Study of separation force in constrained surface projection stereolithography

Pan, Yayue; He, Haiyang; Xu, Jie; Feinerman, Alan

doi:10.1108/rpj-12-2015-0188

Cited by 87 publications

(51 citation statements)

References 20 publications

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“…The average separation force is $18 N for each layer. Besides, there is no significant increase of separation force over the manufacturing process, which is often seen in conventional constrained surface SL processes [32,33]. The CAD model, fabricated picture, and the corresponding microscopic image are shown in Fig.…”

Section: Test Casementioning

confidence: 99%

Effect of Constrained Surface Texturing on Separation Force in Projection Stereolithography

et al. 2018

Journal of Manufacturing Science and Engineering

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In projection stereolithography (SL) processes, the separation of a newly cured layer from the constrained surface is a historical technical barrier and still greatly limits its printable size, process reliability, and print speed. This paper presents an approach to reduce the separation force in projection SL processes by texturing the constrained surface with radial microgroove patterns. Separation forces with conventional smooth constrained surface and textured surface are both modeled. The analytical model suggests that a proper design of micropatterns of the constrained surface is capable of reducing separation forces greatly. Furthermore, a projection SL testbed with online separation force monitoring unit is developed for experimental study. Experimental results verified the effectiveness of microsurface textures in reducing separation forces. Test cases also show that with the help of the proposed textured constrained surface, parts with wide solid cross sections that could not be printed using conventional methods were manufactured successfully. The influence of the textured constrained surface on the printed parts' surface roughness is studied, a gray scale projection approach is proposed to eliminate the influence and improve the surface quality of printed parts. Hence, the presented methods can help to improve the manufacturing capability of Projection SL processes.

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Section: Test Casementioning

confidence: 99%

Effect of Constrained Surface Texturing on Separation Force in Projection Stereolithography

et al. 2018

Journal of Manufacturing Science and Engineering

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“…We showed that the suction force in FLOAT hydrogel printing is several hundred times less than that in continuous resin printing. This can potentially be explained by the fluid mechanics theory of Stefan's adhesion where separation force is inversely proportional to the cube of the separation distance and linearly proportional to the fluid viscosity (23,32). Although we did not measure the dead zone thickness in our continuous resin printing, it should be smaller than that in the CLIP method (120 µm).…”

Section: Discussionmentioning

confidence: 93%

Fast 3D printing of large-scale biocompatible hydrogel models

Anandakrishnan

Guo

et al. 2020

Preprint

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Large scale cell-laden hydrogel models hold great promise for tissue repair and organ transplantation, but their fabrication is faced with challenges in achieving clinically-relevant size and hierarchical structures. 3D bioprinting is an emerging technology, but its application in large, solid hydrogel fabrication has been limited by the slow printing speed that can affect the part quality and the biological activity of the encapsulated cells. Here we present a Fast hydrogeL prOjection stereolithogrAphy Technology (FLOAT) that allows the creation of a centimeter-sized, multiscale solid hydrogel model within minutes. Through precisely controlling the photopolymerization condition, we established low suction force-driven, high-velocity flow of the hydrogel prepolymer that supports the continuous replenishment of the prepolymer solution below the curing part and the nonstop part growth. We showed that this process is unique to the hydrogel prepolymer without externally supplemented oxygen. The rapid printing of centimeter-sized hydrogel models using FLOAT was shown to significantly reduce the part deformation and cellular injury caused by the prolonged exposure to the environmental stresses in layer-by-layer based printing methods. Media perfusion in the printed vessel network was shown to promote cell survival and metabolic function in the deep core of the large-sized hydrogel model over long term. The FLOAT is compatible with multiple photocurable hydrogel materials and the printed scaffold supports the endothelialization of prefabricated vascular channels. Together, these studies demonstrate a rapid 3D hydrogel printing method and highlight the potential of this method in the fabrication of large-sized engineered tissue models.

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“…It is also found that a porous substrate with PDMS coating is possible to address this challenge by providing direct contact of the air and PDMS and thus supplying the oxygen continuously. Preliminary study has proved the feasibility of using the porous transparent substrate coated with PDMS film as the constrained surface in SL [20]. Hence, this paper will further investigate how to design such porous PDMS-coated constrained surfaces, and how the various design parameters will affect the performance of the constrained surface in SL process.…”

Section: A Novel Polydimethylsiloxane Constrained Window With Air-difmentioning

confidence: 99%

“…The blue dotted curve is the recorded separation force during the printing process using the newly developed constrained surface, which is a PDMS film with design 3 air-diffusion-channel. The separation force model developed in our previous work [20] has also been used to calculate the theoretical peak separation forces using the two constrained surfaces. The red and blue dashed lines represent the calculated theoretical peak separation forces.…”

Section: Layer-by-layer Printing Of Objects With Wide Solid Cross Secmentioning

confidence: 99%

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Air-Diffusion-Channel Constrained Surface Based Stereolithography for Three-Dimensional Printing of Objects With Wide Solid Cross Sections

Pan

Feinerman

et al. 2018

Journal of Manufacturing Science and Engineering

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Oxygen inhibition has been proved capable of reducing the separation force and enabling successful prints in constrained surface vat photopolymerization (CSVP) based three-dimensional (3D) printing processes. It has also been demonstrated as a key factor that determines the feasibility of the newly developed CSVP-based continuous 3D printing systems, such as the continuous liquid interface production. Despite its well-known importance, it is still largely unknown regarding how to control and enhance the oxygen inhibition in CSVP. To close this knowledge gap, this paper investigates the constrained surface design, which allows for continuous and sufficient air permeation to enhance the oxygen inhibition in CSVP systems. In this paper, a novel constrained surface with air-diffusion-channel is proposed. The influences of the air-diffusion-channel design parameters on the robustness of the constrained surface, the light transmission rate, and light intensity uniformity are studied. The thickness of the oxygen inhibition layer associated with the proposed constrained surface is studied analytically and experimentally. Experimental results show that the proposed air-diffusion-channel design is effective in maintaining and enhancing the oxygen-inhibition effect, and thus can increase the solid cross section size of printable parts.

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Study of separation force in constrained surface projection stereolithography

Abstract: The fulltext of this document has been downloaded 112 times since 2017* Users who downloaded this article also downloaded: (2017),"A novel projection based electro-stereolithography (PES) process for production of 3D polymer-particle composite objects",

Cited by 87 publications

References 20 publications

Effect of Constrained Surface Texturing on Separation Force in Projection Stereolithography

Effect of Constrained Surface Texturing on Separation Force in Projection Stereolithography

Fast 3D printing of large-scale biocompatible hydrogel models

Air-Diffusion-Channel Constrained Surface Based Stereolithography for Three-Dimensional Printing of Objects With Wide Solid Cross Sections

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