1:30 pm – 7:00 pm:
W11-Additive Manufacturing: Simulation, Materials and Processes
(Moderators: Rabeh Elleithy and Ray Pearson)-Room S320E


 1:30 pm – 2:00 pm:
A closed form solution for predicting final part strength of fused deposition modeling

Steven Devlin, Extension Business and Communities Development Program Senior Director and Assistant Dean for Industrial Engagement, University of Missouri
This article reviews the development of a molecular healing model coupling squeeze flow and intermolecular diffusion to predict final part strength of thermoplastic parts created using fused filament fabrication (FFF). Additive manufacturing (AM) is an innovative group of technology processes with the potential to help companies design products that meet specific customer requirements. In this research, an experimental study and numerical modeling were developed and utilized to drive and validate a closed form heat transfer solution for FFF processes. Parts were printed from polylactic acid (PLA) at various temperatures and print speeds and tested for tensile strength. These strengths were then used to validate the model. It was found that the coupled model was in good agreement with 2:00 pm – 2:30 pmexperimental values for a wide range of extrusion temperatures and higher head speeds.


2:00 pm – 2:30 pm:
3D Printing Process Simulations and Their Applications

Prasad Dasappa, SABIC
The technology for Additive Manufacturing (AM) simulations has improved greatly over recent years with process simulations being the focus. Since warpage and residual stresses are the main challenges faced in AM, especially for large format printing, process simulations are typically used to predict these. However, such process simulations can be used for other applications as well. For example, the ability to predict if a part can be printed without supports is important especially for single nozzle and large format printers. Including gravity loads and appropriate material properties in the simulation can help predict if a part can be printed within the dimensional tolerance without supports. Furthermore, any process change hypotheses to improve this can also be tested using simulations. Virtual DOE’s can also be conducted to optimize process parameters and/or predict material properties required to obtain optimal performance, both from the process as well as from the part during use phase. Performing process simulations on representative volume element can provide insights into effect of defects and also allows performance optimization from a micro-mechanical sense. Finally, the results from such simulations can be carried forward to structural simulations where the in-use scenarios can be tested. Other applications of predictive engineering tools can also be thought of and demonstrated. The final objective of these simulations would be to get a part printed right, the first time.


2:30 pm – 3:00 pm:
Characterization and Mechanical Behavior of SLS processed PA11/CB Nanocomposites

Gabrielle Esposito, Graduate Student, Lehigh University
Selective laser sintering (SLS) continues to be a promising additive manufacturing process, in which three dimensional shapes are produced through laser sintering and resurfacing of a powder bed. Our short term goal is to better understand the structural changes of a polyamide 11/carbon black (PA11/CB) powder during a UV-laser sintered printing process, and ultimately serve as a benchmark for a PA11/CB/nanosilica nanocomposite printed material. Differential Scanning Calorimetry (DSC) confirmed changes in melting temperature between the virgin and printed PA11/CB, decreasing from 201⁰ to 191⁰ C after printing. X-ray diffraction (XRD) and small angle x-ray scattering (SAXS) show a reduction in lamellae thickness from 3.847 nm to 2.001 nm upon printing with no discernable change in crystalline phase. Rheology and solution viscometry tests confirmed a hypothesized increase in viscosity and thus molecular weight during printing, through a post-polymerization process. The printing process has been optimized to produce samples with a 1.8 GPa modulus, ultimate tensile strength of 55 MPa, strain to break of 66 % and essential work of fracture of 24.7 kJ/m2.


3:00 pm – 3:30 pm:
Process impact of Elliptic Smoothness and Powder Shape Factors on Additive Manufacturing with Laser Sintering

Marc Vetterli, Inspire Ag Icams
As of today, polyamide 12 covers approximatively 90% of the commercially and industrially relevant Laser Sintering (LS) materials. To ensure a reasonable growth of the LS market, new materials must be developed to enlarge the material portfolio. However, the design of novel LS materials is critical as they need to fulfil several criteria. Besides suitable intrinsic properties of the polymer like correct thermal, rheology and optical behaviour, the constitution of the powder and the particles are decisive for a successful processing. This article presents the advances done in the field of particle form characterization for LS powders and their impact on LS processability. By using a trio of form factors, the powder flowing behaviour can be accurately predicted and hence enables to screen potential LS materials on a reproducible and reliable way.


3:30 pm – 4:00 pm:
Fundamental Characterization of CLIP 3D Printed Materials

Danielle Grolman, United Technologies Research Center
Advanced additive manufacturing techniques have generated widespread interest as a promising route to produce end-use quality parts with customizable and complex designs that would otherwise be impractical by traditional manufacturing methods. However, a fundamental understanding of printing materials with respect to their impact on process parameters and ultimate properties must be matured to enable optimization of additive manufacturing technologies to achieve end-use quality and performance. To this end, an in depth study of the printing, cleaning, and curing processes associated with stereolithography (SLA) resins in general and dual cure SLA resins specifically is investigated over a range of polymer resins by varying design parameters, build orientations, and post-curing procedures. The post-processing evaluation includes investigation into the isotropic characteristics and homogeneity of the material with respect to the build directionality. Material property characteristics such as mechanical performance at post-cured states and intermediate curing stages (i.e. green state) are studied via thermomechanical analysis and discussed in further detail.


4:00 pm – 4:30 pm:
3D Printed Tooling Solutions

Venkatesha N, SABIC
Additive Manufacturing is a fast emerging disruptive technology that has potential to redefine the conventional manufacturing processes and supply chain management globally in the future. The fundamental principle of this technology is to build the three dimensional objects directly from the 3D computer models in a layer by layer additive manufacturing process. This technology can be leveraged to create prototypes, functional parts, tools and to produce production end user parts in plastic and metal materials. This technical paper will discuss the potential of AM technologies for polymer processing industry and the new space it provides for innovative thinking in plastic application development and the related tooling, without having to worry about any of the conventional manufacturing constraints. At SABIC, printed metal tools for cavities and cores with innovative conformal cooling designs have been utilized for efficient tooling and to improve cycle time. By going one step further additive tooling is integrated with heat & cool processing technology to achieve thin-wall and better quality parts. We will show an example of how such additive tooling was designed and printed, along with the impact on the final part quality. Furthermore, two SABIC resins, ULTEM 9085 resin and ULTEM 1010 resin have widespread adoption in the AM industry. Many customers are installing machines, which run true engineering thermoplastics such as these, and using them to print parts ranging from prototyping, jigs and fixtures, robotic end effectors, and tooling all the way to end use components. We will discuss the use of ULTEM in 3D printed tooling for the polymer processes such as injection molding and thermo-forming. Also, we will review our internal capabilities in design & simulation techniques to optimize tooling for minimum material, less printing time and lower system cost with couple of examples.


4:30 pm – 5:00 pm:
Investigation of A Novel Additive Manufacturing Technique “4D-RheoPrinting” For the Manufacture of Enhanced Polymeric Products

Alaauldeen Duhduh, Ph.D Student, Lehigh University
This paper discusses a novel additive manufacturing technology called “4D-RheoPrinting” and its application in spatial control of the material properties of additive manufacturing products. The technology was designed and developed to allow precise control over shear rate that a polymer strand undergoes during the 3D printing process, thereby inducing customizable molecular orientation of an individual printed “road”. This ability provides an added dimension to the conventional dimensional accuracy goal in 3D printing. Molecular orientation and crystallinity have shown to significantly influence mechanical, optical, thermal, and biodegradation properties of polymeric materials [1]. This work focuses on manipulation and control of shear rate using the RheoPrinting technique in order to print parts with tunable thermal, mechanical and biodegradation properties.


5:00 pm – 5:30 pm:
Critical Capillary Number in a Hyperbolic Converging Nozzle for Polymer Based Additive Manufacturing

Aditya Sangli, University of Maryland, College Park
Use of immiscible liquids in a polymer based additive manufacturing method is explored. A scaled up version of a converging hyperbolic nozzle is built, and the deformation seen by a droplet of Silicone oil in a bulk fluid of Castor oil is observed. Two different droplet injection positions in the channel are explored. Simulation studies showed the existence of pure extension along the center line and a combined shear and extensional effect in the offset position. Non-dimensional plots of deformation measures vs. Capillary number showed an asymptotic trend towards a critical Capillary number for the centerline experiments. Offset deployment experiments resulted in a large degree of droplet stretch. These results advance our understanding of immiscible liquid behavior in hyperbolic converging nozzles for additive manufacturing applications.


5:30 pm – 6:00 pm:
Material Selection, Testing and Validation of Additively Manufactured Components

Johannes Wiener, Montanuniversitaet Leoben
In order to successfully develop a structurally loaded component via additive manufacturing it is necessary to include several vital aspects. Currently, most attention is given to the geometrical reproduction of a design with as little deviation as possible. While for parts produced purely for aesthetic reasons or display this may be sufficient, it can lead to poor results for components used in structural or medical applications. Therefore, a careful material selection, rigorous testing and validation have to accompany the whole process, from the idea to the final component. This work presents an overview over the most important aspects that have to be considered for the material selection and testing in extrusion-based additive manufacturing of structural parts.


6:00 pm – 6:30 pm:
3D Printed Metal Tool for Efficient Injection Molding

Venkatesha N, SABIC
Additive Manufacturing (AM) is a fast emerging disruptive technology that has potential to redefine the conventional manufacturing processes and supply chain management globally in the future. The fundamental principle of this technology is to build the three dimensional objects directly from the 3D computer models in a layer-by-layer additive manufacturing process. This technology can be used to create prototypes, functional parts, tools and to produce production end user parts in plastic and metal materials. This technical paper will discuss the potential of AM technologies for polymer processing industry and the new space it provides for innovative thinking in plastic application development and the related tooling. At SABIC, metal tools have been 3D printed for cavities and cores with innovative conformal cooling designs. This has helped in improving the efficiency of injection molding process and thus reduced the cycle time. By going a step, further additive tooling was also integrated with heat & cool processing technology to achieve thin-wall molding and better quality parts. We will highlight the benefits of 3D printed tooling in achieving efficient injection molding process with an example case study.


6:30 pm – 7:00 pm:
Investigation of Selective Laser Sintering Parameters on the Tensile Properties of Polyamide-11

Gabrielle Esposito, Graduate Student, Lehigh University
Selective laser sintering (SLS) is a rapid developing additive manufacturing process. It produces parts by selectively sintering powder together in a layer-by-layer mode. SLS processing behavior was investigated with a desktop printer (equipped with a 2W UV laser) on a commercial polyamide-11/carbon black (PA11/CB) powder. By systematically increasing the laser energy received by powder (by varying laser speed and laser hatch spacing), we successfully mapped out the laser settings needed to print parts with a reasonable amount of strength and ductility. Therefore, our low power 2 watt UV-laser successfully sintered PA11/CB tensile specimens. These PA11/CB specimens yielded at 53 MPa and elongated up to 65% before fracturing.