SPE Library

The SPE Library contains thousands of papers, presentations, journal briefs and recorded webinars from the best minds in the Plastics Industry. Spanning almost two decades, this collection of published research and development work in polymer science and plastics technology is a wealth of knowledge and information for anyone involved in plastics.

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Conference Proceedings

High Impact Strength Polycarbonate Filament For Additive Manufacturing
Sarah Grieshaber, May 2018

Fused filament fabrication (FFF) is an additive manufacturing technology that uses thermoplastic filament extrusion to build part designs that are often not achievable through other methods such as injection molding. However, the filament material types available for use in FFF on industrial and desktop printers are limited, and mechanical properties such as impact strength can be significantly lower than properties of injection molded parts. This presentation will focus on polycarbonate-based materials used for achieving improved notched Izod impact strength up to four times higher than parts printed with existing filaments at 23 °C and up to three times higher at -30 °C, while maintaining other mechanical properties as well as the ability to function with existing polycarbonate support materials and printer settings. The improvements in impact strength allow this material to be considered for tooling, guides, and fixtures in the automotive and aerospace markets as well as end use parts that require practical toughness during use. An additional benefit for part manufacturers is the potential to reduce part failures during support removal and secondary operations.

A Closed Form Solution For Predicting Final Part Strength Of Fused Deposition Modeling
Steven Devlin, May 2018

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 experimental values for a wide range of extrusion temperatures and higher head speeds.

Influence Of The Layer Time On The Resulting Part Properties In The Fused Deposition Modeling Process
Frederick Knoop, May 2018

The Fused Deposition Modeling (FDM) process by Stratasys is an additive manufacturing (AM) technique that can be used to produce complex thermoplastic parts without the need of a forming tool. A big challenge of this process is that there are several influencing factors with unknown effect on the resulting part properties. One of these factors is the layer time. The aim of this study is to examine the influence of the layer time on the resulting dimensional accuracy and mechanical properties of FDM components manufactured with the amorphous polymer ABS-M30. For this purpose a special job layout was designed to vary the layer time within a certain range. The investigations in this paper show a significant influence on the dimensional accuracy and also on the mechanical properties.

Assessing The Performance Of Continuously Reinforced Acrylonitrile Butadiene Styrene With A Thermotropic Liquid Crystalline Polymer In Fused Filament Fabrication
Mubashir Ansari, May 2018

This work is concerned with the processing of wholly thermoplastic and continuously reinforced filaments in Fused Filament Fabrication (FFF), a form of extrusion based Additive Manufacturing (AM). Acrylonitrile Butadiene Styrene (ABS) was continuously reinforced with a Thermotropic Liquid Crystalline Polymer (TLCP), composed of terephthalic acid (TA), 4-hydroxybenzoic acid (HBA), hydroquinone (HQ) and hydroquinone derivatives (HQ-derivatives), using a novel dual extrusion system. The processing conditions for FFF were determined by performing dynamic mechanical analysis on the pure TLCP. Rectangular specimens were printed using the reinforced filaments with all the roads aligned in one direction. Tensile testing was performed on the filaments as well as the printed specimens to determine improvement in the mechanical properties.

How To Approach Material Validation For Production Parts
Mike Vasquez, May 2018

As more organizations incorporate additive manufacturing systems to produce production parts, it is becoming clear that successfully moving beyond prototyping requires a more advanced and thoughtful material's strategy. To achieve the desired outcomes, organizations now need to learn how to build a methodical and scalable system for measuring and characterizing materials that are going into your processing systems. This talk will discuss best practices and standards for developing and executing a successful strategy for both metals and polymers -- from benchmarking properties, to creating appropriate operating/storage instructions, to testing and then ultimately tracking the lifecycle of materials throughout your production workflow.

3D Printed Capsules For On-Site Formulations
Derrick Smith, May 2018

Drug Product development is a long and expensive process which eventually translates into a higher cost to the payer. Thus, any opportunity to reduce the development timeline is beneficial for the company and the patients. Here, a novel 3D printed (3DP) capsule strategy is disclosed which we believe could enable more informed drug product development with potential to positively impact development timelines. To print these small images, software engineering is required to manufacture defect-free capsules. Additionally, further consideration may be required beyond the normal processing conditions of temperature, speed and quench rate, to realize robust capsules. These capsule walls can be varied to result in burst releases with controlled delay times ranging from immediate to up to 2.5 hours.

Ensuring Mechanical Reliability Of Additively Manufactured Parts Through Testing And Simulation
Mark Oliver, May 2018

Additively manufactured polymers are increasingly being used in mechanically demanding applications. As this trend accelerates, engineers will need to be able to better predict the deformation and failure of polymeric AM materials in service. This involves understanding the properties that often govern failure (fracture, fatigue, creep, etc.) as well as being able to accurately simulate part deformation using finite element analysis.In the first part of this talk, I will discuss how to predict mechanical behavior of polymeric AM parts using non-linear finite element analysis. I will discuss how to measure mechanical behavior, calibrate anisotropic material models, and validate those models using a case study of simulating the strength of a polymeric AM part designed using topology optimization.The second part of my presentation will focus on fatigue and fracture of AM polymers. These properties are not often listed on data sheets but are critical to engineering reliable parts for structural applications. I will present some of the unique attributes of fracture and fatigue in various AM polymers and share new data on materials processes using MJF, CLIP, and SLS.

To Print Or Not To Print, That Is The Additive Manufacturing Question
Jim Allen, May 2018

Additive manufacturing (AM) is becoming a larger part of manufacturing, particularly plastics and metals. New technologies and new materials are being introduced on a regular basis. In a few short years, AM has become a more accepted way of producing end use parts and not just prototypes. How can companies that produce plastic parts stay ahead of the curve? How do you know when to produce a part additively versus injection molding or other more traditional technique? What if there was a tool that did this automatically? 3YOURMIND has developed the first automated AM analysis platform. Now decades of AM experience are available in a streamlined platform to inform smart 3D production decisions.We will talk about:• The use of quantitative methods for evaluation as a key turning point in AM production• How early adopters are actively integrating this new technology• The potential savings in time and money by automating this process• How we envision automated AM evaluation will shift in the industry in the next 3-5 years

Effective Subtraction Before Additive Manufacturing: The Art Of Leveraging Constraints
Ravi Kunju, May 2018

For highly engineered components, the topological shapes that are generated based on the loads and boundary conditions, can be impacted by the many choices of constraints that are set. Over the years Altair’s Optistruct has developed the broadest set of constraints, and has recently introduced ‘overhang’ constraints for 3D printing so the resulting structure is grown to avoid a specified overhang angle (example: of 45 degrees typically), to minimize areas requiring support. Before embarking on creating a topological shape it is necessary to identify the direction of print, which is a sensitive variable by itself. With a variety of constraints available to a designer, a holistic approach needs to be developed wherein the entire process of manufacturing the part, including post processing operations, are carefully considered including the entire geometry that is printed along with the support structure. A fine balance between the interplay of choosing the right constraints, defining design & non-design space, and the right penalty factors, are critical for generating optimal topological shapes that accommodate, for example: areas for holding the 3D printed part for post-processing; or effectively evacuating the powder in plastic printing; or remove supports in metal printing. In this presentation, examples will be highlighted to showcase how to leverage the latest computational methods to efficiently subtract as much before additively manufacturing components, with a goal to develop an effective and repeatable product design strategy.

Material Selection, Testing And Validation Of Additively Manufactured Components
Johannes Wiener, May 2018

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.

Structure And Property Relationships Of Additively Manufactured Polyphenylene Sulfide With Carbon Fiber Reinforcement
Peng Liu, May 2018

The objective of this work is to investigate the microstructure of carbon fiber (CF) reinforced polyphenylene sulfide (PPS) resulted from extrusion-based large-scale additive manufacturing (AM) process. This study attempts to establish a fundamental understanding on the role of AM process in transferring a set of intrinsic material properties to the macroscopic properties of the final part. Questions on development of morphology focus on polymer crystal orientation and carbon fiber alignment in proximity to the interface of successive layers. Our findings demonstrated that PPS at the interface has lower crystal perfectness compared to the layer region; the carbon fiber shows higher level of preferred orientation at the interface. Successive layers along the building z-direction present lower storage modulus as it is demonstrated in the dynamic mechanical analysis (DMA).

Critical Capillary Number In A Hyperbolic Converging Nozzle For Polymer Based Additive Manufacturing
Aditya N Sangli, May 2018

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 centerline 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

Rheological Characterization And Quality Assessment Of Commercial Abs Filaments For Fused Deposition Modeling
Cybele Lotti, May 2018

Acrylonitrile-butadiene-styrene (ABS) is the most commonly used thermoplastic used for Fused Deposition Modeling (FDM) due to its low cost and good properties. The viscoelastic behavior of five commercial ABS filaments was investigated and compared to quality features of a two-piece printed part. The results that the commercial ABS filaments differ not only with respect to viscosity, but also to relaxation time, recoverable deformation, morphology/composition, and thermal stability. Filaments with lower recoverable deformation tend to present better surface finish regardless the viscosity and relaxation time. Filaments with lower viscosities and faster relaxation times resulted in tight fit due to disproportional variations in the critical dimensions of the printed part.

Process Impact Of Elliptic Smoothness And Powder Shape Factors On Additive Manufacturing With Laser Sintering
Marc Vetterli, May 2018

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.

Strength Analysis Of Fused Filament Fabricated Continuous Carbon Fiber Composite Test Samples
Rogelio Herrera, May 2018

With the use of the Ansys® Workbook program, Markforged® Mark Two fused filament fabrication (FFF) composite samples were subjected to three-point flexural testing, using ASTM D790 standards. The results of flexural testing and the provided data of the mechanical properties of the composite materials were used to develop finite element analysis (FEA) models. The samples were composites of Markforged’s proprietary continuous carbon fiber filament and nylon filament. In comparison between the test results and the FEA models, both composite model methods and isotropic FEA modeling methods resulted in stronger and less flexible mechanical attributes if the proprietary material specifications were used. Through the development and analysis of micrograph samples of the Markforged’s carbon fiber filament (CFF), found that the CFF was only composed of 22.31% a fiber volume content (FVC). With the new FVC data, a more accurate model was possible for a limited range of flexural displacement.

Investigation Of Selective Laser Sintering Parameters On The Tensile Properties Of Polyamide-11
Gabrielle Esposito, May 2018

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.

Investigation Of A Novel Additive Manufacturing Technique “4D-Rheoprinting” For The Manufacture Of Enhanced Polymeric Products
Alaauldeen Duhduh, May 2018

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.

The Opportunity With Direct Digital Manufacturing
Tomeo Wise, May 2018

3D printing is often thought of only during the prototyping phase of product development, but designers and engineers should expect more from the additive technologies and materials available today. By embracing a direct digital manufacturing (DDM) strategy, companies are driving greater innovation, mitigating risk, lowering costs, and gaining agility. DDM enables design freedom, reduces lead times, and allows for more decentralized production, which will have significant impacts on communities across the globe. Ultimately, less rigid development and manufacturing means that more optimized, customized, and specialized products suddenly become viable as the barriers of scale are torn down. In this session, FATHOM will discuss why companies are opting for tool-less manufacturing for end-use products with real world application examples.

The Influence Of Melt Flow Rate And Nozzle Temperature In Fused Filament Fabrication
Nicole Hoekstra, May 2018

This study investigated the influence of the melt flow rate of acrylonitrile butadiene styrene (ABS) and nozzle temperature used in fused filament fabrication (FFF) on layer adhesion and printability. Prediction of the mechanical properties of printed parts, and the optimal process parameters for each material, is an area of continued difficulty. Test specimens were printed using four ABS filaments (representing a range of melt flow rates) at three different nozzle temperatures. Ultimate tensile strength, dimensional accuracy, bridging performance, and surface roughness were investigated using designed experiments. In general, low nozzle temperatures correlated to lower layer adhesion, but higher dimensional accuracy. Build plate position was not a significant factor for horizontal specimens but was for vertical specimens. Bridging performance and surface roughness were not affected by the melt flow index or nozzle temperature.

Mechanical Properties Of 3D Printed Polylactide/Microfibrillated Polyamide Composites
Nahal Aliheidari, May 2018

Fused deposition modeling (FDM) as the most common type of additive manufacturing (3D printing) is experiencing rapid growth. FDM employs thermoplastic-based materials to create complex and three-dimensional objects layer by layer. To expand the applications of FDM for end-use structural and functional products, novel printable materials with enhanced properties must be developed. Polylactide (PLA) has been well established as one of the most common feedstock materials in FDM 3D printing. However, PLA suffers from brittleness, narrow service window, and relatively poor mechanical properties. In this work, we report a printable PLA-based filament reinforced with microfibrillated polyamide-6 (PA6) in an attempt to enhance the mechanical properties of PLA-based prints. The microfibrillated PLA/PA6 fibers were produced by melt mixing followed by a hot stretching process. The filament feedstock was then prepared using a plunger-type extrusion process. Tensile test samples were then 3D printed and tested. The introduction of microfibrillated 3wt.% PA6 resulted in the improvements in the tensile modulus (~35%), tensile strength (~60%), and strain-at-break (~38%), compared to those of the neat PLA samples. The results of this work are highly applicable in developing high-performance printed materials.

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