Stereolithography

The present decade has witnessed a huge volume of research revolving around a number of Additive Manufacturing (AM) techniques, especially for the fabrication of different metallic materials. However, fabrication of ceramics and cermets using AM-based techniques mainly suffers from two primary limitations which are: (i) low density and (ii) poor mechanical properties of the final components. Although there has been a considerable volume of work on AM based techniques for manufacturing ceramic and cermet parts with enhanced densities and improved mechanical properties, however, there is limited understanding on the correlation of microstructure of AM-based ceramic and cermet components with the mechanical properties. The present article is aimed to review some of the most commonly used AM techniques for the fabrication of ceramics and cermets. This has been followed by a brief discussion on the microstructural developments during different AM-based techniques. In addition, an overvie...

In recent years, additive manufacturing (AM) or rapid prototyping (RP) technologies, initially developed to create prototypes prior to production for the automotive, aerospace, and other industries, have found applications in tissue engineering (TE) and their use is growing ...

Stereolithography process limits wider applications due to low dimensional accuracy comparing with CNC process. Hence, to improve accuracy and reduce part distortion, understanding the physics involved in the relationship between the setup input parameters and the part dimensional accuracy is prerequisite. In this paper, a model is proposed to find and optimize important parameters to achieve higher accuracy and also predict dimensional accuracy using various parameters values. For this purpose, the result of a previous study is used, where it is found that in stereolithography process these factors in order of importance with respect to dimensional accuracy are: layer thickness, hatch style, hatch spacing, hatch fill cure depth and hatch overcure. Moreover, in this research the proposed neural network model is able to predict dimensional accuracy with 6% error.

Additive manufacturing (AM) technologies play a very significant role in making metallic/nonmetallic prototypes or products in layered fashion. The main goal of these technologies is to produce fully dense and net shaped metal/non-metal parts in single step. Some additive manufacturing technologies such as Selective Laser Sintering and Laser Engineered Net Shaping are dominating processes while Laminated Object Manufacturing has also been used. This paper tries to present a comparative picture of the different additive manufacturing technologies.

3D printing has been admired as a cutting-edge technology, which will change manufacturing [1]. Recent advances in bioprinting technologies have enabled rapid manufacturing of medical models in many fields and areas. Recently in the field of dentistry, fused deposition modeling and Stereolithography 3D bioprinting techniques have been using in dental applications such as implants, the production of physical models for prosthodontics, orthodontics, and surgery [2,3]. This paper reviews the usage of fused deposition modeling and stereolithography 3D printing technologies and their various applications in dentistry and in maxillofacial surgery. 3D printing is transforming digital dentistry by extensively penetrating opportunities in diagnosis, treatment and education. The accel- erated research in this industry and optimism would open more doors to help revolutionize digital dentistry.

Keywords: Fused Deposition Modeling (FDM); Stereolithography (SLA); 3D Printing; Dentistry, Dental Devices

Rapid-Prototyping (RP) is a group of techniques used to quickly fabricate a scale model of a physical part or assembly using three-dimensional Computer Aided Design (CAD) data. There are two phases in the birth of a product, first would be the design phase and second would be the manufacturing phase. Both the processes involve several steps as per design and manufacturing guidelines. In this competitive age any time reduction in these steps will help in profit maximization. Apart from the conventional manufacturing processes which are used for several years while manufacturing of a product, additive manufacturing processes have gained momentum in the recent years. The reason behind this is that these processes do not require special tooling and do not remove material which is very beneficial in the making of a component. In this review paper, an attempt has been made to know the insights of one such additive manufacturing process i.e., Fused Deposition Modeling (FDM).

Magnetic nanocomposite scaffolds based on poly(e-caprolactone) and poly(ethylene glycol) were fabricated by 3D fibre deposition modelling (FDM) and stere-olithography techniques. In addition, hybrid coaxial and bilayer magnetic scaffolds were produced by combining such techniques. The aim of the current research was to analyse some structural and functional features of 3D magnetic scaffolds obtained by the 3D fibre deposition technique and by stereolithography as well as features of multimaterial scaffolds in the form of coaxial and bilayer structures obtained by the proper integration of such methods. The compressive mechanical behaviour of these scaffolds was investigated in a wet environment at 37 °C, and the morphological features were analysed through scanning electron microscopy (SEM) and X-ray micro-computed tomography. The capability of a magnetic scaffold to absorb magnetic nanoparticles (MNPs) in water solution was also assessed. confocal laser scanning microscopy was used to assess the in vitro biological behaviour of human mes-enchymal stem cells (hMSCs) seeded on 3D structures. Results showed that a wide range of mechanical properties, covering those spanning hard and soft tissues, can be obtained by 3D FDM and stereolithography techniques. 3D virtual reconstruction and SEM showed the precision with which the scaffolds were fabricated, and a good-quality interface between poly(e-caprolactone) and poly(ethylene glycol) based scaffolds was observed for bilayer and coaxial scaffolds. Magnetised scaffolds are capable of absorbing water solution of MNPs, and a preliminary information on cell adhesion and spreading of hMSCs was obtained without the application of an external magnetic field.

Due to the availability, biodegradability, and biological effects, lignin has emerged as an interesting alternative to petroleum-based compounds for developing sustainable chemicals, materials, and composites. In this study, lignin at various concentrations was incorporated into methacrylate resin via solution blending to fabricate lignin-reinforced composites using stereolithography apparatus three-dimensional printing. Softwood kraft lignin in the amounts of 0.2, 0.4, 0.5, 0.8, and 1.0 wt % in the methacrylate resin was used as a printing ink, and the gel contents and relative contents of the residual resin in the printed samples with various lignin concentrations were measured. The effects of the lignin on the ultimate mechanical properties of the non-postcured and postcured printed composites were determined. The tensile testing results revealed that the incorporation of lignin in the composite increased the tensile strength by 46−64% and Young's modulus by 13−37% for the postcured printed composites compared with that of the control sample (no lignin added). Employing a 0.4 wt % softwood kraft lignin, the tensile strength of the postcured printed composite reached the highest value of 49.0 MPa, which was a 60% increase in comparison to that of the control sample with 30.7 MPa. Scanning electron microscopy images of the fracture samples illustrated that the lignin-incorporated composites exhibited a rougher fracture surface that can presumably dissipate the stress, which could be a contributing factor for the mechanical enhancement.

In this work, we assess the effects of sterilization in materials manufactured using additive manufacturing by employing a sterilization technique used in the food industry. To estimate the feasibility of the hydrostatic high-pressure (HHP) sterilization of biomedical devices, we have evaluated the mechanical properties of specimens produced by commercial 3D printers. Evaluations of the potential advantages and drawbacks of Fused Deposition Modeling (FDM), Digital Light Processing (DLP) technology, and Stereolithography (SLA) were considered for this study due to their widespread availability. Changes in mechanical properties due to the proposed sterilization technique were compared to values derived from the standardized autoclaving methodology. Enhancement of the mechanical properties of samples treated with Hydrostatic high-pressure processing enhanced mechanical properties, with a 30.30% increase in the tensile modulus and a 26.36% increase in the ultimate tensile strength. While traditional autoclaving was shown to systematically reduce the mechanical properties of the materials employed and damages and deformation on the surfaces were observed, HHP offered an alternative for sterilization without employing heat. These results suggest that while forgoing high-temperature for sanitization, HHP processing can be employed to take advantage of the flexibility of additive manufacturing technologies for manufacturing implants, instruments, and other devices.

Papers and magazines announce a new industrial revolution. An apparently innovative technology, but created on the past century, is spreading very fast through technology enthusiasts and industries looking for a cost reduction on their development processes. Machines that, thirty years ago, costly tens thousands of dollars, are now being produced at home and being sold for hundreds of dollars. The 3D printing era has come. In this case study, will be shown the impact of spreading this new technology will bring us, especially, to small companies with a very limited resources that, before, had difficulties to produce and test your mechanical parts prototypes while developing new projects. With a small budget, this companies today, are not only producing their prototypes but, accelerating their developments, and consequently, reducing the time to market of new products. This study shows a comparison between conventional manufacturing processes with addictive manufacture, especially on costs and time.

Keywords: Addictive Manufacture; 3D Printing; Prototyping; FDM; SLA;

Lab-on-a-Chips integrate a variety of laboratory functions and embed microchannels for small fluid volume handling. These devices are used in medicine, chemistry, and biotechnology applications but a large diffusion is limited due to the manufacturing cost of traditional processes. Additive Manufacturing offers affordable alternatives for the production of microfluidic devices, because the fabrication of embedded micrometric channels is enabled. Stereolithography gained particular attention due to the low cost of both available machines and suitable polymeric materials to be processed. The main restriction to the adoption of this technique comes from the obtainable dimensional accuracy that depends not only on design, but also on process set-up. Firstly, the paper analyses theoretically the physics of stereolithographic processes and focuses on main phenomena related to microchannel manufacturing. Then, specific experimental activities are designed to investigate the combined effect...

Objectives: Rapid prototyping (RP) technology is becoming more affordable, faster, and is now capable of building models with a high resolution and accuracy. Due to technological limitations, 3D printing in biological anthropology has been mostly limited to museum displays and forensic reconstructions. In this study, we compared the accuracy of different 3D printers to establish whether RP can be used effectively to reproduce anthropological dental collections, potentially replacing access to oftentimes fragile and irreplaceable original material. Methods: We digitized specimens from the Yuendumu collection of Australian Aboriginal dental casts using a high-resolution white-light scanning system and reproduced them using four different 3D printing technologies: stereolithography (SLA); fused deposition modeling (FDM); binder-jetting; and material-jetting. We compared the deviations between the original 3D surface models with 3D print scans using color maps generated from a 3D metric deviation analysis. Results: The 3D printed models reproduced both the detail and discrete morphology of the scanned dental casts. The results of the metric deviation analysis demonstrate that all 3D print models were accurate, with only a few small areas of high deviations. The material-jetting and SLA printers were found to perform better than the other two printing machines. Conclusions: The quality of current commercial 3D printers has reached a good level of accuracy and detail reproduction. However, the costs and printing times limit its application to produce large sample numbers for use in most anthropological studies. Nonetheless, RP offers a viable option to preserve numerically constraint fragile skeletal and dental material in paleoan-thropological collections.

Introduction: Additive production refers to the process of prototyping, which allows the production of highly complex medical devices and products. Interpretation of additive manufacturing (AM) material in Computed Tomography (CT) has not been widely investigated. The aim of this study was to determine the CT number values of commercially available fused deposition modelling (FDM) and stereolithography (SLA) AM materials. Methods: Total of 15 AM materials, 7 FMD and 8 SLA, were selected and scanned on CT to determine the HU value and appearance on the images. All test object were designed as rectangular blocks and after their production physical description were calculated. AM materials were scanned on CT operating at 80, 100, 120 and 135 kV. Results: All materials correspond to a certain human tissue and they have uniformity when printed with 100% infill. CT number ranged from a minimum of À188.0 HU to a maximum of 189.1 HU, for FDM materials, and from À15.8 HU to 167.3 HU, for SLA materials. Conclusion: Knowing the CT number of an AM materials can allow the design of medical or rehabilitation products with a specific appearance on CT images. Analysed and collected data can find application in the design and manufacture of immobilization devices that can be easily distinguished from other materials or human tissue. Implications for practice: This study provides information that can be used in the design and fabrication of anthropomorphic diagnostic and therapeutic phantoms. There is significant potential for the use of AM material for sophisticated test objects when used in medical image modality testing. Knowing actual CT numbers of frequently used AM materials allows manufacturing anthropomorphic phantoms to investigate radiation doses in diagnostic radiology and radiotherapy.

The introduction of three-dimensional printing (3DP) has created exciting possibilities for the fabrication of dosage forms, paving the way for personalized medicine. In this study, oral dosage forms of two drug concentrations, namely 2.50% and 5.00%, were fabricated via stereolithography (SLA) using a novel photopolymerizable resin formulation based on a monomer mixture that, to date, has not been reported in the literature, with paracetamol and aspirin selected as model drugs. In order to produce the dosage forms, the ratio of poly(ethylene glycol) diacrylate (PEGDA) to poly(caprolactone) triol was varied with diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (Irgacure TPO) utilized as the photoinitiator. The fabrication of 28 dosages in one print process was possible and the printed dosage forms were characterized for their drug release properties. It was established that both drugs displayed a sustained release over a 24-h period. The physical properties were also investigated, il...

The 3D printing of nasopharyngeal swabs during the COVID‐19 pandemic presents a central case of how to efficiently address a break in the global supply chain of medical equipment. Herein a comprehensive study of swab design considerations for mass production by stereolithography is presented. The retention and comfort performance of a range of novel designs of 3D‐printed swabs are compared with the standard flocked‐head swab used in clinical environments. Sample retention of the 3D swab is governed by the volume, porosity density, and void fraction of the head as well as by the pore geometry. 3D‐printed swabs outperform conventional flock‐head swabs in terms of sample retention. It is argued that mechanically functional designs of the swab head, such as corkscrew‐shaped heads and negative Poisson ratio heads, maximize sample retention and improve patient comfort. In addition, available designs of swab shafts for an optimized sample collection procedure are characterized. The study is conducted in vitro, using artificial mucus, covering the full range of human mucus viscosities in a 3D‐printed model of a nasal cavity. The work sets the path for the resilient supply of widespread sterile testing equipment as a rapid response to the current and future pandemics.

Mask Projection micro-Stereolithography (MPμSL) is an additive manufacturing technique capable of producing solid parts with micron-scale resolution from a vat of photocurable liquid polymer resin. Although the physical mechanism remains the same, the process differs from traditional laser-galvanometer based stereolithography (SL) in its use of a dynamic mask UV projector, or digital light processor (DLP), which cures each location within each 3D layer at the same time. One area where MPμSL has garnered considerable attention is in the field of microfluidics and Lab-on-a-Chip, where complex multistep microfabrication techniques adopted from the semiconductor industry are still widely used, and where MPμSL offers the ability to fabricate completely encapsulated fluidic channels in a single step and at low cost [1–3]. However, a significant obstacle exists in the prevention of channel blockage due to overcuring of the polymer resin [4, 5]. Overcuring can be attributed to the so-called...

Stereolithography is highly versatile and precise process of solid free form additive manufacturing technique. Process requires biocompatible liquid photopolymer resin as a material which is one of the limitation of the process also. Curing liquid resin with a high intensity UV radiations at times causes over-curing which is highly undesirable. In this project, behavior of different biomaterials have been observed under same condition and the results have been plotted and regression analysis for each has been done. The study of graphs and coefficient of determination of process with different materials shows how accurate the process is and it also helps ultimately to conclude the linear relationship between curing depth and exposure time. In any stereolithography case these curing depth and exposure time are chief governing parameters along with critical exposure and penetration depth.

In this study, the printing capability of two different additive manufacturing (3D printing) techniques, namely PolyJet and micro-stereolithography (µSLA), are investigated regarding the fabrication of bone scaffolds. The 3D-printed scaffold structures are used as supports in replacing and repairing fractured bone tissue. Printed bone scaffolds with complex structures produced using additive manufacturing technology can mimic the mechanical properties of natural human bone, providing lightweight structures with modifiable porosity levels. In this study, 3D scaffold structures are designed with different combinations of architectural parameters. The dimensional accuracy, permeability, and mechanical properties of complex 3D-printed scaffold structures are analyzed to compare the advantages and drawbacks associated with the two techniques. The fluid flow rates through the 3D-printed scaffold structures are measured and Darcy’s law is applied to calculate the experimentally measured pe...

This paper illustrates the role of additive manufacturing (AM) as enabling technology to realize high-performance low-cost antennas for Ka-band applications. In addition to the inherent electromagnetic challenges implicit in the conception of such complex devices, this paper also points out the stringent limitations that appear when opting for classical fabrication techniques, based on assembled split-block models. AM emerges in this context as a change of paradigm, allowing monolithic fabrication and design freedom, which result in substantial improvements in terms of compactness, mass, simplicity, cost, and production time. Two different antennas for Ka-band satellite communications are presented here, namely a wideband horn and a dual-band circular cavity. Both prototypes are fabricated using a stereolithographic (SLA) AM process followed by metal coating. This fabrication approach is especially well suited to the implementation of these designs, since they have internal shapes that are inaccessible to conventional machining tools. The experimental results are not only in very good agreement with the theoretical predictions but also demonstrate improvements over the performances achieved by traditional milling and assembly fabrication approaches, thereby confirming the validity and great potential of SLA for Ka-band satellite communications.

Magnetic nanocomposite scaffolds based on poly(ε-caprolactone) and poly(ethylene glycol) were fabricated by 3D fibre deposition modelling (FDM) and stereolithography techniques. In addition, hybrid coaxial and bilayer magnetic scaffolds were produced by combining such techniques. The aim of the current research was to analyse some structural and functional features of 3D magnetic scaffolds obtained by the 3D fibre deposition technique and by stereolithography as well as features of multimaterial scaffolds in the form of coaxial and bilayer structures obtained by the proper integration of such methods. The compressive mechanical behaviour of these scaffolds was investigated in a wet environment at 37 °C, and the morphological features were analysed through scanning electron microscopy (SEM) and X-ray micro-computed tomography. The capability of a magnetic scaffold to absorb magnetic nanoparticles (MNPs) in water solution was also assessed. confocal laser scanning microscopy was used ...

Chapter 2 History of Stereolithographic Processes Paulo Jorge Bartolo and Ian Gibson 2.1 Introduction There are a number of processes that can ... I. Madrazo, C. Zamorano, E. Magallon, T. Valenzuela, A. Ibarra, H. Salgado-Ceballos, I. Grijalva, RE Franco-Bourland, G. Guízar ...

Mask Projection micro-Stereolithography (MPμSL) is an additive manufacturing technique capable of producing solid parts with micron-scale resolution from a vat of photocurable liquid polymer resin. Although the physical mechanism remains the same, the process differs from traditional laser-galvanometer based stereolithography (SL) in its use of a dynamic mask UV projector, or digital light processor (DLP), which cures each location within each 3D layer at the same time. One area where MPμSL has garnered considerable attention is in the field of microfluidics and Lab-on-a-Chip, where complex multistep microfabrication techniques adopted from the semiconductor industry are still widely used, and where MPμSL offers the ability to fabricate completely encapsulated fluidic channels in a single step and at low cost [1–3]. However, a significant obstacle exists in the prevention of channel blockage due to overcuring of the polymer resin [4, 5]. Overcuring can be attributed to the so-called ‘back side effect’ [2] which occurs during the build process as light from successive layers penetrates into the resin to a depth greater than the layer thickness. This effect is most prevalent in channels or features oriented horizontally (in a parallel plane to that of the build platform). Currently there are two main approaches in controlling the cure depth; 1. the chemical approach, which involves doping the resin material with a chemical light absorber [6–8]; and 2. by improving the system’s hardware and optical elements to improve the homogeneity of the light dosage and control the cure depth [9]. Here we investigate a third approach through modification of the 3D CAD file prior to printing to mitigate for UV light leakage from successive build layers. Although used here in conjunction with the MPμSL technique, this approach can be applied to a range of SL techniques to improve printer resolution and enable production of internal features with higher dimensional accuracy.

The paper’s aim is to investigate the influence of added light absorber (Tinuvin® 327) on dimension accuracy of three-dimensional (3D) micro-parts manufactured by a dynamic mask projection microstereolithography (μSL) system. One of the common problems with stereolithography systems, and particularly with μSL is the uncontrolled cure depth of the UV light when fabricating down-facing surfaces. To overcome this problem, light absorber is commonly used to control the cure depth. Yet the influence of light absorber on the dimension accuracy of manufactured parts is not fully understood and needs to be investigated. This work explores the effect on part accuracy of adding four different concentrations of Tinuvin®327 to PIC-100 acrylate resin without light absorber. A benchmark part has been designed to evaluate the effect of the added Tinuvin®327 on linear, position, and geometric dimensions. Results show that Tinuvin®327 has significant effects on part accuracy.

The first example of the fabrication of complex 3D polymer-derived-ceramic structures is presented with micrometer scale features by a 3D additive manufacturing (AM) technology, starting with a photosensitive preceramic precursor. Dense and crack-free silicon oxycarbide-based microparts with features down to 200 μm are obtained after pyrolysis at 1000 °C in a nitrogen atmosphere.

Chapter 2 History of Stereolithographic Processes Paulo Jorge Bartolo and Ian Gibson 2.1 Introduction There are a number of processes that can ... I. Madrazo, C. Zamorano, E. Magallon, T. Valenzuela, A. Ibarra, H. Salgado-Ceballos, I. Grijalva, RE Franco-Bourland, G. Guízar ...

Lab-on-a-Chips integrate a variety of laboratory functions and embed microchannels for small fluid volume handling. These devices are used in medicine, chemistry, and biotechnology applications but a large diffusion is limited due to the manufacturing cost of traditional processes. Additive Manufacturing offers affordable alternatives for the production of microfluidic devices, because the fabrication of embedded micrometric channels is enabled. Stereolithography gained particular attention due to the low cost of both available machines and suitable polymeric materials to be processed. The main restriction to the adoption of this technique comes from the obtainable dimensional accuracy that depends not only on design, but also on process set-up. Firstly, the paper analyses theoretically the physics of stereolithographic processes and focuses on main phenomena related to microchannel manufacturing. Then, specific experimental activities are designed to investigate the combined effect...

Lab-on-a-Chips integrate a variety of laboratory functions and embed microchannels for small fluid volume handling. These devices are used in medicine, chemistry, and biotechnology applications but a large diffusion is limited due to the manufacturing cost of traditional processes. Additive Manufacturing offers affordable alternatives for the production of microfluidic devices, because the fabrication of embedded micrometric channels is enabled. Stereolithography gained particular attention due to the low cost of both available machines and suitable polymeric materials to be processed. The main restriction to the adoption of this technique comes from the obtainable dimensional accuracy that depends not only on design, but also on process set-up. Firstly, the paper analyses theoretically the physics of stereolithographic processes and focuses on main phenomena related to microchannel manufacturing. Then, specific experimental activities are designed to investigate the combined effect...