Additive Manufacturing (AM) provides a unique opportunity for fabrication of personalized medicine, where each oral dosage could be tailored to satisfy specific needs of each individual patient. Binder jetting, an easily scalable AM technique that is capable of processing the powdered raw material used by tablet manufacturers, is an attractive means for producing individualized pharmaceutical tablets. However, due to the low density of the printed specimens and incompatible binder-powder combination, tablets fabricated by this AM technology suffer from poor strength. The research is introducing an additional composition in the binder jetting powder bed (e.g., powdered sugar) could significantly enhance the compressive strength of the as-fabricated tablets, as compared with those tablets fabricated without the additional powder binding agent. However, no previous research demonstrated comprehensive approaches to enhance the poor performance of the 3D printed tablets. Therefore, the goal of this work is to identify processing techniques for improving the strength of binder jetted tablets, including the use of (i) novel jettable polymeric binders (e.g., 4-arm star polyvinylpyrrolidone (PVP), DI water, and different i) weight percentage of sorbitol binder) and (ii) introducing an additional powder binding agent into the powder bed (e.g.., different wt% of powdered sugar). / M.S. / Three-dimensional printing is well-known as 3D printing. 3D printing pills are printed from the 3D printer. As of today, we now stand on the brink of a fourth industrial revolution. By the remarkable technological advancements of the twenty-first century, manufacturing is now becoming digitized. Instead of using a large batch process as traditional, customized printlets with a tailored dose, shape, size, and release characteristics could be produced on- demand. The goal of developing pharmaceutical printing is to reduce the cost of labor, shorten the time of manufacturing, and tailor the pills for patients. And have the potential to cause a paradigm shift in medicine design, manufacture, and use. This paper aims to discuss the current and future potential applications of 3D printing in healthcare and, ultimately, the power of 3D printing in pharmaceuticals.

3D-skrivare är en allt vanligare syn i dagens samhälle. De flesta 3D-skrivarna skriver ut i plast men andra tekniker har också utvecklats, däribland Binder Jetting som är en teknik som används vid utskrifter i pulver. I detta arbete har en skrivare som tillämpar Binder Jetting-teknik byggts. Projektets mål är att kunna skriva ut enklare 3D-modeller. Arbetet bestod av att skruva ihop skrivarens alla delar i metall och plast, tillverka kretskort, koppla elektronik samt ladda över programvara till skrivaren. De kretskort som egentillverkades är specialdesignade för just denna modell. Det ena har som funktion att förstärka spänningen från 12V till 20V samt öka antalet utgångar från Megatronics-kortet. Det andra har som funktion att konvertera en kontakt från en utgång till en annan. Då skrivaren byggts ihop testades den genom att göra en utskrift i 2D. Vid testkörningen i 2D framkom det att bläckpatronen inte skrev ut något bläck. För att lösa problemet påbörjades en felsökning. Det som undersöktes var bläckpatronen, kablar och de egengjorda kretskorten. Under felsökningens gång upptäcktes en kabel som glappade samt två feldragna ledningar på ett av kretskorten. Efter att båda dessa problem blivit åtgärdade kunde skrivaren göra en utskrift i 2D. Nästa steg var att fylla skrivaren med pulver för att testa att skriva ut en 3D-modell i form av en kub. Resultatet blev bläckfärgat pulver då bläcket inte höll ihop gipset. Under slutet av utskriften blev utskriften även skev, det vill säga att varje lager försköts något, så de hamnade inte på varandra. Det kan bero på att stegmotorerna tappar kraft eller att något är fel med filen på SD-kortet som skrivaren hämtar information från. En vidareutveckling av skrivaren är att koppla upp den till wifi för att kunna skicka filer direkt till skrivaren utan att ha ett SD-kort som mellanhand. Ett långsiktigt mål är att utveckla skrivaren så att det kan skriva ut individanpassade läkemedel.

Binder jetting is an additive manufacturing process in which a part is fabricated layer-by-layer using inkjet technology to selectively dispense binder into powder layers in a designated area. The approach gives this process significant advantages over other additive manufacturing processes such as lower cost, capability to print in a wide range of materials, and little to no heat applied. Although binder jetting has many advantages and has been successful implemented in various industries its overall rate of adoption is slow compared to other processes. This is largely due to poor mechanical properties and consistency in printing which stems from a poor understanding of the interaction between the binder droplets and the powder bed. This is evident as print parameters for new machines and new materials are primarily determined by trial and error. The purpose of this thesis is to report the impact of various inkjet print parameters and humidity on the printing process in binder jetting. The binder/powder interaction is complex and highly dynamic where picoliter-sized droplets impact the powder bed at velocities of 1-10 m/s. Current methods of predicting this interaction assume that it is based only on binder and powder properties. This work studies the impact of inkjet printing parameters that are often overlooked with these assumptions. The impact of droplet velocity, droplet spacing, and droplet inter-arrival time was evaluated based on single line formation and effective saturation levels when printed into various powder material and sizes. Higher droplet velocities were found to decrease effective saturation with larger droplets (92-212 pl). However, droplet velocity had a negligible impact on saturation when printing with smaller droplets from 30 m orifice (29-65 pl). Line formation was dependent on both droplet inter-arrival time and droplet spacing. Max droplet spacing correlated to the square root of inter-arrival time. These results can guide selection of printing parameters that maximize build rates and reduce defects in printed parts. As the binder/powder interaction is difficult to observe and often line formation has been used as a method of observation. However, no report relating line formation to full layer parts exists. Optimal parameters determined in line printing are used for full feature parts. In addition, the impact of ambient humidity on the printing process is studied. The direct use of parameters optimized for line printing in printing a part was shown to be ineffective. When droplet spacing, line spacing, and layer thicknesses are comparable, single and multiple layers can be formed. Over short exposure periods of powder to ambient humidity produces negligible difference however, extended exposure periods significantly reduce the saturation and increase part size. Surface roughness is identified as a possible source of printing defects. Surface roughness increases significantly when printing the first layer but decreases with successive layers. This demonstrates a strong interaction between layers. The surface roughness and effective saturation was insensitive to line and droplet spacing below 60 m. Steam powder conditioning reduces sensitivity of both surface roughness and saturation to printing parameters but causes bleeding beyond the part boundaries. Further research should include improved methods of predicting ideal printing parameters and connecting it based on geometry and parts size. Further research is needed to confirm impact of surface roughness on defects in binder jetting parts. Development of methods to control spread of binder in premoistened powder to take advantage of its potential.

Binder jetting is an additive manufacturing process that layer by layer builds a 3D model by selectively binding regions of powder using binder deposited though an inkjet printhead. The process offers several advantages over other additive manufacturing processes including fast build rates, vast material selection, decreased cost, and part resolution. The main disadvantage of binder jetting is poor mechanical properties, stemming from a poor understanding of the process physics. Porosity in final parts is not uncommon, but there is little understanding of where the porosity originates. The purpose of this thesis is to report the investigation of increased powder bed cohesion and its effects on part formation, part properties, and printing parameters in binder jetting. The interaction between binder and powder is complex. Binder exiting the printhead impacts the powder bed at speeds up to 10 m/s. The kinetic energy carried by the droplet disperses into the powder bed on impact, causing some powder particles to eject from the bed and other particles to rearrange within the bed. The particle ejection and rearrangement is theorized to be the physical cause of porous regions in binder jetted parts. This work uses a method called pre-wetting to introduce small amounts of moisture into the powder bed to effectively increase the cohesive forces between powder particles. Increased cohesion makes particle ejection and rearrangement during the powder/binder interaction more difficult. A method of accomplishing pre-wetting was developed and achieved successful moisture delivery using water and a water/tri-ethylene glycol mixture. Printed lines were used to characterize moisture content and study its effects on line formation and saturation levels. Low levels of moisture were shown to perform the best. Particle ejection and rearrangement was shown to decrease with moisture addition. Pre-wetting was shown to eliminate the defect known as balling, increasing the parameters known to successfully print lines. Water was identified as a poor substance for pre-wetting due to rapid evaporation, but tri-ethylene glycol/water solutions succeeded in proper moisture delivery. Saturation levels in lines decrease with added moisture and part dimensions increase. high-speed x-ray imaging verified pre-wetting reduction in particle ejection and rearrangement as well as supply some preliminary understanding of void formation during the printing process. The first few layers of the binder jetting process have been shown to increase in surface roughness values when compared to the undisturbed powder bed. This is likely due to a balling-like effect seen in layers. The effects of pre-wetting on layer and multi-layer formation were studied. Pre-wetting reduced the surface roughness levels in printed layers to the levels near the levels seen in undisturbed powder beds. In contrast, saturation levels in layers and multi-layers increased in value above those found in parts printed into dry powder, giving indication that porous regions within bound parts are being eliminated. Layer and multi-layer parts showed increased part dimensions with the addition of moisture. Overall, pre-wetting was shown to greatly reduce the effects of the binder/powder interaction and results strongly suggest that pre-wetting mitigates defect creation during the printing process. Further research should include testing of thicker multi-layer parts to study how saturation trends continue with increased layer numbers. In-process drying should be used in conjunction with pre-wetting in multi-layer parts to determine its effects on saturation levels and part dimensions. Post processing should be done to partially sinter, or infiltrate multi-layer parts created with and without pre-wetting to analyze porosity.

Binder jet additive manufacturing (BJ) offers unique advantages, including the ability to produce complex geometries and utilize a wide range of materials, but faces challenges related to part quality and defect formation. This thesis investigates the effects of process parameters on droplet-powder interaction, powder relocation, and line formation in BJ printing. A custom BJ test platform was developed to enable precise control over key process parameters and in-situ monitoring. High-speed synchrotron X-ray imaging revealed modes of powder relocation above and below the powder bed surface. Testing revealed that parameters that increase moisture in the powder bed, such as lower droplet spacings, printing adjacent to previously printed geometry, and pre-wetting, reduce powder disturbance. Powder ejection above the powder bed surface was found to be affected by powder material, density, pre-wetting, previously printed geometry, and droplet spacing. Powder relocation below the powder bed surface was found to be largely independent of binder infiltration behavior, suggesting that powder relocation below the powder bed surface is driven by the kinetic impact of the droplet. A novel approach for analyzing printed lines demonstrated the sensitivity of line formation to various parameters, including droplet spacing, inter-arrival time, volume, and velocity. Lines were found to ball more readily at lower droplet spacings when printing at lower droplet velocities, although other coupled droplet parameters such as droplet volume and formation of satellite droplets also play a role. In printing conditions susceptible to balling, the droplets at the beginning of printed lines were observed to agglomerate, relocating powder and introducing error to the starting position of the line. Pre-wetting the powder bed with a water/TEG mixture significantly reduced balling and increased the range of droplet spacings and inter-arrival times resulting in successful line formation. Printing with low droplet velocities on moisture treated powder beds further increased the range of inter-arrival times that successfully formed lines. Reducing the kinetic energy of droplet impact by reducing droplet velocity and reducing the impact of balling by pre-wetting presents a set of process print process parameters that show promise to reduce powder relocation during the printing process. These findings provide valuable insights into the fundamental mechanisms of droplet-powder interaction, modes of powder relocation during printing that may contribute to porosity defects seen in final parts, and print process parameters that mitigate powder relocation due to droplet-powder interaction.

There is a link between the thermal and electrical properties of metal. The equation which links these two properties is called the Wiedemann-Franz Law. Also there is an emerging technology within Additive Manufacturing called Binder Jet Printing which can print high purity copper without heat stress within the material. Due to the Binder Jet Printings ability to print high resolution prints without any print through, this makes future use of this technology a necessity for future electrical and thermal components within computers . However a thermal and electrical conductivity analysis of binder jetted copper has never been performed, and needs to be for simulation with this material. Therefore within this thesis the relationship of the thermal and electrical properties of printed binder jetted copper part will be researched. To find the electrical resistivity of binder jetted copper, three sets of 2mm diameter rods where printed and then placed within a modified four wire resistance method test. For the thermal conductivity measurements a laser flash diffusivity machine was used, and three sets of 11 copper disks of approximately 1cm diameter by 1mm where printed. The data shows a strong linear trend linking electrical resistivity to the density ratio of the copper. Within the thermal conductance measurement, a lot more variability was seen within the three different prints. The 70% density ratio prints saw a large 13% spread in density ratios throughout the prints, which is believed to be caused by improper sintering due to temperature gradients near the door of the kiln. The 82% density prints saw better grouping of density ratios by placing the specimens in the back of the kiln. Lastly, the 92% prints saw the best density ratio grouping but the largest thermal conductivity variance. Even though the scatter plot for the thermal conductivity measurements are not as precise as the electrical resistivity measurements, it still shows a linear trend which matches the NASA data from 1971. Overall, these linear trends can be modeled and compiled into a new form of the Wiedemann-Franz law, which accounts for the density ratio of the binder jetted print. / Master of Science

This work created a manufacturing process and material system based on binder jetting Additive Manufacturing to process pure copper. In order to reduce the sintered part porosity and shape distortion during sintering, the powder bed voids were filled with smaller particles to improve the powder packing density. Through the investigation of a bimodal particle size powder bed and nanoparticle binders, this work aims to develop an understanding of (i) the relationship between printed part properties and powder bed particle size distribution, and (ii) the binder-powder interaction and printed primitive formation in binder jetting of metals. Bimodal powder mixtures created by mixing a coarse powder with a finer powder were investigated. Compared to the parts printed with the monosized fine powder constituent, the use of a bimodal powder mixture improved the powder flowability and packing density, and therefore increased the green part density (8.2%), reduced the sintering shrinkage (6.4%), and increased the sintered density (4.0%). The deposition of nanoparticles to the powder bed voids was achieved by three different metal binders: (i) a nanoparticles suspension in an existing organic binder, (ii) an inorganic nanosuspension, and (iii) a Metal-Organic-Decomposition ink. The use of nanoparticle binders improved the green part density and reduced the sintering shrinkage, which has led to an improved sintered density when high binder saturation ratios were used. A new binding mechanism based on sintering the jetted metal nanoparticles was demonstrated to be capable of (i) providing a permanent bonding for powders to improve the printed part structural integrity, and (ii) eliminating the need for organic adhesives to improve the printed part purity. Finally, the binder-powder interaction was studied by an experimental approach based on sessile drop goniometry on a powder bed. The dynamic contact angle of binder wetting capillary pores was calculated based on the binder penetration time, and used to describe the powder permeability and understand the binder penetration depth. This gained understanding was then used to study how the nanoparticle solid loading in a binder affect the binder-powder interactions and the printed primitive size, which provided an understanding for determining material compatibility and printing parameters in binder jetting. / PHD / The binder jetting Additive Manufacturing (AM) process can be used to fabricate net-shape metal parts with complex geometries by selectively inkjet printing a liquid binding agent into a powder bed, followed by post-process sintering of the printed green parts. Motivated by the need to create highly efficient thermal management systems, this work has established a binder jetting manufacturing process chain for fabricating components made of pure copper, a conductive and optically reflective material that is challenging to be processed by laser-based AM systems. In order to improve the performance metrics (e.g., mechanical strength, electrical and thermal conductivity) of the printed copper parts, an overall strategy to improve powder bed packing density by filling the powder bed voids with fine particles was investigated. Through the use of a bimodal powder mixture and a nanoparticle binder, the sintered density and structural integrity of the printed parts were improved. Via the investigation of these novel material systems created for binder jetting of copper, (i) the gaps in understanding the relationship between printed part properties and powder bed particle size distribution were filled, and (ii) an experimental approach to characterize and understand the binder-powder interaction and printed primitive formation was created to guide the selection of printing parameters in binder jetting.

Copper is a material of interest to Additive Manufacturing (AM) owing to its outstanding material properties, which finds use in enhanced heat transfer and electronics applications. Its high thermal conductivity and reflectivity cause challenges in the use of Powder Bed Fusion AM systems that involve supplying high-energy lasers or electron beams. This makes Binder Jetting a better alternative as it separates part creation (binding together of powders) from energy supply (post-process sintering). However, it is challenging to fabricate parts of high density using this method due to low packing density of powder while printing. This work aims to investigate the effects of Hot Isostatic Pressing (HIP) as a secondary post-processing step on the densification of Binder Jet copper parts. By understanding the effects of HIP, the author attempts to create parts of near-full density, and subsequently to quantify the effects of the developed process chain on the material properties of resultant copper parts. The goal is to be able to print parts of desired properties suited to particular applications through control of the processing conditions, and hence the porosity. First, 99.47% dense copper was fabricated using optimized powder configurations and process parameters. Further, the HIP of parts sintered to three densities using different powder configurations was shown to result in an improvement in strength and ductility with porosity in spite of grain coarsening. The strength, ductility, thermal and electrical conductivity were then compared to various physical and empirical models in the literature to develop an understanding of the process-property-performance relationship. / Master of Science / Additive Manufacturing (AM) is a technique of fabricating an object in a layer-wise fashion. The layer-based approach provides opportunity for the manufacture of highly complex shapes. Binder Jetting is an AM technology that creates parts by the selective jetting of a polymeric binder onto successive layers of powdered material. In the case of metals, the printing process is followed by sintering in an oven, which burns out the binder and densifies the part. However, this is typically not enough to remove all the porosity in a specimen. While this enables the fabrication of a variety of materials, the porosity in sintered parts can be a detriment to their properties. This work aims to investigate the use of post-process Hot Isostatic Pressing (HIP) to eliminate the remaining porosity. HIP is a technique of applying high pressures at high temperatures in an inert gas medium. The goal of this research is to scientifically understand and quantify the effect of HIP on sintered parts made via Binder Jetting. The research is carried out in the context of copper, which has unique mechanical, thermal and electrical conductance properties that could be influenced by the presence of pores. In this work, the effects of the Binder Jetting-Sintering-HIP process chain on the porosity, and consequently the material properties, of copper parts are quantified. Resolving the issue of porosity can enable the printing of copper parts for specialized applications from electronic components to rocket engines. Developing a quantitative understanding can pave the way to design specific processing conditions to fabricate not only fully dense copper parts with superior properties, but also parts of a designed level of porosity that have specific target material properties.

Projektet gick ut på att montera ihop en Binder Jetting 3D-skrivare som är en delav ett större projekt med syfte att framställa individanpassade läkemedel inomsjukvården. Skrivaren fungerar genom att om vartannat applicera tunna skiktpulver och bindemedel. Under konstruktionen av skrivaren tillverkades ett Boost-Demultiplexer kretskort, skrivarens chassi monterades; varpå bland annat axlar,matarkolvar och byggkolvar, spridare och motorer fästes. Slutligen drogselektronik mellan de olika komponenterna och inställningar gjordes i både firmwareoch mjukvara. För att testa skrivaren skrevs en kalibreringskub med måtten 20x20x20 mm ut,först utan pulver på ett pappersark för att avgöra om skrivarhuvudets rörelse varkorrekt, sedan i 3D med gips i pulverform och skrivarbläck som bindemedel. Frånutskriften på papper framgick det att skrivarhuvudet rör sig som önskat, däremothöll inte 3D-utskriften ihop. Detta förklaras med att bläcket inte band ihop gipsettillräckligt bra. Dock bekräftades att både matarsystemet och skrivytan rör sig somtänkt, eftersom skrivytan rört sig nedåt lika långt som utskriften krävde. Med ettlämpligare bindningsmedel antas därför skrivaren vara fullt funktionell, även omingen konkret slutsats kan dras från testutskrifterna.

Additive manufacturing brings versatility and new degree of freedom for part design and manufacturing possibilities. Binder jetting is powder bed printing technique that does not require direct energy transfer rather binding powder metal particles through mechanical entanglement by use of the organic binder. The polymer chains in the solution hardens when heated thus creating a green part. Green parts are sintered in high temperature to adhere metal powder particles together creating a solid body. Binder jetting still developing to its full potential in scalability and material portfolio. This thesis aims to contribute know how in process and material development of H13 tool steel in very fine particle size distributions from -16 µm to -10µm. Process parameters as well as sintering cycle developed specifically for H13 fine powders. With 52 samples printed, sintered in four different temperatures and analyzed material properties such as density and hardness to evaluate how particle size distributions affect printing process, densification and shrinkage in the sintering. Density of the green body has been evaluated through measurements of dimensions and weight, sintered density was analyzed by Archimedes method and light optical metallography. Trials for the processing and evaluation of the powders concluded that it is possible to use ultra-fine PSDs in binder jetting process with good results, this opens up opportunity for increased sustainability and profitability for powder manufacturing industry. Particle size distribution of -10 µm has outperformed the -16 µm in areas of relative density of the green body, sintered density and hardness. Although superior performance, the -10 µm requires higher ultrasonic intensity and lower spreading speed to achieve homogeneous powder bed. For the -16 µm powder it is worth noting that it is possible to bring up green density with further process development. Although materials presented high hardness in as printed state compared to that of PIM manufactured parts, achieved hardness is not satisfactory for the applications of the alloy and requires heat treatment corresponding to customer requirements.