Development of a variable tensioning system to reduce separation force in large scale stereolithography

Song, Haiyan; Rodriguez, Nicholas; Seepersad, Carolyn Conner; Crawford, Richard H.; Chen, Morgan; Duoss, Eric B.

doi:10.1016/j.addma.2020.101816

Cited by 10 publications

(6 citation statements)

References 33 publications

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“…It requires a transparent resin and objects are printed by selectively polymerizing the resin with a UV laser. This allows for a high spatial resolution, but the necessity to create objects in a resin bath limit this technology to the centimetre scale [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Investigation of a hybrid binder system for large scale 3D printing

Remke,

Sant,

Gädt

2023

ce papers

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Large‐scale additive manufacturing of reactive suspensions, such as concrete, is being developed to freely create objects without the constraints of a formwork. One challenge in printing suspensions is the precise spatio‐temporal control over their rheological properties. For extrusion‐based processes the material must be pumpable to the nozzle of the printer, while once it has passed the nozzle, it must maintain its shape under the increasing pressure of subsequent layers. Therefore, it is beneficial if the material exhibits an appropriately designed rheology change at the nozzle. The objective of this work is to develop a printing suspension which achieves a rheological step change at the nozzle. Therefore, we create a hybrid binder system comprising of a fast, reactive organic component, which can be activated by heat and a second inorganic binder components, in our system the carbonation of calcium hydroxide, which delivers the final strength.The temperature dependent stiffening of the model suspensions is studied by oscillatory rheology at temperatures between 20 °C to 80 °C. For mechanical testing purposes, cuboid shaped samples are obtained by microwave heating followed by carbonation under ambient conditions. For the given porosity, the material reaches a compressive strength of up to 0.39 MPa in 10 seconds or up to 1.94 MPa in 10 minutes depending on the heating program. Subsequent carbonation for 7 days under ambient conditions gives a strength of up to 4.76 MPa.

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Section: Introductionmentioning

confidence: 99%

Investigation of a hybrid binder system for large scale 3D printing

Remke,

Sant,

Gädt

2023

ce papers

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“…Mainstream commercial printers based on SLA and DLP often combine lift, retract, and at times, slide actions to ensure the printed part detaches from the window smoothly. Other fabrication strategies include utilizing vibration techniques [15], adjusting the vat's orientation with each layer to manage resin distribution [17], modifying the tension of the vat lm [30], and employing hydraulic techniques for active separation [36]. Recently, continuous liquid interface production (CLIP) has signicantly accelerated printing by maintaining a thin liquid interface, the deadzone, between the growing part and the window, Anonymous Authors obviating the lift-and-retract mechanism of SLA and DLP-based printers [32].…”

Section: Introductionmentioning

confidence: 99%

Bioinspired fluidic design for additive manufacturing

Shaqfeh,

Lipkowitz,

Krishna

et al. 2023

Preprint

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While resin 3D printing affords designers unprecedented geometric complexity, currently the technology struggles to find real-world adoption in manufacturing settings due to slow print speeds, poor reliability, and cumbersome support structures. The last of these are not user-friendly in numerous ways; they are materially wasteful, human labor-intensive, time-consuming to remove, damaging to surface finish, and often unreliable in ensuring printability in the first place. These limitations are fundamentally related to adhesion forces and a lack of control of fluid flow during the printing process. Current design for additive manufacturing (DfAM) industry standards do not seek to offset such forces; instead, they empirically call for reducing printing speeds and/or imposing cumbersome supporting structures. Injection continuous liquid interface production (iCLIP) is a recent approach capable of effectively nullifying such forces by injecting resin into the deadzone. The method has been demonstrated to date for the case of a single channel running through an object formed of rigid material. However, the possibility of innervating the growing object with multiple channels -- possible to engineer into the CAD design uniquely for every print by this fabrication approach -- remains unexplored. Inspired by the complex three-dimensional fluidic distribution networks engineered by biological systems across scales, in this work we define and evaluate a qualitatively new bioinspired DfAM approach to accompany iCLIP, optimally innervating the part with channels to infuse resin into the deadzone. We detail our modeling approach for both single and multiple injection sites, and for Newtonian and non-Newtonian resins. After describing our hardware implementation to evaluate our approach, we provide experimental validation for our simulation-driven injection scheme, including using both rigid and elastomeric resins. We demonstrate such a bioinspired design approach can significantly increase print speed and reduce the need for supports in a user’s 3D model. In doing so, our approach promises to enhance the scalability of resin 3D printing to hasten its adoption in real-world manufacturing settings.

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“…Stereolithography or vat photopolymerisation is one of the most commonly used, and was the first commercialised AM method in which a photosensitive resin (photoresin) was used as the feedstock material loaded in a tray, which is often referred to as the “vat”. In bottom-up vat photopolymerisation 3D printing, the vat has a transparent film on its bottom plate that is located on a screen from which a light source (usually between 355–470 nm) illuminates the photoresin and cures it layer-by-layer to manufacture the desired 3D part [ 2 , 3 , 4 , 5 ]. Liquid crystal display (LCD) 3D printing, also known as masked stereolithography (MSLA), is a lithography-based AM technique in which LCD screens are used to cure photoresins in a layer-wise fashion [ 6 ].…”

Section: Introductionmentioning

confidence: 99%

“…As the viscosity of the monomers increases, their mobility decreases, and therefore lower monomer conversion occurs before the gelation stage. Although this suggests that the lower molecular weight monomers offer higher conversion rates, monomers and oligomers with higher molecular weights have superior mechanical properties, even at lower conversion, hence being referred to as “structural monomers” [ 3 , 4 , 9 ]. The presence of structural monomers often leads to higher viscosities, and they need to be diluted with low molecular weight monomers for a balanced viscosity, strength, and conversion rate.…”

Section: Introductionmentioning

confidence: 99%

Hot Lithography Vat Photopolymerisation 3D Printing: Vat Temperature vs. Mixture Design

et al. 2022

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In the vat photopolymerisation 3D printing technique, the properties of the printed parts are highly dependent on the degree of conversion of the monomers. The mechanisms and advantages of vat photopolymerisation at elevated temperatures, or so called “hot lithography”, were investigated in this paper. Two types of photoresins, commercially used as highly accurate castable resins, with different structural and diluent monomers, were employed in this study. Samples were printed at 25 °C, 40 °C, and 55 °C. The results show that hot lithography can significantly enhance the mechanical and dimensional properties of the printed parts and is more effective when there is a diluent with a network Tg close to the print temperature. When processed at 55 °C, Mixture A, which contains a diluent with a network Tg = 53 °C, was more readily impacted by heat compared to Mixture B, whose diluent had a network Tg = 105. As a result, a higher degree of conversion, followed by an increased Tg of the diluents, and improvements in the tensile strength and dimensional stability of the printed parts were observed, which enhanced the outcomes of the prints for the intended application in investment casting of complex components used in the aero and energy sectors. In conclusion, the effectiveness of the hot lithography process is contained by a correlation between the process temperature and the characteristics of the monomers in the mixture.

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Development of a variable tensioning system to reduce separation force in large scale stereolithography

Cited by 10 publications

References 33 publications

Investigation of a hybrid binder system for large scale 3D printing

Investigation of a hybrid binder system for large scale 3D printing

Bioinspired fluidic design for additive manufacturing

Hot Lithography Vat Photopolymerisation 3D Printing: Vat Temperature vs. Mixture Design

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