sufficiently high temperature after infrared heating. Furthermore, it is not possible to apply a sufficiently high joining force, as deep material heating takes place. As a result, the formation of a material-locking joint is significantly impaired with an increasing graphite content.

11:00 am – 11:30 am:
Infared Welding of Continuous Glass Fiber-Reinforced Thermoplastics — Approaches to Use the Fibers in the Joint

Marios Constantinou, Chemnitz University of Technology
Thermoplastic prepregs that are also known as organo sheets are processed in presses and formed to half shells. Larger components can be produced by joining the half shells, which results in hollow bodies. However, current manufacturing technologies allow only cap profile shaped joints, which cause fiber deflections in the joint plane. This paper shows that overlapping infrared welds in organo sheets enable weld strengths close to the interlaminar shear strengths of the unwelded materials and thus a fiber utilization across the joint plane. By using high welding pressures, a matrix depletion and a change of the fiber alignment in the weld plane may occur which causes low weld strengths. Therefore, criteria for the successful welding were defined various possibilities to the optimization of the weld strengths were investigated.

8:00 am – 8:30 am:
T6-Medical Plastics/Injection Molding Joint Session: Processing of Medical Plastics
(Moderator: Maureen Reitman)-Room S320F

8:00 am – 11:30 am:
KEYNOTE: Innovations in Plastics Processing for Healthcare Applications

Manish Nandi, SABIC
As medical device manufacturers are developing new products, they are considering critical healthcare imperatives – reducing costs and improving patient outcomes. Fortunately, several new technologies are giving device designers the tools they need to address these challenges. Among them are advanced thermoplastic resins and composites – materials that can contribute to the effectiveness of new technologies and manufacturing techniques for tomorrow’s innovative devices. Microneedles Microneedle arrays are developed for reduced pain and efficient drug delivery without using a cold chain. The focus of the presentation will be on applying micro injection molding for creating engineering thermoplastic based microneedle arrays which will be further mechanically tested. The micro molding tool holds the reverse geometry of ten different microneedles. The needles on the array are divided into two different lengths: 1 mm and 0.8 mm. The base of the half-pyramid shaped needle varies, which allows one to obtain different aspect ratios of the needle, resulting in a different cutting behavior when applied to the skin. Altogether, the array holds 100 needles (10 different geometries and 10 per row) on a surface of 1 cm2. Screening the processing behavior of different polymer grades was performed using the microneedle tool together with a micro injection molding machine. A design of experiment was performed using five grades (PC, PPE, PC/ABS, ABS and LCP). The selection of grades was conducted on the basis of high shear viscosity measurements which were performed before molding. As a result of the molding investigations, two (PC and PPE) out of the five materials fulfill the set criteria and were used for mechanical testing as well as for pig skin penetration studies (without drug coating). Mechanical characterization consists of nano indentation tests where the needle tip is deformed along a defined length (80 μm) and the force needed to reach this deformation was measured. Skin penetration tests were performed on an abdominal skin from a young swine. The results of the mechanical tests and skin penetration tests indicate that two (15° angle; 0.8 mm and 1 mm in length) out of the ten microneedle geometries could be used for a further scale up scenario of arrays which can hold several hundreds of needles. Microneedle patches obtained have a tip radii below 10 μm. The results indicate that using the approach of micro molding and testing, a choice of necessary needle length, tip sharpness, proper penetration of skin, and polymer can be made. Recent developments demonstrate that commercialization of polymer based microneedle systems is feasible. Microfluidics Integration of a complete diagnostic lab onto a credit-card sized chip requires micro-channels to handle small volumes of fluids. Initially, silicon chip technology was used to create microfluidic devices, but that posed some process limitations with respect to cost and cycle times. Another technique frequently used is soft lithography. However, this method has some limitations on the device design and manufacturing. More advanced technologies use injection molding to fabricate two or more separate parts that require post molding operations. These parts are then stacked and sealed to each other, making the device fit for service. In other applications, the injection molded part containing the microfluidics channels is sealed off by applying tapes on the half open channels. SABIC is currently researching whether “hesitation”, which is an unwanted effect resulting in typical injection molding defects, can be used to create structures with closed and sealed micro channels under the surface. This method of chip production may increase production speed since secondary operations such as positioning, sealing, clamping or welding, are no longer required.

8:30 am – 9:00 am:
KEYNOTE: New Developments and Trends in Medical Extrusion

Steve Maxson, Graham Engineering
This presentation will focus on new developments in medical device technology that is driving the trends in medical extrusion technology. This includes more complex multi-layer extrusions for infusion and interventional delivery systems. The increased demand for miniature tubing and how the reducing the polymer pellet size can enable higher performance and improved dimensional stability especially for low-profile PA12 balloon tubing. The presentation will also discuss advancements in multi-layer anti-microbial tubing to reduce the frequency of Healthcare-Associated Infections (HAIs).

9:00 am – 9:30 am:
Laser-based Processing of Polymers for Medical Applications

Roger Narayan, NC State University
Laser-fabricated structures, including tissue engineering scaffolds, implantable sensors, and drug delivery devices, will become important tools for medical treatment over the coming decades. Over the past decade, we have examined use of several laser technologies, including pulsed laser deposition, matrix assisted pulsed laser evaporation, pulsed laser deposition, laser induced forward transfer, and two photon polymerization, to prepare microstructured and nanostructured polymers for medical applications. For example, we have shown that a laser-based approach known as two photon polymerization may be used to process a variety of photosensitive polymers into medically-relevant structures. We have also used laser ablation approaches such as matrix assisted pulsed laser evaporation and pulsed laser deposition to create nanostructured polymer films Efforts to improve the biocompatibility of laser-processed polymers and modify laser methods for clinical translation will be considered.

9:30 am – 10:00 am:
Micro Molding Drug Delivery Devices to Micron Tolerances

Donna Bibber, Vice President, Isometric Micro Molding, Inc.
Micro molding drug delivery devices to micron tolerances requires extreme fine tuning of existing injection molding technologies. Unlike conventional or macro molding, micron tolerances require unconventional tooling, molding, automation, and metrology practices to achieve Cpk of 1.33 or better. This paper identifies and analyzes these 4 key factors to molding parts to micron tolerances: 1. Tooling precision 2. Micro Molding Process Control 3. Micro automated assembly 4. CT scanning metrology Case studies of micron tolerances for implants and drug delivery devices (transdermal patches, injection, and slow release devices) will be presented.

10:00 am – 11:30 am:
PANEL: Part Process Development and Validation for Multiple Machines

Matthew Therrien, RJG, Inc., Rod Brown, Greg Lusardi, Paul Robinson, Brad Smith,Ed Valley, Scott Scully, Director, Corporate Molding/Tooling, Terumo Cardiovascular Group
“Part Process” Development and Validation for Multiple Machines: A Medical Device OEM Consortium formed to challenge the traditional plastic part validation process to facilitate moving a mold between machines – from Validation into Production. Much has been written and said regarding the “what and how-to” as it relates to process development and moving a mold between machines for the medical device industry. The Consortium member panel executed it – the economics of adopting this approach could potentially not only save tens to hundreds of thousands of dollars for each move (depending upon the number of molds), but the speed-to-market advantages and operations flexibility would be simply invaluable.