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In this bachelor thesis, I examine how automation of fused filament fabrication (FFF) can be implemented, and what the limitations are for different kinds of automation solutions for FFF. Fused filament fabrication is a 3D-printing technology where a material is extruded through a nozzle, layer by layer, to create a print. The thesis also provides a calculation for the commercial feasibility of small batch rapid production with the implementation of an automation solution for FFF. The approach was a qualitative study containing five interviews, combined with empirical knowledge and data from the additive manufacturing company Svensson 3D. This was complemented with an analysis of which criteria to use when evaluating FFF automation solutions, and a framework for looking at FFF from an operator perspective. To calculate commercial feasibility of automation solutions for FFF, Internal Rate of Return and Payback Time were used. This resulted in six criteria to evaluate solutions for automation of FFF, three evaluations of problems within three solutions for automation of FFF, and a finding showing that small batch rapid production is commercially feasible with automated FFF. Lastly, the thesis contains a discussion regarding what the future is for FFF, and the limitations of the framework presented for evaluating automated FFF systems. Possible promising solutions for automated FFF are presented, together with ideas for how design for additive manufacturing can help shape the future of automated FFF. / I det här kandidatarbetet undersöker jag hur automatisering inom fused filament fabrication (FFF) kan implementeras, och vad begränsningarna är för olika sorters automatiseringslösningar för FFF. Det läggs även fram en uträkning för den kommersiella gångbarheten för small batch rapid production med implementeringen av ett automatiskt FFF-system. Tillvägagångsättet bestod av en kvalitativ studie baserad på fem intervjuer, kombinerad med empirisk kunskap och data från additiva tillverkningsföretaget Svensson 3D. Det här kompletterades med en analys av vilka parametrar som bör användas för att utvärdera lösningar för FFF-automatisering, och ett ramverk där automatiseringslösningarna betraktas ur ett operatörs-perspektiv. För att räkna ut den kommersiella gångbarheten för automatiseringslösningar av FFF användes internränta och återbetalningstid. Det här resulterade i sex parametrar för att utvärdera automatiseringslösningar för FFF, tre utvärderingar av vilka problem som finns i tre existerande automatiseringslösningar, och slutsatsen att small batch rapid production är kommersiellt gångbart för automatiserad FFF. Slutligen innehåller arbetet en diskussion gällande framtiden för FFF och begränsningarna hos det ramverk som presenterades för att utvärdera automatiserade FFF system. Möjliga lovande lösningar för automatiserad FFF presenteras och hur design för additiv tillverkning kan hjälpa till att forma framtiden för automatiserad FFF.

Consumer additive manufacturing (3D printing) has rapidly grown over the last decade. While the technology for the most common type, Fused Filament Fabrication (FFF), has systematically improved and sales have increased, fundamentally, the capabilities of the machines have remained the same. FFF printers are still limited to depositing layers onto a flat build plate. This makes it difficult to combine consumer AM with other objects. While consumer AM promises to allow us to customize our world, the reality has fallen short. The ability to directly modify existing objects presents numerous possibilities to the consumer: personalization, adding functionality, improving functionality, repair, and novel multi-material manufacturing processes. Indeed, similar goals for industrial manufacturing drove the research and development of technologies like direct write and directed energy deposition which can deposit layers onto uneven surfaces. Replicating these capabilities on consumer 3-axis FFF machines is difficult mainly due to issues with reliability, repeatability, and quality. This thesis proposes, demonstrates, and tests a method for scanning and printing dimensionally-accurate (unwarped) digital forms onto physical objects using a modified consumer-grade 3D printer. It then provides an analysis of the machine design considerations and critical process parameters. / Master of Science / Consumer additive manufacturing (3D printing) has rapidly grown over the last decade. While the technology for the most common type, Fused Filament Fabrication (FFF), has systematically improved and sales have increased, fundamentally, the capabilities of the machines have remained the same. FFF printers are still limited to depositing layers onto a flat build plate. This makes it difficult to combine consumer AM with other objects. While consumer AM promises to allow us to customize our world, the reality has fallen short. The ability to directly modify existing objects presents numerous possibilities to the consumer: personalization, adding functionality, improving functionality, repair, and novel multi-material manufacturing processes. Indeed, similar goals for industrial manufacturing drove the research and development of technologies like direct write and directed energy deposition which can deposit layers onto uneven surfaces. Replicating these capabilities on consumer 3-axis FFF machines is difficult mainly due to issues with reliability, repeatability, and quality. This thesis proposes, demonstrates, and tests a method for scanning and printing dimensionally-accurate (unwarped) digital forms onto physical objects using a modified consumer-grade 3D printer. It then provides an analysis of the machine design considerations and critical process parameters.

Unlike traditional stochastic scaffold fabrication techniques, additive manufacturing (AM) can be used to create tissue-specific three-dimensional scaffolds with controlled porosity and pore geometry (meso-structure). However, due to the relatively few biocompatible materials available for processing in AM machines, direct fabrication of tissue scaffolds is limited. To alleviate material limitations and improve feature resolution, a new indirect scaffold fabrication method is developed. A four step fabrication process is explored: Fused Deposition Modeling (FDM) is used to fabricate scaffold patterns of varied pore size and geometry. Next, scaffold patterns are surface treated, and then mineralized via simulated body fluid (SBF); forming a bone-like ceramic throughout the scaffold pattern. Finally, mineralized patterns are heat treated to pyrolyze the pattern and sinter the minerals. Two scaffold meso-structures are tested: "tube" and "backfill." Two pattern materials are tested [acrylonitrile butadiene styrene (ABS) and investment cast wax (ICW)] to determine which material is the most appropriate for mineralization and sintering. Mineralization is improved through plasma surface treatment and dynamic flow conditions. Appropriate burnout and sintering temperatures to remove pattern material are determined experimentally. While the "tube scaffolds" were found to fail structurally, "backfill scaffolds" were successfully created using the new fabrication process. The "backfill scaffold" meso-structure had wall thicknesses of 470 – 530 µm and internal channel diameters of 280 – 340 µm, which is in the range of appropriate pore size for bone tissue engineering. "Backfill scaffolds" alleviated material limitations, and had improved feature resolution compared to current indirect scaffold fabrication processes. / Master of Science

Effective quality improvement in the manufacturing industry is continually pursued. There is an increasing demand for real-time fault detection, and avoidance of destructive post-process testing. Therefore, it is desirable to employ sensors for in-process monitoring, allowing for real-time quality assurance. Chapter 3 describes the application of sensor based monitoring to additive manufacturing, in which sensors are attached to a desktop model fused deposition modeling machine, to collect data during the manufacturing process. A design of experiments plan is conducted to provide insight into the process, particularly the occurrence of process failure. Subsequently, machine learning classification techniques are applied to detect such failure, and successfully demonstrate the future potential of this platform and methodology. Chapter 4 relates the application of online, image-based quantification of the surface quality of workpieces produced by cylindrical turning. Representative samples of cylindrical shafts, machined by turning under various conditions, are utilized, and an apparatus is constructed for acquiring images while the part remains mounted on a lathe. The surface quality of these specimens is analyzed, employing an algebraic graph theoretic approach, and preliminary regression modeling displays an average surface roughness (Ra) prediction error of less than 8%. Prediction occurs in less than 2 seconds, showing the capability for future application in a real-time, quality control setting. Both of these cases, in additive manufacturing and in turning, are validated using real experimental data and analysis, showing application of sensor-based online process monitoring in multiple manufacturing areas. / Master of Science

Filament-based material extrusion additive manufacturing (MEAM) is an established technique in additive manufacturing (AM). However, semicrystalline polymers, such as polypropylene (PP), have limited commercial use in MEAM processes in the past due to their rapid crystallization kinetics and the subsequent effect on the integrity of the generated structures. The rapid crystallization of PP can be controlled by formulating blends of PP with hydrocarbon resins to enable longer re-entanglement times for interlayer adhesion. While the topic of formulating PP blends/composites with other materials to improve the printability has been investigated, variation in properties of commercial PP grades, of similar molecular weight (MW) and molecular weight distribution (MWD), on printability is still to be investigated. Those commercial PP grades can have wide variation in properties such as Melt Flow Index (MFI), additive content, and polymer architecture which can impact material properties relevant to printability. To investigate the effect of properties of commercial PP on their printability and mechanical performance, different commercial PP grades, with different properties, are blended with a fixed loading of hydrogenated resins, and the consequent effects on the mechanical properties of MEAM generated PP structures are studied via mechanical analysis. Tensile strength and the extent of interlayer adhesion in the 3D printed blends are characterized through rheological measurements. These measurements emphasize the importance of the relative location of the storage/loss modulus crossover point via small oscillatory frequency sweeps. We specifically show that a relatively higher crossover frequency will correlate with improved interlayer adhesion and reduced warpage in printed structures. However, this improvement is accompanied by a tradeoff, resulting in inferior tensile strength and an increased degree of print orientation anisotropy. / Master of Science / Additive Manufacturing (AM), commonly known as 3D printing, is a transformative technology with high potential to revolutionize the manufacturing landscape. Polymers are widely used in AM for various applications. As a result, extensive research is conducted to enhance the printability and properties of printed polymer structures. Polypropylene (PP) exhibits desirable mechanical, optical, and chemical properties that make its use in AM attractive. Despite this potential, optimizing the use of PP in 3D printing remains challenging. Consequently, extensive research is underway to improve the printability of PP. However, the effects of including additives to enhance the properties of commercial PP grades are often overlooked. We demonstrate that the choice of commercial PP grade is crucial to the mechanical and structural properties of structures generated via AM. This was established by developing a systematic experimental procedure to assess the printability of various PP grades and to measure their key mechanical and structural properties.

Yes / Designing and manufacturing functional parts with enhanced mechanical property is a major goal of fused filament fabrication (FFF) for polymeric elastomers, which exhibits major advantages in producing such parts with a range of structures. But the unsatisfactory mechanical performance constrains greatly its real application and there is yet no consensus in the mechanical characterization of printed samples. This work takes the nozzle height as the considered factor and tests the tensile property of FFF-printed thermoplastic polyurethane (TPU). Rheological property of the TPU melt, represented here by die swell behavior and shear viscosity, were measured initially to obtain a preliminary assessment of the material suitability and an optimization of melt extrusion conditions for FFF processing. Then correlation between the cross-section profile of deposited bead and the tensile performance of printed sample were evaluated. Both the shape of deposited bead and the bonding strength of two adjacent beads are emphasized when explaining the measured tensile strength. The significance of molecular permeation efficiency at bead-bead interfaces, and bonding-releasing patterns between adjacent beads to the tensile failure of printed objects is discussed. / The support provided by China Scholarship Council (CSC, 201806465028) for Xiang Lin during his academic visit in University of Bradford is acknowledged.

The specific goal of this investigation was the determination of the self-diffusion coefficient of the divalent lead ion in a fused lead chloride system at several temperatures and the determination of the activation energy for the diffusion process.

Extrusion additive manufacturing technologies may be utilized to fabricate complex geometry devices. However, the success of these additive manufactured devices depends upon their ability to withstand the static and dynamic mechanical loads experienced in service. In this study, quasi-static tensile and cyclic fatigue tests were performed on ULTEM 9085 samples fabricated by fused deposition modeling (FDM). First, tensile tests were conducted following ASTM D638 on three different build orientations with default build parameters to determine the mechanical strength of FDM ULTEM 9085 with those supplied by the vendor. Next, different build parameters (e.g. contour thickness, number of contours, contour depth, raster thickness, and raster angle) were varied to study the effects of those parameters on mechanical strength. Fatigue properties were investigated utilizing the procedure outlined in ASTM D7791. S-N curves were generated using data collected at stress levels of 80%, 60%, 30% and 20% of the ultimate tensile stress with an R-ratio of 0.1 for the build orientation XZY. The contour thickness and raster thickness were increased to 0.030 in. to determine the effect of those two build parameters on tension-tension fatigue life. Next, the modified Goodman approach was used to estimate the fully reversed (R=-1) fatigue life. The initial data suggested that the modified Goodman approach was very conservative. Therefore, four different stress levels of 25%, 20%, 15% and 10% of ultimate tensile stress were used to characterize the fully reversed fatigue properties. Because of the extreme conservatism of the modified Goodman model for this material, a simple phenomenological model was developed to estimate the fatigue life of ULTEM 9085 subjected to fatigue at different R-ratios. / Master of Science / Additive manufacturing (AM) is a revolutionary technology that is dramatically expanding the current manufacturing capabilities. The additive process allows the designers to create virtually any geometry by constructing the parts in layers. The layer-to-layer build technique eliminates many of the limitations imposed by traditional manufacturing methods. For example, machining is a common manufacturing technique that is used to create highly complex parts by removing material from a billet. The process of removing material to create a part is called subtractive manufacturing. Subtractive manufacturing requires sufficient clearance for tool access, in addition to complicated mounting fixtures to secure the part. These constraints often force engineers to design less optimized geometries to account for the manufacturing limitations. However, additive manufacturing allows the user greater design freedoms without a significant increase in resources. This innovative construction technique will push the boundaries of cutting-edge designs by removing many restrictions associated with traditional manufacturing technologies. Additive manufacturing is a relatively recent technology that evolved from rapid prototyping techniques that were developed in the 1960s. Rapid prototyping is used to create rapid iterations of physical models. However, additive manufacturing aims at creating functional end-use products. The layer-to-layer build process still poses many research challenges before it will be accepted as a reliable manufacturing technique. One of the current limitations with AM technologies is the availability of material properties associated with AM materials. The layer-to-layer build process and the toolpath creates different material properties that are dependent on the orientation of the applied load. Thus, further research is recommended to provide designers with a greater understanding of the mechanical characteristics of additive manufactured materials such as ULTEM 9085. This objective of this research is to characterize the static strength and fatigue characteristics of ULTEM 9085. The first part of the thesis focused on investigating the effects of the following build parameters on the strength of the component: build orientation, contour thickness, number of contours, contour depth, raster thickness, and raster angle. The second portion of this investigation determined the effects of fluctuating loads on the fatigue life of ULTEM 9085. Overall, the results of this investigation can be used to design more effective components using extrusion additive manufacturing technologies.