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This thesis presents a model for the procedures of manufacturing Fused Filament Fabrication (FFF) components by calculating required process parameters using empirical equations. Such an empirical model has been required within the FFF field of research for a considerable amount of time and will allow for an expansion in understanding of the fundamental mathematics of FFF. Data acquired through experimentation has allowed for a data set of geometric characteristics to be built up and used to validate the model presented. The research presented draws on previous literature in the fields of additive manufacturing, machine engineering, tool-path programming, polymer science and rheology. Combining these research fields has allowed for an understanding of the FFF process which has been presented in its simplest form allowing FFF users of all levels to incorporate the empirical model into their work whilst still allowing for the complexity of the process. Initial literature research showed that Polylactic Acid (PLA) is now in common use within the field of FFF and therefore was selected as the main working material for this project. The FFF technique, which combines extrusion and Computer Aided Manufacturing (CAM) techniques, has a relatively recent history with little understood about the fundamental mathematics governing the process. This project aims to rectify the apparent gap in understanding and create a basis upon which to build research for understanding complex FFF techniques and/or processes involving extruding polymer onto surfaces.

This thesis presents a model for the procedures of manufacturing Fused Fila ment Fabrication (FFF) components by calculating required process parameters using empirical equations. Such an empirical model has been required within the FFF field of research for a considerable amount of time and will allow for an ex pansion in understanding of the fundamental mathematics of FFF. Data acquired through experimentation has allowed for a data set of geometric characteristics to be built up and used to validate the model presented. The research presented draws on previous literature in the fields of additive manufacturing, machine engi neering, tool-path programming, polymer science and rheology. Combining these research fields has allowed for an understanding of the FFF process which has been presented in its simplest form allowing FFF users of all levels to incorporate the empirical model into their work whilst still allowing for the complexity of the process. Initial literature research showed that Polylactic Acid (PLA) is now in common use within the field of FFF and therefore was selected as the main working mate rial for this project. The FFF technique, which combines extrusion and Computer Aided Manufacturing (CAM) techniques, has a relatively recent history with lit tle understood about the fundamental mathematics governing the process. This project aims to rectify the apparent gap in understanding and create a basis upon which to build research for understanding complex FFF techniques and/or pro cesses involving extruding polymer onto surfaces.

Material Extrusion additive manufacturing (MEX) represents the most widely implemented form of additive manufacturing due to its high performance-cost ratio and robustness. Being an extrusion process in its essence, this process enables the free form fabrication of a wide range of thermoplastic materials. However, in most typical MEX processes, only amorphous polymers are being used as feedstock material owing to their smaller dimensional shrinkage during cooling and well-stablished process/structure/property (P/S/P) relationship. Semi-crystalline polymers, with their crystalline nature, possess unique properties such as enhanced mechanical properties and improved chemical resistance. However, due to the inherent processing challenges in MEX of semi-crystalline polymers, the P/S/P relationships are much less established, thus limits the application of semi-crystalline polymers in MEX. The overall aim of this thesis is to advance the understanding of P/S/P relationship of semi-crystalline polymers in MEX. This is accomplished through both experimental and simulation-based research. With a typical commodity semi-crystalline polymer, Poly (ethylene terephthalate) (PET), selected as the benchmark material. First, we experimentally explored the MEX printing of both neat and glass fiber (GF) reinforced recycled PET (rPET). Excellent MEX printability were shown for both neat and composite materials, with GF reinforced parts showing a significant improved mechanical property. Notably, a gradient of crystallinity induced by a different toolpathing time was highlighted. In the second project, to further investigate the impact of MEX parameter on crystallinity and mechanical properties, a series of benchmark parts were printed with neat PET and analyzed. The effect of part design and MEX parameter on thermal history during printing was revealed though a comparative analysis of IR thermography. Subsequent Raman spectroscopy and mechanical test indicated that crystallinity developed during the MEX process can adversely affects the interlayer adhesion. In the third project, a 3D heat transfer model was developed to simulate and understand the thermal history of MEX feedstock material during printing, this model is then thoroughly validated against the experimental IR thermography data. While good prediction accuracy was shown for some scenarios, the research identified and discussed several unreported challenges that significantly affect the model's prediction performance in certain conditions. In the fourth project, we employed a non-isothermal crystallization model to directly predict the development of crystallinity based on given temperature profiles, whether monitored experimentally or predicted by the heat transfer model. The research documented notable discrepancies between the model's predictions and actual crystallinity measurements, and the potential source of the error was addressed. In summary, this thesis explored the MEX printing of semi-crystalline polymer and its fiber reinforced composite. The influence of MEX parameters and part designs on the printed part's thermal history, crystallinity and mechanical performance was then thoroughly investigated. A heat transfer model and a non-isothermal crystallization model were constructed and employed. With rigorous validation against experimental data, previously unreported challenges in MEX thermal and crystallization modeling was highlighted. Overall, this thesis deepens the understanding of current semi-crystalline polymer's P/S/P relationship in MEX, and offers insights for the optimization and future research in the field of both experiment and simulation of MEX. / Doctor of Philosophy / Material extrusion additive manufacturing (MEX), also known as fused filament fabrication (FFF), is a popular form of 3D printing known for its cost-effectiveness and versatility in creating objects from plastic materials. Traditionally, MEX utilizes amorphous polymers because they are less prone to shrinkage and thus easier to print. However, semi-crystalline polymers, offer enhanced strength and chemicals resistance, yet they pose significant challenges in printing due to a limited understanding of their process/structure/property (P/S/P) relationships in MEX. This research aims to improve our understanding of P/S/P relationships of semi-crystalline polymers in MEX. The study utilizes a typical semi-crystalline polymer, Poly (ethylene terephthalate) (PET), as the benchmark material. The study begins with the exploration of the MEX printing of recycled PET (rPET) and its glass fiber composite, finding that with appropriate MEX parameters, both feedstocks are highly printable, and the incorporation of glass fibers substantially increased the strength of the printed parts. Subsequently, a comprehensive investigation regarding the intricate relationship between crystallinity development, mechanical properties, and the MEX printing process is conducted. Our research revealed that the MEX process and the design of the part both considerably affect the crystallinity of the final part, thereby influencing its mechanical properties. In the third chapter, a 3D heat transfer model is constructed to better understand and predict the temperature evolution of materials during MEX printing. Most importantly, the modeling results are rigorously validated against experimental data, showing promising results. However, it also reveals challenges in precisely predicting the temperature of parts under certain conditions. The research then evaluates the applicability of Nakamura non-isothermal crystallization model for MEX printing scenarios. It is found that this model underestimates crystallinity in MEX, primarily because it does not account for shear-induced crystallization, a critical factor in the process. This finding underscores the necessity for more advanced models that can effectively capture the complex dynamics of MEX. In summary, this dissertation significantly enhances our understanding of the behavior of semi-crystalline polymers in MEX printing. It sheds light on the complex relationship between the printing process, the structure of the material, and the final properties of the printed object. This work not only advances our knowledge in 3D printing but also paves the way for more sophisticated modeling approaches, optimizing the MEX process and expanding its potential applications.

Additive manufacturing (AM) is a rapidly growing and evolving form of product development that has the potential to revolutionize both the industrial and academic spheres. For example, AM offers much greater freedom of design while producing significantly less waste than most traditional manufacturing techniques such as injection and blow molding. Filament-based material extrusion AM, commonly referred to as fused filament fabrication (FFF), is one of the most well-known AM modalities using a polymeric feedstock; however, several obstacles currently prohibit widespread use of this manufacturing technique to produce end-use products, which will be discussed in this dissertation. Specifically, a severely limited material catalog restricts tailored product development and the variety of applications. Additionally, poor interlayer adhesion results in anisotropic mechanical properties which can lead to failure, an issue not often observed in traditional manufacturing techniques. A review of the current state of the art research in the field of FFF, focusing on the multiphysics-based modeling of the system and exploring some empirically determined relationships, is presented herein to provide a more thorough understanding of FFF and its complexities. This review further guides the work discussed in this dissertation. The primary focus of this dissertation is to expand the fundamental understanding of the FFF process, which has proven difficult to measure directly. On this size scale, introduction of measurement devices such as thermocouples and pressure transducers can significantly alter the behavior of the process or require major changes to the geometry of the system, leading to spurious measurements, incorrect outcomes, and/or conclusions. Therefore, the research presented in this dissertation focuses on the development and validation of predictive models based on first principles approaches that can provide information leading to the optimization of printing parameters and exploration of novel and/or modified materials without an exhaustive and inefficient trial-and-error process. The first potential issue a novel material may experience in FFF is an inability to extrude from the heated nozzle. Prior to this work, no efforts were focused on the molten material inside the liquefier and its propensity to flow in the reverse direction through the annular region between the filament and the nozzle wall, referred to as annular backflow. The study presented in this dissertation explores this phenomenon, determining its cause and sensitivity to processing parameters and material properties. A dimensionless number, named the "Flow Identification Number" or FIN, is defined that can predict the propensity to backflow based on the material's shear thinning behavior, the filament diameter, the nozzle diameter, and the filament feed rate and subsequent pressure inside the nozzle. An analysis of the FIN suggested that the backflow potential of a given material is most sensitive to the filament diameter and its shear thinning behavior (power law index). The predictive model and FIN were explored using three materials with significantly different onsets of shear thinning. The experiments validated both the backflow model and a previously derived buckling model, leading to the development of a rapid screening technique to efficiently estimate the extrudability of a material in FFF. Following extrusion from the nozzle, the temperature profile of the deposited filament will determine nearly all of the mechanical properties of the printed part as well as the geometry of the individual roads and layers because of its temperature dependent viscoelastic behavior. Therefore, to better understand the influence of the temperature profile on the evolution of the road geometry and subsequent interlayer bonding, a three-dimensional finite element heat transfer analysis was developed. The focus of this study is the high use temperature engineering thermoplastic polymer polyetherimide, specifically Ultem™ 1010, which had not been studied in prior modeling analyses but presents significant challenges in terms of large thermal gradients and challenging AM machine requirements. Through this analysis, it was discovered that convective cooling dominated the heat transfer (on the desktop FFF scale) producing a significant cross-sectional temperature gradient, whereas the gradient along the axis was observed to be significantly smaller. However, these results highlighted a primary limitation in computer modeling based on computational time requirements. This study, utilizing a well-defined three-dimensional model based on a geometry measured empirically, produced results describing 0.5 s of printing time in the printing process and elucidated great details in the road shape and thermal profile, but required more than a week of computation time, suggesting a need for to modify the modeling approach while still accurately capturing the physics of the FFF layer deposition process. The determination of the extensive time required to converge the three-dimensional model, as well as the identification of a relative lack of axial thermal transfer, led to the development of a two-dimensional, cross-sectional heat transfer analysis based on a finite difference approach. This analysis was coupled with a diffusion model and a stress development model to estimate the recovery of the bulk strength and warping potential of a printed part, respectively. Through this analysis, it was determined that a deposited road may remain above Tg for 2-10 s, depending on the layer time, or time required for the nozzle to pass a specific point in the x-y plane between each layer. The predicted strength recovery was significantly overestimated, leading to the discovery of the extreme sensitivity of the predictive models to the relaxation time of a material, particularly at long layer times. When the deposited filament has enough time to attain an equilibrium temperature, small changes in the relaxation time of the material resulted in significant changes in the predicted healing results. These results highlight the need for exact estimations of the material parameters to accurately predict the properties of the final print. / Doctor of Philosophy / Additive manufacturing (AM), particularly filament-based material extrusion additive manufacturing, commonly known as fused filament fabrication (FFF), has recently become the subject of much study with the goal of utilizing it to produce parts tailored to specific purposes quickly and cheaply. AM is especially suited to this purpose due to its ability to produce highly complex parts with the ability to change design very easily. Furthermore, AM typically produces less waste than many traditional manufacturing techniques due to the process building a part layer by layer rather than removing unneeded material from a larger piece, resulting in a cheaper process. These freedoms make AM, and FFF in particular, highly prized among industrial producers. However, numerous challenges prevent the adoption of FFF by these companies. Particularly, a lack of available material options and anisotropic material properties lead to issues when attempting to produce a part targeted for use in a specific field. FFF is primarily commercially limited to two materials: polylactic acid (PLA) and acrylonitrile-butadiene-styrene (ABS) with a few other materials available in more specialized fields. However, essentially all these materials are limited to low use temperatures (less than 300 °C) and are primarily amorphous or with nearly negligible amounts of crystallinity. This severely limits the ability to tailor a printed part to a specific purpose and restricts the use of printed parts to applications requiring very low strengths. This is one reason why FFF, and most types of AM, is limited to the prototyping field rather than end-use applications. The other reason, anisotropic mechanical properties, is caused by the building methodology of AM. Creating a part layer by layer naturally introduces potential areas of weakness at the joining of the layers. If bulk properties are not recovered, the interlayer bond acts as a stress concentrator under load and will break before the bulk material. The work presented in this dissertation proposes methods to better understand the FFF system in order to address these two issues, leading to the optimization of the printing process and ability to expand the material catalog, particularly in the direction of high use temperature materials. The research discussed herein attempts to develop predictive models that may allow exploration into the FFF system which can be difficult to do experimentally, and by predicting the properties of a printed part, the models can guide future experimentation in FFF without the need for an extensive trial-and-error process. The work presented in this dissertation includes exploring the flow phenomena inside the FFF nozzle to determine extrudability as well as two-dimension and three-dimension heat transfer models with the goal of describing the viscoelastic, flow, diffusion, and stress development phenomena present in FFF.

This thesis is concerned with fused filament fabrication (FFF) of cellulose nanocrystal (CNC) and thermoplastic polyurethane (TPU) nanocomposites, focusing on preliminary optimization of a processing window for 3D printing of mechanically responsive composites and the influence of temperature on mechanical adaptivity, thermal stability, and rheology. CNC thermoplastic nanocomposites are a water responsive, mechanically adaptive material that has been gaining interest in additive manufacturing for 4D-printing applications. Using a desktop FlashForge Pro 3D printer, we first established a viable processing window for a nanocomposite comprising 10 wt% CNCs in a thermoplastic urethane (TPU) matrix, formed into a filament through the combination of masterbatch solvent casting and single screw extrusion. Printing temperatures of 240, 250, and 260°C and printing speeds of 600, 1100, and 1600 mm/min instituted a consistent 3D-printing process that produced characterizable CNC/TPU nanocomposite samples. To distinguish the effects of these parameters on the mechanical properties of the printed CNC/TPU samples, a design of experiments (DOE) with two factors and three levels was implemented for each combination of printing temperature and speed. Dynamic mechanical analysis (DMA) highlighted 43 and 66% increases in dry-state storage moduli values as printing speed increases for 250 and 260°C, respectively. 64 and 23% increases in dry-state storage moduli were also observed for 600 and 1100 mm/min, respectively, as temperature decreased from 260 to 250°C. For samples printed at 240°C and 1600 mm/min, it was determined that that parameter set may have fallen out of the processing window due to inconsistent deposition and lower dry-state storage moduli than what the slower speeds exhibited. As a result, the samples printed at 240°C did not follow the same trends as 250 and 260°C. Further analysis helped determine that the thermal energy experienced at the higher end printing temperatures coupled with the slower speeds decreased the dry-state storage moduli by nearly 50% and lead to darker colored samples, suggesting CNC degradation. Isothermal thermogravimetric analyses (TGA) demonstrated that the CNC/TPU filament would degrade at relative residence times in the nozzle for all the chosen printing temperatures. However, degradation did not eliminate the samples' ability to mechanically adapt to a moisture-rich environment. DMA results verified that mechanical adaptivity was persistent for all temperature and speed combinations as samples were immersed in water. However, for the higher temperatures and slower speeds, there was about a 15% decrease in adaptability. Optimal parameters of 250°C and 1600 mm/min provided the highest dry-state storage modulus of 49.7 +/- 0.5 MPa and the highest degree of mechanical adaptivity of 51.9%. To establish the CNC/TPU nanocomposite's use in 4D printing applications, shape memory analysis was conducted on a sample printed at the optimal parameters. Multiple wetting, straining, and drying steps were conducted to highlight 76% and 42% values for shape fixity and shape recovery, respectively. Furthermore, a foldable box was printed to serve as an example of a self-deployable structure application. The box displayed shape fixity and recovery values of 67% and 26%, respectively, further illustrating significant promise and progress for CNC/TPU nanocomposites in 4D-printed, shape adaptable structures. Further analysis of the effect of degradation during FFF of the CNC/TPU nanocomposite was conducted using rotational rheometry, Fourier-Transform Infrared Spectroscopy (FTIR), and polymer swelling experiments. A temperature ramp from 180 to 270°C showed a significant increase in complex viscosity (h*) at the chosen printing temperatures (240, 250, and 260°C). Moreover, h* of neat TPU suddenly increases at 230°C, indicating a potential chemical crosslinking reaction taking place. 20-minute time sweeps further verified that h* increases along with steady increases in storage (G') and loss (G'') moduli. From these results, it was hypothesized that crosslinking is occurring between CNCs and TPU. Preliminary characterization with FTIR was used to probe the molecular structure of thermally crosslinked samples. At 1060 and 1703 cm-1, there are significant differences in intensities (molecular vibrations) as the temperature increases from 180 to 260°C related to primary alcohol formation and hydrogen bonded carbonyl groups, respectively. The hypothesis is the disassociation of TPU carbamate bonds into soft segments with primary alcohols and hard segments with isocyanate groups. The subsequent increasing peaks at 1060 and 1703 cm-1 may indicate crosslinking of CNCs with these disassociated TPU segments. To quantify potential crosslinking, polymer swelling experiments were implemented. After being submerged in dimethylformamide (DMF) for 24 hours, CNC/TPU samples thermally aged for 15 minutes at 240, 250, and 260°C retained their filament shape and did not dissolve. The 240 and 250°C aged samples had relatively similar crosslink densities close to 900 mole/cm3. However, from 250 to 260°C, there was about a 36% increase in crosslink density. These results suggest that crosslinking is occurring at these printing temperatures because both CNCs and TPU are thermally degrading into reactive components that will lead to covalent crosslinks degradation. Additional characterization is needed to further verify the chemical structure of these CNC/TPU nanocomposites which would provide significant insight for CNC/TPU processing and 3D printing into tunable printed parts with varying degrees of crosslinking. / Master of Science / This thesis is concerned with the development of a processing window for mechanically adaptive cellulose nanocrystal (CNC) and thermoplastic polyurethane (TPU) nanocomposites with fused filament fabrication (FFF) and, evaluating the influence of elevated temperatures on the mechanical, thermal, and rheological properties of said nanocomposite. CNC thermoplastic nanocomposites are a water responsive, mechanically adaptive material that has been gaining interest in additive manufacturing for 4D-printing. Using a desktop 3D-printer, an initial processing window for a 10 wt% CNC in TPU was established with printing temperatures of 240, 250, and 260°C and printing speeds of 600, 1100, and 1600 mm/min. A design of experiments (DOE) was implemented to determine the effects of these parameters on the mechanical properties and mechanical adaptability of printed CNC/TPU parts. Dynamic mechanical analysis (DMA) suggests that combinations of higher temperatures and lower speeds result in reduced storage moduli values for printed CNC/TPU parts. However, mechanical adaptation, or the ability to soften upon water exposure, persists for all the printed samples. Additionally, there was significant discolorations of the printed samples at the higher temperature and slower speed combinations, suggesting thermal degradation is occurring during the printing process. The decrease in storage moduli and discoloration is attributed to thermal energy input, as thermogravimetric analysis indicated thermal degradation was indeed occurring during the printing process regardless of printing temperature. Using the parameters (250°C and 1600 mm/min) that displayed the superior mechanical properties, as well as mechanical adaptivity, shape memory analysis was conducted. The optimal printed part was able to hold 76% of the shape it was strained to, while recovering 42% of the original unstrained shape once immersed in water, indicating potential for shape memory and 4D-printing applications. Furthermore, a foldable box was printed with the optimal parameters and it displayed similar shape memory behavior, illustrating promise for CNC/TPU self-deployable shape adaptable structures. To further study the effect of degradation on the CNC/TPU system, melt flow properties, molecular structure, and polymer swelling were investigated. At the printing temperatures (240, 250, and 260°C), the complex viscosity of the CNC/TPU filament experienced an exponential increase, indicating potential network formation between the CNCs and TPU. Fourier-Transform Infrared Spectroscopy (FTIR) highlighted changes in the molecular structure for the CNC/TPU filament as temperature increased from 240 to 260°C, which suggests that chemical structure changes are occurring because of degradation. The hypothesis is TPU is disassociated into free soft and hard segments that the CNCs can covalently crosslink with, which can potentially be explained by the increases in the FTIR intensities relating to TPU and CNC's chemical structure. To further quantify potential crosslinking between CNCs and TPU, polymer swelling experiments were implemented. The results from these experiments suggest that increasing printing temperatures from 240 to 260°C will lead to higher degrees of crosslinking. Further investigation could yield the validity of this crosslinking and additional optimization of FFF printing with CNC/TPU nanocomposites.

One of the major limitations in Fused Filament Fabrication (FFF), a form of additive manufacturing, is the lack of composites with superior mechanical properties. Traditionally, carbon and glass fibers are widely used to improve the physical properties of polymeric matrices. However, the blending methods lead to fiber breakage, preventing generation of long fiber reinforced filaments essential for printing load-bearing components. Our approach to improve tensile properties of the printed parts was to use in-situ composites to avoid fiber breakage during filament generation. In the filaments generated, we used thermotropic liquid crystalline polymers (TLCPs) to reinforce acrylonitrile butadiene styrene (ABS) and a high performance thermoplastic, polyphenylene sulfide (PPS). The TLCPs are composed of rod-like monomers which are highly aligned under extensional kinematics imparting excellent one-dimensional tensile properties. The tensile strength and modulus of the 40 wt.% TLCP/ABS filaments was improved by 7 and 20 times, respectively. On the other hand, the 67 wt.% TLCP/PPS filament tensile strength and modulus were improved by 2 and 12 times, respectively. The filaments were generated using dual extrusion technology to produce nearly continuously reinforced filaments and to avoid matrix degradation. Rheological tests were taken advantage of to determine the processing conditions. Dual extrusion technology allowed plasticating the matrix and the reinforcing polymer separately in different extruders. Then continuous streams of TLCP were injected below the TLCP melting temperature into the matrix polymer to avoid matrix degradation. The blend was then passed through a series of static mixers, subdividing the layers into finer streams, eventually leading to nearly continuous fibrils which were an order of magnitude lower in diameter than those of the carbon and glass fibers. The composite filaments were printed below the melting temperature of the TLCPs, and the conditions were determined to avoid the relaxation of the order in the TLCPs. On printing, a matrix-like printing performance was obtained, such that the printer was able to take sharp turns in comparison with the traditionally used fibers. Moreover, the filaments led to a significant improvement in the tensile properties on using in FFF and other conventional technologies such as injection and compression molding. / Doctor of Philosophy / In this work two thermoplastic matrices, acrylonitrile butadiene styrene (ABS) and polyphenylene sulfide (PPS), were reinforced with higher melting thermoplastics of superior properties called thermotropic liquid crystalline polymers (TLCPs). This was done so that the resulting filaments could be 3D-printed without melting the TLCPs. The goal of this work was to generate nearly continuous reinforcement in the filaments and to avoid matrix degradation, and, hence, a technology called dual extrusion technology was used for the filament generation. The temperatures required for filament generation were determined using rheology, which involves the study of flow behavior of complex fluids. Dual extrusion technology allows processing of the constituent polymers separately at different temperatures, followed by a continuous injection of multiple TLCP-streams into the matrix polymers. In addition, the use of static mixers (metallic components kept in the path of flow to striate incoming streams) leads to further divisions of the TLCP-streams which are eventually drawn by pulling to orient the TLCP phase. The resulting filaments exhibited specific properties (normalized tensile properties) higher than aluminum and contained fibers that were nearly continuous, highly oriented, and an order in magnitude lower in diameter than those of carbon and glass fiber, which are commonly used reinforcements. High alignment and lower fiber diameter are essential for printing smoother printed parts. The filaments were intended to be printed without melting the TLCPs. However, previous studies involving the use of TLCP reinforced composites in conventional technologies have reported the occurrence of orientation relaxation on postprocessing, which decreases their tensile v properties. Therefore, temperatures required for 3D printing were determined using compression molding to retain filament properties on printing to the maximum extent. On printing using an unmodified 3D printer, parts were printed by taking 180º turns during material deposition. Contrarily, the use of continuous carbon fibers required a modified 3D printer to allow impregnation during 3D printing. Moreover, the performance comparison showed that the continuous carbon fibers could not be deposited in tighter loops. The properties of the printed parts were higher than those obtained on using short fibers and approaching those of the continuous fiber composites.

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.

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