Published Article / Current fused deposition modelling (FDM) technologies deposit material as flat layers. The result is a "stair-case" effect on non-vertical or horizontal surfaces, and compromised part strength because of weakness between the laminations. This paper describes an FDM method through which layers of build material are deposited as curved layers following the shape of the part, thus removing the stair-case effect and creating parts that have an even strength distribution over their entire surface. Support material is first deposited as conventional flat layers, and build material is then deposited over the support structure following the curves of the part. The paper discusses a proof of concept of the system, the algorithms used to generate the curve paths for the deposition head, and examines the challenges and possibilities of this technology, including the capability of including composite materials.

Fused Deposition Modelling (FDM) is one of the most widely used Rapid Prototyping processes that uses the technique of depositing a semi-solid material in layers to build up a part and finds application in a variety of situations, be it making a mould for the rapid production of an industrial tool or the production of models for preoperative planning of complex cranial reconstructive surgery. When it comes to directly producing the end products, the process is still in its infancy, using inferior materials and flat layer deposition, bringing forth shortcomings such as poor surface quality, low strength for curved parts, and undesirably higher number of layers. Some of these shortcomings can be overcome if material deposition is modelled in curved layers as against the traditional flat-layer slicing and deposition. While the stair case effect can be significantly minimized, mechanical properties of the parts will also be enhanced due to continuity in fibres and the elimination of the inherent weakness between laminations. However, this being a fairly new idea, there are no existing facilities for practically implementing and experimentally testing this concept of Curved Layered Fused Deposition Modeling (CLFDM). The current research is to develop both hardware and software systems to build a working FDM system and implement CLFDM. The project involves the construction of an FDM system and then development of mathematical models for curved slicing. The numerical data generated from curved slicing algorithms is integrated with the hardware system for the practical implementation of CLFDM. Efficient curved slicing algorithms are developed and successfully used on the FDM system built for the practical implementation of CLFDM. Several case studies involving geometrical complications of increasing complexities have been successfully modelled and physically produced using CLFDM.

Fused Deposition Modelling (FDM) is one of the most widely used Rapid Prototyping processes that uses the technique of depositing a semi-solid material in layers to build up a part and finds application in a variety of situations, be it making a mould for the rapid production of an industrial tool or the production of models for preoperative planning of complex cranial reconstructive surgery. When it comes to directly producing the end products, the process is still in its infancy, using inferior materials and flat layer deposition, bringing forth shortcomings such as poor surface quality, low strength for curved parts, and undesirably higher number of layers. Some of these shortcomings can be overcome if material deposition is modelled in curved layers as against the traditional flat-layer slicing and deposition. While the stair case effect can be significantly minimized, mechanical properties of the parts will also be enhanced due to continuity in fibres and the elimination of the inherent weakness between laminations. However, this being a fairly new idea, there are no existing facilities for practically implementing and experimentally testing this concept of Curved Layered Fused Deposition Modeling (CLFDM). The current research is to develop both hardware and software systems to build a working FDM system and implement CLFDM. The project involves the construction of an FDM system and then development of mathematical models for curved slicing. The numerical data generated from curved slicing algorithms is integrated with the hardware system for the practical implementation of CLFDM. Efficient curved slicing algorithms are developed and successfully used on the FDM system built for the practical implementation of CLFDM. Several case studies involving geometrical complications of increasing complexities have been successfully modelled and physically produced using CLFDM.

Supercapacitors, also known as electrochemical capacitors, have shown great potential as energy storage devices; and 3D printing likewise as a manufacturing technique. This research progressively investigates combining these two technologies to fabricate 3D-printed, electrochemical double-layer capacitors (EDLCs). Small EDLCs were designed in a sandwich structure with an FDM-printed plastic frame and carbon electrodes. Inkjet printing was initially combined with FDM printing to produce a pilot sample with a silver ink current collector, however this performed poorly (Cs = 6 mF/g). Henceforth a paste extrusion system was added to the FDM printer to deposit the current collectors and electrodes, fabricating the entire device in a single continuous process. This process was progressively developed and tested, ultimately attaining specific capacitances of 200 mF/g. The fully integrated 3D printing process used to manufacture the EDLCs was a novel approach. Combining the FDM printer with a paste extruder allowed for a high degree of dimensional accuracy, as well as simplifying the production process. This aspect of the design functioned successfully, without significant faults, and proved a reliable fabrication method. The later designs used in this study provided the EDLCs extendable by incorporating connection jacks. This was to create the possibility to increase capacitance simply by connecting multiple EDLCs together. Tests of this feature showed that it worked well, with the extendable EDLCs delivering outputs very close to the theoretical maximum efficiency of the unit. Carbon conductive paint was applied as a current collector and electrode for the 3D printed EDLCs in an exploration of metal-free 3D printed supercapacitors. These metal-free EDLCs were found to provide around 60% of the specific capacitance of the best performing EDLC variant produced (silver paint current collectors with activated carbon and carbon paint mixture electrodes). Although considerable improvement is required to produce EDLC samples with comparable capacitances to existing commercial manufacturing techniques, this study lays important groundwork in this area, and has introduces effective and innovative design ideas for supercapacitors and integrated 3D printing processes.

Traditionally, the mechanical testing of ankle-foot orthoses (AFOs) has been performed with simple limb surrogates, typically with a single axis ankle joint and rigid foot and shank components. Since many current AFO designs allow 3D motion, a surrogate lower limb (SLL) that provides anatomically similar motion in all planes is needed to enable realistic load testing and cyclic testing in a controlled manner. The aim of this thesis was to design, fabricate and test a novel SLL that provides anatomically realistic 3D foot motion, based on a consensus of the passive lower limb range of motion (RoM) found in the literature. The SLL design was inspired by the Rizzoli model, sectioning the lower limb into five segments (shank, hindfoot, midfoot, forefoot, toes). Ball and socket joints were used for the shank-hindfoot, hindfoot-midfoot, and midfoot-forefoot. Forefoot-toes used a hinge-type joint. 3D printed flexible thermoplastic polyurethane (TPU) snap-fit connectors connected the 3D printed nylon foot blocks. A threaded ball stud connected the shank shaft and hindfoot. This shank shaft was surrounded by a 3D printed polylactic acid (PLA) shank cover. The foot was cast in silicone rubber to emulate soft tissue, with a PLA custom mould based on a Össur prosthetic foot cover model. The SLL was successfully designed for easy fabrication using readily available techniques, materials, and components. Only the metal shaft required additional machining. 3D printed components used an affordable 3D printer (Artillery Sidewinder X1), and readily available nylon, PLA, and TPU. Using motion capture testing, SLL foot rotation angles were found to be within standard deviation of mean foot passive rotation angle ranges found in the literature, showing that most joints were within 5° of target maximum rotation angles. With load testing, the SLL was shown to survive static loads representing 1.5 times body weight for a 100 kg individuals and cyclic loads representing normal gait loading for 500,000 cycles.

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This thesis aims to investigate the use of additive manufacturing (AM) as a novel manufacturing process for the production of milli-scale chemical reaction systems. Five well developed additive manufacturing techniques; stereolithography (SL), selective laser melting (SLM), fused deposition modelling (FDM), ultrasonic additive manufacture (UAM) and selective laser sintering (SLS) were used to manufacture a number of miniaturised flow devices which were tested using a range of organic and inorganic reactions. SL was used to manufacture a range of functioning milli-scale flow devices from Accura 60 photoresin, with both simple and complex internal channel networks. These devices were used to perform a range of organic and inorganic reactions, including aldehyde and ketone functional group interconversions. Conversion of products within these reactors, were shown to be comparable to commercially available milli-scale coil reactors. More complex designs, which allowed SL parts to be integrated to existing flow and analytical instrumentation, allowed us to develop an automated reaction analysis and optimisation platform. This platform allowed precise control over the reaction conditions, including flow rate, temperature and reagent composition. We also designed a simplex type reaction optimisation software package that could input data in the form of reaction conversions, peak intensities, and thermocouple data, and generate a new set of optimal reaction conditions. SL parts which incorporated embedded analytical components were also manufactured, which allowed us to perform inline reaction analysis as a feedback method for input into the optimisation platform. Stereolithography was shown to be a highly versatile manufacturing method for designing and producing these flow devices, however the process was shown to be still limited by the range of processable materials currently commercially available. SLM was also used to manufacture a number of functioning milli-scale flow devices from stainless steel and titanium, which had simplistic internal channel designs of diameters ranging from 1 to 3 mm. Again, SLM parts were manufactured which incorporated embedded analytical components, which could be integrated into an automated reaction platform. These devices, unlike parts produced via SL, could be attached to heating platforms to allow us to perform high temperature reactions. This control over the reaction temperature formed an essential part of the reaction optimisation platform. These parts were again used to perform a ketone functional group interconversion. Internal structures of these SLM parts were also visualised via micro computed tomography (μCT or microCT) scanning as well as optical microscopy. FDM was used throughout the project as an inexpensive method of prototyping parts which were to be manufactured via more expensive manufacturing processes. This prototyping allowed the optimisation of intricate design features, such as the manufacture of an inline spectroscopic flow cell for integration with a commercially available LC system. FDM was also proposed as a customisable approach to designing and manufacturing flow devices with embedded components, however the current limitations in build resolution and materials choices severely limited the use of FDM for this application. UAM was also proposed as a novel manufacturing process whereby the build process would allow discrete components to be embedded directly into a flow channel. This was demonstrated by embedding a type-k thermocouple across a 2 mm channel. The data from this thermocouple was monitored during a heated reaction, and used as a method of determining the exact reaction conditions the reaction medium was being exposed to. SLS was also proposed as a possible manufacturing method for milli-scale flow devices, however it proved difficult to remove un-sintered powder from parts with internal channel diameters as high as 5 mm. It was shown that this powder was forming a dense semi solid, due to the large degree of shrinkage upon cooling of the SLS parts, which was compressing the powder. More research into optimum processing conditions is required before SLS could be used for the production of intricate channel networks.

This thesis presents a multiscale investigation and characterization of additive manufactured Polyamide material using fused deposition modelling technique. Manufacturing was performed using Markforgeds – Mark one 3D printer.  A multiscale investigation dedicated to minimizing the effect of shape distortion during 3D printing are presented, focusing on both molecular alignment in microstructure and implementing internal structures in mesostructure. Characterization on samples investigating microstructure was performed with coefficient of linear thermal expansion measurement and 3-point bending experiment. Different samples with varying infill patterns are tested and results indicates an isotropic behaviour through the manufactured samples and implies no molecular alignment due to printing pattern. In meso-structure, an implemented internal pattern is investigated. All samples are measured with 3D scanning equipment to localize and measure the magnitude of shape distortion. Attempts to find relationships in shape distortion and porosity between the samples resulted in no observed trends. Compressive experiments where performed on samples in axial- and transverse directions resulting in anisotropic behaviour. The largest compressive stiffness is recorded in axial direction reaching 0,33 GPa. The study is done in collaboration with Swerea SICOMP and Luleå University of Technology.

Shortening of the time required to make first product after demand is a crucial factor in every field of industry, not excluding the foundry. To lower this delay, there are rapid prototyping methods. The aim of this thesis is to execute an experiment and then evaluate possibilities of using patterns made by 3D FDM printer on an automatic molding line.