Slice overlap-detection algorithm for process planning in multiple-material stereolithography

Kim, Ho-Chan; Choi, Jae Won; MacDonald, Eric; Wicker, Ryan B.

doi:10.1007/s00170-009-2181-x

Cited by 18 publications

(10 citation statements)

References 14 publications

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“…The majority of reports to date employ custom-made printers to enable multimaterial printing capabilities that are not achievable with commercial 3D printers. Customizations include supplementary mechanical components capable of removing one material, cleaning the resin vat and/or partially printed part, and adding the new material. ,− ,,,,− ,, These novel designs are also described in several patents. ,,,, The pioneering work on these custom printers was first investigated by Wicker’s group, followed by Choi’s group. ,,,,− ,, Wicker’s system, based on a retrofitted SLA with a rotating vat carousel system (Figure a), was further improved with an automatic resin leveling system (floating target). ,,− ,, They also developed a PμSLA with an automatic resin syringe pump to dispense the desired volume of resin followed by steps to manually remove and clean the vat . Choi’s group used two stages with vertical adjustment to facilitate resin vat exchange .…”

Section: Multimaterials Methodsmentioning

confidence: 99%

“…(e) Optimization of the number of printing steps for free surface vat polymerization using software programming such that the number of steps can be decreased from six (left) to four (middle) to three (right) steps by printing many layers of one material until an interface is reached. Reprinted with permission from ref . Copyright 2010 Springer Nature.…”

Section: Multimaterials Methodsmentioning

confidence: 99%

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Multimaterial Vat Polymerization Additive Manufacturing

Sampson

Deore

et al. 2021

ACS Appl. Polym. Mater.

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Additive manufacturing is the process of creating an object from a digital three-dimensional (3D) design using hardware that deposits and adds materials successively until the desired object is formed. Vat polymerization is a type of additive manufacturing technique that offers an attractive strategy for fabricating 3D objects due to its high resolution, versatility of feedstock materials, and high dimensional accuracy. However, the ability to spatially control the placement of multiple materials during vat polymerization is limited by mechanical designs that can restrict printing to a single photocurable resin, making it difficult to create complex geometries with embedded functionality. In this review, we highlight work-arounds that have been employed, such as manually switching resins, as well as two key areas of innovation: mechanical hardware design and the chemistry of materials. These methods include systems which automatically switch resin vats, volumetric additive manufacturing which overprints a secondary 3D structure on top of an existing object, and specially formulated, unique material chemistries, such as those which enable dual wavelength light to initiate orthogonal chemistry mechanisms, control of the degree of cross-linking with variation in light parameters, and phase separation of functional materials. Perspectives on the interplay of printer type and material chemistry, the constraints they impose on one another, and the future of multimaterial vat polymerization are described. In order for vat polymerization to emerge as a viable technology for multimaterial additive manufacturing, both mechanical hardware design and chemistry of materials must be codeveloped.

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Section: Multimaterials Methodsmentioning

confidence: 99%

Section: Multimaterials Methodsmentioning

confidence: 99%

Multimaterial Vat Polymerization Additive Manufacturing

Sampson

Deore

et al. 2021

ACS Appl. Polym. Mater.

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“…The overlap detection algorithm for the third case is shown in Figure 10 (more details of this algorithm can be found in Kim et al (2010)). The material changeover can be determined by examining overlap between loops.…”

Section: Rules and Algorithm For Scheduling And Process Planningmentioning

confidence: 99%

Scheduling and process planning for multiple material stereolithography

Kim

Choi

Wicker

2010

Rapid Prototyping Journal

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PurposeTo operate a multiple material stereolithography (MMSL) system, a material build schedule is required. The purpose of this paper is to describe a scheduling and process‐planning software system developed for MMSL and designed to minimize the number of material changeovers by using low‐viscosity resins that do not require sweeping.Design/methodology/approachThis paper employs the concept of using low‐viscosity resins that do not require sweeping to minimize the number of material changeovers required in MMSL fabrication. A scheduling and process‐planning software system specific to MMSL is introduced that implements four simple rules. Two rules are used to select the material to be built in the current layer, and two rules are used to determine at which layer a material changeover is required. The schedule for the material to be built depends on the material properties stored in a user‐defined materials library. The developed algorithm produces sliced loop data for each material using the predetermined layer thickness from an input CAD model, and the four rules are applied at each layer. The algorithm then determines the build order for each material, the material‐specific number of layers to be built, and whether or not sweeping is required. Output data from the program are the scheduling and process‐planning report and the partitioned computer‐aided design models to be built before changing a material according to the process planning. Two examples of the algorithm applied to multiple material parts are provided.FindingsThe MMSL scheduling and process‐planning software system is developed using Microsoft Visual C++7.0. For verification, a simple demonstration is conducted on a two material part where the process plan could be easily determined through intuition. A more complex multiple material part is also tested that consisted of four subparts. Several cases of resin assignment are tested showing that the ultimate scheduling and process planning vary significantly depending on the material combinations and specifications. These examples demonstrate that the strategy, method, and software developed in this paper can be successfully applied to prepare for MMSL fabrication.Research limitations/implicationsAlthough the software system is demonstrated on two multiple material parts, more extensive work will be performed in the future on fabricating multiple material parts using the MMSL machine. It is expected that additional rules will be developed as additional limitations of MMSL are identified. It is also anticipated that particular emphasis will be placed on building without sweeping as well as development of advanced non‐contact recoating processes.Originality/valueAs designs incorporating multiple materials increase in the future and additive manufacturing (AM) technologies advance in both building out of multiple materials and fabricating production parts, the scheduling and process‐planning concepts presented here can be applied to virtually any AM technology.

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“…However, the problem of material waste and residual cleaning still remains as top-down stereolithography requires the part under construction to fully immerse in the liquid material during fabrication. Process planning algorithms (Kim et al, 2010;Lopes et al, 2010) were developed to minimize the material changeovers based on the a priori decision of the maximum number of layers that could be continuously built in one material vat.…”

Section: Introductionmentioning

confidence: 99%

Biphasic osteochondral scaffold fabrication using multi-material mask projection stereolithography

Lian

et al. 2019

RPJ

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Purpose This study aims to develop a multi-material stereolithography (MMSL) technique to directly fabricate a biphasic osteochondral scaffold. Design/methodology/approach A bespoke prototype MMSL system was developed based on a bottom-up mask projection approach. The system was controlled by a multi-material fabrication algorithm with minimum number of switching cycles during fabrication. A variable-power light source was used to fabricate materials with significantly different curing characteristics. The light-curable poly(ethylene glycol) diacrylate (PEGDA) hydrogel and beta-tricalcium phosphate (β-TCP) ceramic suspension were used for fabricating the biphasic osteochondral scaffold. Findings The bonding strength of the multi-material interface is shown to be mainly affected by the type of photopolymer, rather than the switching of the materials in MMSL. Lighting power densities of 2.64 and 14.98 mW/cm2 were used for curing the PEGDA hydrogel and the ß-TCP ceramic suspension, respectively. A biphasic osteochondral scaffold with complex interface was successfully fabricated. Originality/value This study proposes a potential technical method (MMSL) for manufacturing a complex biphasic osteochondral scaffold composing a PEGDA hydrogel/ß-TCP ceramic composite in a time-efficient and precise manner. The designed bone-cartilage scaffold interface and the surface of the cartilage scaffold can be precisely manufactured.

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Slice overlap-detection algorithm for process planning in multiple-material stereolithography

Cited by 18 publications

References 14 publications

Multimaterial Vat Polymerization Additive Manufacturing

Multimaterial Vat Polymerization Additive Manufacturing

Scheduling and process planning for multiple material stereolithography

Biphasic osteochondral scaffold fabrication using multi-material mask projection stereolithography

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