Abstract of 3d printing

Progressive 3D Printing Technology and Its Application in Medical Materials

Introduction

As an additive manufacturing (AM) technique, three-dimensional (3D) printing enables customized fabrication of 3D constructs based on computer aided design (CAD) software or images obtained from computed tomography (CT) and magnetic resonance imaging (MRI). Firstly developed in the 1980s, 3D printing technology was called rapid prototype technology and has been well applied in a variety of industries with different printing techniques and materials (Liaw and Guvendiren, 2017). With the rapid development of 3D printer, the overall 3D printing market grew to $9.9 billion in 2018 and is expected to reach $34.8 billion in 2024 (MarketsandMarkets, 2019). The medical 3D printing market is expected to maintain significant growth due to the huge potential demand for costumed medical products. Currently, with the expiry of many 3D printing patents (including stereolithography and selective laser sintering), 3D printers and products are becoming cheaper and easy to access (Rahman et al. , 2018).

3D printing technology has been widely applied in a variety of industries including aviation (Wong, 2016), geoscience (Ishutov et al., 2018), education (Smith and Jones, 2018), clothing (Markstedt et al., 2017), medical (Mitsouras et al., 2015; Giannopoulos et al., 2016), and pharmaceuticals (Orsi et al., 2015; Norman et al., 2017; Trenfield et al., 2018). Among these medical and pharmaceutical industries, orthopedic and dental applications are favorable to embrace the 3D printing technology (MarketsandMarkets, 2019). It is related to the demand for the patient-specific design and fabrication of the final devices (such as joint prosthesis, surgical guides, and dental restorations) (Eltorai et al., 2015; Tahayeri et al., 2018). Personalized devices manufactured preoperationally are benefited for the efficiency and accuracy (Konta et al., 2017). For medical education and surgical planning, 3D anatomical models are printed subtly with microscopic anatomy structures (Mukherjee et al. , 2017; Ganguli et al., 2018). Tissue and organ printing is an emerging field that mainly focused on regenerative medicine and tissue engineering by both academy and industry (Murphy and Atala, 2014). Based on it, preclinical patient-specific disease models are used for drug testings and screenings. 3D printing technology is merging with traditional pharmaceuticals for the development of dose-customized drugs (Norman et al., 2017).

In this review, recent techniques and applications of 3D printing in medical materials are well summarized. Common AM techniques and printable materials are presented for better understanding of their potential, limitations, and applications. Medical applications including tissue engineering, anatomical models, apparatus, and instruments with 3D printing technology are also provided and summarized. We finally demonstrate our concluding remarks and future outlook on 3D printing in medical materials (Figure 1).

Figure 1 Progressive 3d printing technology and its application in medical materials. Chart showing the application area (yellow boxes) with corresponding products (blue boxes) and primary 3D printing techniques (green boxes).

Current am Technologies and Printable Materials

There are about two dozen AM techniques, among which only some techniques are widely applied in medical industry. The main reason is the specific fabrication process and raw material to meet the high-quality requirements for medical devices. Four common AM techniques are powder-based printing (Brunello et al., 2016), vat polymerization-based printing (Stefaniak et al., 2019), droplet-based printing (Graham et al., 2017), and extrusion-based printing (Taylor et al., 2018).

Powder-Based Printing

Powder-based 3D printing is a promising technique with excellent ability for customized fabrication with a variety of external shapes, internal structures, and porosities. There are four common powder-based printing techniques: selective laser sintering (SLS), selective laser melting (SLM), direct metal laser sintering (DMLS), and electron beam melting (EBM) (Figure 2) (Brunello et al. , 2016). Every technique is based on localized heating to generate melted metallic powder, which would be used to fabricate the customized products. There are obvious differences in both printing process and product characters among these four powder-based printing techniques. For SLS and DMLS, powder particles are bounded with laser instead of spray solution. In the printing process, the laser draws specific patterns on one layer of the powder bed (Fina et al., 2017). The roller in the printer distributes a new layer of powder onto the surface once the printing of the previous layer is completed. After being built layer-by-layer, printed objects are collected underneath the powder bed. As a specific kind of SLS, DMLS utilizes metal exclusively. Different from sintering techniques, SLM and EBM fully melt powder with laser and electron beam respectively (Wysocki et al., 2018). For the work of electron beam, the powder bed in the EBM printer maintains high working temperature (> 870 K). It directly affects the quality of the fabrication especially in the details of microstructure. Comparatively, products printed with SLM maintain higher tribological, mechanical, and corrosion properties. With the differences between sintering and melting, the surfaces of products printed with sintering techniques (SLS and DMLS) are rough as powders are not completely melted.

Figure 2 Printing process of powder-based printing and related products. (A) Schematic diagram. (B) Products manufactured by powder-based printing method. Reproduced, with permission, from (Brunello et al., 2016).

Although the sintering techniques produce products with rough surfaces, they can process with a large variety of materials including plastic powder, ceramic powder, and metal alloys. As the high working temperature, material with volatile constituents (Mg, Zn, Bi, etc.) are not feasible for EBM, while SLM can treat a much wider spectrum of metallic alloys including Ti-based, Al-based, Fe-based, Ni-based, Cu-based, Co-based, and their composites. However, the melting process brings a big advantage that it can produce fully dense parts without post-treatment steps such as infiltration or thermal process.

Vat Polymerization-Based Printing

Vat-polymerization based printing technique is based on light curing resin material and light selective hardening polymerization molding. It is widely used for fabricating complex devices with functional parts such as valves, lenses and fluidic interconnects (Carve and Wlodkowic, 2018). In the process, a vat of photosensitive polymer resin is selectively exposed to a specifically controlled beam of leaser or light (Credi et al., 2016; Credi et al., 2018). The polymer is polymerized after spatially localized irradiation to fabricate the specific constructions (Credi et al., 2016; Wang et al., 2018a). Common process includes digital light processing (DLP), stereolithography (SLA), and multiphoton polymerization (MPP) (Figure 3) (Carve and Wlodkowic, 2018). SLA was the first AM technology applied in medicine in 1994 (Dittmann et al. , 1994). A spot laser irradiates the resin localized in a single x-y direction in SLA (Zanchetta et al., 2016), whereas a digital illuminant irradiates the whole x-y plan in DLP (Osman et al., 2017). For both SLA and DLP, the print platform moves parallelly to the z-axis while the final product is fabricated layer-by-layer (Zanchetta et al., 2016; Osman et al., 2017). Differently in MPP, the photosensitive polymer resin is irradiated by a femtosecond laser beam thoroughly in multi directions, resulting that it is not a layer-by-layer technology (Wollhofen et al., 2018). Products printed with vat polymerization technology need to be exposed to light after printing to enhance stability (Credi et al., 2016; Carve and Wlodkowic, 2018).

Figure 3 Polymer scaffold fabricated with SLA approach. (A) Schematic diagram. (B) Products manufactured by vat-polymerization based printing method. Reproduced, with permission, from (Mondschein et al. , 2017).

Droplet-Based Printing

Material jetting technology is a process where droplets of liquid materials are ejected and polymerized throughout hundreds of jets. The polymerization only occurs selectively by directed UV for designed structures (Revilla-Leon and Ozcan, 2019). Material jetting technology includes aerosol jet printing (AJP), binder jet printing (BJP), and poly jet printing (PJP) (Figure 4). During AJP, composite in aerosol suspension droplets is carried via N₂ gas and ejected onto the substrate layer by layer (Yuan et al., 2017). Multi materials including metals, polymers, and ceramics can be used in AJP with a low printing temperature, which is benefit for biomanufacturing (Mahajan et al., 2013). Binder jet printing (BJP) is similar with SLS except that BJP do not need thermoplastic excipient (Hong et al., 2016). The binder in BJP should meet specific ranges of surface tension (35–40 mJ/N) and viscosity (5–20 Pa·s) (Kim D. H. et al., 2018). In PJP, polymer resin drops are cured by UV light immediately without time consuming postprocessing (Revilla-Leon and Ozcan, 2019). With high resolution, PJP is capable of printing refined structures (Carve and Wlodkowic, 2018).

Figure 4 3D printing of droplet-based printing. (A) Schematic diagram of droplet-based cell printing. (B) Bright-field micrographs of patterned cell junctions containing two cell types. (C) Confocal fluorescence micrographs of cell constructs printed under oil. Reproduced, with permission, from (Brunello et al., 2016).

Extrusion-Based Printing

Extrusion-based printing was firstly developed by S. Scott Crump in 1988, commonly referred as fused deposition modeling (FDM) or fused filament fabrication (FFF) (Placone and Engler, 2018). FDM is a mature technology based on the extrusion of thermoplastic or composite materials drawn through the hot extrusion head (with one/multiple extrusion nozzles) (Paxton et al. , 2017). Fused materials were deposited layer by layer with the horizontal and vertical movement of nozzles controlled by numerically-controlled machine tool (Ozbolat and Hospodiuk, 2016). Extrusion-based printing widely applied in metal printing, polymer printing, and bioprinting (Figure 5) (Ning and Chen, 2017). The printing techniques have been recently developed to precision extrusion deposition (PED) (Fedore et al., 2017), precise extrusion manufacturing (PEM) (Jamroz et al., 2018), and multiple heads deposition extrusion (MHDS) (Serex et al., 2018). Multiple bioprinting applications in vascular models, soft-tissue models, and bone models manufactured with extrusion-based printing technology have been well-developed in recent years (Ahlfeld et al., 2017; Paxton et al., 2017; Ahlfeld et al., 2018). One major advantage of its bioprinting application is that the hydrogels of extrusion-based printing is capable to fabricate products with high cell density (> 1 × 10⁶ cells ml⁻¹) (Petta et al. , 2018; Taylor et al., 2018; Chen et al., 2019).

Figure 5 3D printing of extrusion-based multi-layer printing. (A) Schematic diagram of extrusion-based printing. (B) Multi materials printed with two cell types. (C–F) Available complex organs printed with extrusion-based printing techniques. Reproduced, with permission, from (Placone and Engler, 2018).

Applications in Medical Materials

AM technologies have been widely applied in medical materials, especially in tissue engineering, medical models, medical instruments, and drug formulations. A variety of printing technologies and products have lightened the broad market of medical and chemical applications of 3D printing.

Functional Biomaterials for Tissue Engineering

Tissue engineering with 3D printing has been focused on two parts, functional biomaterials for tissue implantation and tissue models for disease studies. In this section, functional biomaterials manufactured with AM technologies would be the focus. Tissue scaffolds are important component of 3D printing tissue engineering as they can provide structural supports for cell attachment, proliferation and migration (Figure 6). Tissue engineering scaffolds and basic medical scaffolds are considered different especially in biological activity and application purposes (Yang et al., 2018). Good bioactivity, excellent biocompatibility, and appropriate mechanical property are three basic requirements for an ideal tissue engineering scaffold. While basic medical scaffolds are usually applied for filling tissue coloboma or fixation without requirement for bioactivity. Implantable tissue engineering scaffolds are required to be degradable where scaffolds would be replaced by palingenetic tissues (Wang et al., 2018b). To induce tissue or bone growth inside the scaffolds, traditional procedures including molding, freeze drying, and electrospinning have been applied in the manufacture. However, none of the traditional procedures can fabricate scaffolds with customized mechanics, architecture and porosity. With the development of AM, scaffolds with high resolution, customized design, and high porosity have been successful in medical applications.

Figure 6 Functional biomaterials and related printing technique. (A) Schematic of a 3D printing platform for performing a water-based biological scaffold. (B) Appearance of 3D printed brackets in various shapes and sizes. Reproduced, with permission, from (Hung et al., 2016).

Tissue engineering scaffolds are fabricated in two major methods, printing with cells mixed in ink or gel and seeding cells onto scaffolds post printing. The most common methods applied in scaffolds fabrication are vat polymerization, SLS, BJ, and FDM. Inkjet printing and extrusion-based printing are the two popular bioprinting technologies, while bio-scaffolds are fabricated based on or without scaffolds. For bioprinting techniques based on scaffolds, hydrogels or polymers laden with cells are cured with AJP, BJP, PJP, and vat polymerization. For bioprinting techniques without scaffolds, hydrogels filled with high cell density (> 1 × 10⁶ cells ml⁻¹) are applied directly relying on cell-cell interactions. Cells in such density need to fuse and mature in the bioreactor for a period of time.

Only a few companies have launched commercial tissue engineering scaffolds. Organogenesis Inc, one of the world's most famous FDA-approved 3D printed medical device supplier, introduced their GINTUIT™, a tissue engineering product approved in 2012 for oral soft tissue repair and regeneration. It is a commercialized cell and gene therapy product combined fibroblasts and keratinocytes in bovine collagen. In 2016, another famous supplier, Stryker released the product Tritanium^® LP, a titanium lumber posterior cage. The lumber cage is fabricated with abundant porous by DMLS technology with titanium alloy. The inner porous are helpful for blood vessel and bone growth inside the lumber cage.

With widespread concerns from various industries, bioprinting and tissue engineering have made significant progress and wide applications. Applications covered profuse tissues including tooth, bone, cartilage, ear, blood vessel, liver, kidney, and myocardium (Zhu et al., 2019). In 2017, Monica M. Laronda et al. from Northwestern university claimed successful fabrication of a bioprosthetic ovary created using 3D printed microporous scaffolds restoring ovarian function in sterilized mice (Laronda et al., 2017). Recently, Byoung Soo Kim and his colleges developed human skin with PJP 3D printing system (Ahn et al., 2016). This printed skin showed favorable biological characteristics, including stable dermis and epidermal layers. Manufactured skin substitutes can significantly improve skin healing of the wound area.

Anatomical and Pharmacological Models

To date, 3D printed tissue models play a significant role in the studies of mechanism of disease, pharmacological testing for new drugs, effectiveness of preclinical therapy, and anatomical structures of complicated organs (Figures 7 and 8). For these studies, conventional methods take plenty of mice and other experiment animals for building animal models. Typically, patient derived xenograft (PDX) models for medical studies always cost a large amount of immunodeficient mice to engraft disease cells. This kind of process takes a great mass of time and money. To overcome the disadvantage, tissue models were developed, firstly by traditional fabrication technologies without 3D printing. However, products by traditional methods revealed inaccurate models with unrealistic tissue status. With the application of 3D printing, biomimetic tissue models with high resolution are fabricated more efficiently at a lower cost than in the past. In this part, 3D printed tissue models of skin, liver, and tumor would be discussed.

Figure 7 Anatomical 3D models of heart in normal and pathological state. (A) Normal anatomical 3D printed heart model. (B) Tetralogy of Fallot anatomical 3D printed heart model. Reproduced, with permission, from (Bartel et al., 2018).

Figure 8 Applications and limitations of 3D organ models in pharmacological research. Reproduced, with permission, from (Weinhart et al., 2019).

The liver is a complex organ with multiple functions which have biotransformation effects on many non-nutritive substances (such as various drugs, poisons, and certain metabolites) in the body. They are completely decomposed by metabolism or excreted in the original form. With highly sensitive to drug toxicity, liver tissue engineering models were developed to take drug screening and testing. Reproducing the complex structures with 3D printing technology is the basic step for mimicking hepatic functions. To date, multiple fabrications of liver tissue models were accomplished with several 3D printing technologies. Ho-Joon Lee et al. developed multicellular 3D liver with multi-functions encapsulated in hybrid hydrogel (Lee et al., 2017). HepaRG cells alone or with supporting cells were encapsulated in semi-IPNs (hydrogel) and printed with vat polymerization technology. Fabricated 3D liver model was verified to be functional maturation with a dynamic 3D microenvironment, which is important for disease modeling and drug testing. Huanhuan Joyce Chen et al. fabricated a 3D scaffold co-cultured with human intestinal cells (hIECs) and liver cells to mimic a two-organ body-on-chip situation (Chen et al., 2018). The hIECs and liver cells in this scaffold were verified to maintain high viability and differentiable. While hIECs differentiated into human gastrointestinal cells, liver cells developed into lobule-like structures. Two organs on chip 3D model significantly improved the studies on human response and Inter-organ relationships. The two 3D liver models above were well fabricated and suitable for short-term studies. To realize long-term studies with functional liver tissue models, Hassan Rashidi et al. developed a stable 3D liver tissue model with certain function, which is testified for 1 year (Rashidi et al., 2018). Mimicking realistic conditions, hexagonal scaffolds were fabricated with polycaprolactone embraced with self‐aggregated pluripotent stem cells (PSCs) spheroids. Embedding with PSCs-loaded implants, two mice models of tyrosinemia were claimed to heal without any infection. Emerging 3D liver tissue models are helping solving problems in an efficient and cost-effective way that we cannot imagine before.

As one of the largest organs in human body, skin covers the whole-body surface and plays an important role in protecting, excreting, regulating body temperature, and feeling external stimuli. For patients with extensive skin wounds, clinical therapies would be complicated and important. To test the efficacy and safety of treatment, skin tissue models reveal an irreplaceable role. Byoung Soo Kim et al. fabricated a 3D printing skin tissue model with skin-derived extracellular matrix (S-dECM) bioink (Kim B. S. et al., 2018). Embraced in vivo with endothelial progenitor cells (EPCs) and adipose-derived stem cells (ASCs), 3D printing skin model accelerated wound healing especially in reepithelization and neovascularization. John W. Wills et al. adapted nanoparticles in 3D reconstructed skin micronucleus (RSMN) assay (Wills et al., 2016). After normalizing the dose between the total nanoparticle mass and the cell number between 2D/3D assays, the 3D dose response was compared to the 2D micronucleus assay. Due to the protective properties of the 3D cell microstructure and the mixed barrier effect, tested silica particles revealed no (gene) toxicity for live cells in the 3D model comparing to the 2D assay. Plenty results suggested 3D skin model can more accurately reflect the toxicity of nanoparticle drugs on human skin function than traditional methods.

Tumor is a new pathological organism formed by the proliferation of local tissue cells under the action of various tumorigenic factors, and has an extremely complex microenvironment and microstructure. It is significant to mimic in vivo tumor environment with stroma and micro structures for the accuracy of testing new theories and therapies (Costa et al., 2016). Jizhao Li et al. developed a 3D cell model with human lung cancer A549 cells applied in scaffolds fabricated with silk fibroin protein and chitosan (Li et al., 2018). By resembling pathological conditions, the 3D tumor model provide a valuable biomaterial platform for in-vitro test of antitumor drugs for non-small cell lung cancer. Yu Zhao et al. fabricated a 3D in vitro cervical tumor model with 3D printing of Hela cells in hydrogel grid structure by a layer-by-layer fashion (Zhao et al., 2014). With higher proliferation rate and matrix metalloproteinase protein expression, 3D cervical model fabricated with novel 3D printing technology is helping cervical tumor studies. Therefore, with the development of 3D printing tissue models, it is credible for the promising future that studies will be done more efficiently without sacrifices from experimental animals.

Medical Apparatus and Instruments

AM is a promising and novel technology for the production of medical apparatus and instruments comparing with traditional manufacturing techniques. Directed by patient's clinical images, custom-designed medical apparatus and surgical guides are fabricated efficiently and accurately. It brings anatomically fit to patients and surgical safety to surgeons. Besides, AM is capable of manufacturing complex microstructures which are not possible for conventional techniques (Figure 9). With these advantages, AM allows fast production with high resolution, few leftover material and low costs. In this section, discussion is focused on (i) prostheses and implants and (Heidari Keshel et al., 2016) auxiliary medical equipment.

Figure 9 Medical apparatus and instruments by 3D printing. (A) 3D printed guide template for surgery simulation. (B, C) 3D printed titanium apparatus for cervical spine and pelvic surgery respectively. Reproduced, with permission, from (Xu et al., 2016; Wei et al., 2017; Nie et al., 2019).

Medical implants and orthoses/prostheses (O&P) have been fabricated with traditional methods for decades. As with long term application, conservative implants revealed problems including anatomical mismatching, incompetent binding strength and initial stability, poor bone ingrowth and long-term stability, and low cost-efficiency (Wang et al., 2019). All these problems have been solved with AM technology, which is capable to fabricate implants with proper surface and mechanical properties. Powder-based 3D printing techniques (SLM, SLS, and EBM) are widely applied in implants and O&P manufacturing as they are compatible with a wide range of printing materials, such as titanium alloy, zinc alloy, cobalt–chrome alloy, and polyetheretherketone (PEEK). With outstanding mechanical properties and biocompatibility, 3D printed implants have been applied in plenty of surgical majors, including tracheobronchial (Zopf et al., 2014; Han et al., 2018), dentofacial, cardiovascular, orthopedic, and spine. For severe tracheobronchomalacia patients, a 3D printed self-expandable, metallic tracheobronchial stent fabricated with SLS technology was implanted into patient's collapse bronchus and rebuilt airway efficiently (Han et al., 2018). The printing technology offer a great opportunity of reconstruction and support for tracheobronchial diseases, which was difficult for conservative implants to be fabricated anatomically fitted. Besides self-expandable stent, a 3D printed bioresorbable stent was fabricated with SLS technique (Zopf et al. , 2014). Printed bioresorbable stents were embedded into severe tracheobronchomalacia pig model, significant resolution of symptoms was observed. The stent was resorbed over time and was considered as a “4D” functional material. In maxillofacial and craniofacial surgeries, complex anatomy structures and irregular shapes of defects are the two most severe challenges. Conventionally, craniofacial prostheses are fabricated with hand-curved wax model for the anatomic defect with low precision. With 3D printing techniques, patient-customized prostheses are fabricated with guidance from CT or MRI images in which details for defects are well recorded. Kyle K et al. demonstrated the first application case of 3D printing in complex fetal craniofacial anomalies and perinatal management (VanKoevering et al., 2015). Researchers from Saint Louis University School of Medicine reviewed 315 patients who underwent 3D printing assisted maxillofacial and craniofacial surgeries (Jacobs and Lin, 2017). Fabrications with 3D printing techniques were mainly focused on contour models, surgical guides, splints, and implants. These objects were mainly fabricated in factory and laboratory with an average time and cost of 18.9 h and $1,353.31 respectively. Without lab or proficiency with printing software, low-cost 3D maxillofacial models could be fabricated with a cost of only $90 (Legocki et al., 2017). While commercial models can be manufactured with serializable materials and advanced virtual planning, this low-cost method can generate models with high-fidelity as educational and surgical planning tools. Cardiac diseases have been widely studied with the assistance of 3D printing technology as it offers high-resolution reduction of pathological status (Vukicevic et al., 2017). Variety of printing techniques including material jetting (Olivieri et al., 2015; Lind et al., 2017; Lau et al., 2018; Su et al., 2018), FDM (Mahmood et al., 2015; Son et al., 2015), SLS, and SLA have been applied in the studies of structural heart disease, congenital heart disease, coronary arteries, and systemic vasculature. Benefiting from 3D printing techniques, advanced visualization (Mahmood et al., 2015; Olivieri et al., 2015), diagnosis (Son et al., 2015), planning of surgeries, interventions (Lind et al., 2017), education (Lau et al., 2018; Su et al., 2018), and researches (Mahmood et al., 2015; Lind et al., 2017) in cardiovascular diseases are developing rapidly.

Conclusion

This paper reviews the advancements of 3D printing technologies applied in medical materials in recent years. With the superiority of patient-specific designs, high complexity, favorable productivity, and cost-effective manufacturing methods, 3D printing has been becoming widely accepted manufacturing technologies in the medical applications. The main applications of 3D printing in medicine include tissue engineering models, anatomical models, pharmacological designs and validation models, medical apparatus and instruments. Orthopedics is one of the most advanced fields that integrate 3D printing to produce end-use products such as restorations, spine models, and surgical navigation boards. Orthopedics is a pioneer in medical devices. Currently, there are many multiple 3D printed medical products on the market, including implantable craniofacial implants, acetabular cups, knee implants, spinal cages, and surgical instruments. In addition, about 99% of hearing aid housings are custom made through 3D printing. Pre-surgery printed anatomical models have revolutionized the way surgeons and medical students were trained for surgery. To date, researchers have printed about 16 different types of tissues, providing tissue models for high-throughput screening for new drugs. It is believed that 3D printing is affecting clinical and related basic research in an increasingly broader manner.

Author Contributions

DF and YL contributed equally to this reviewed manuscript. XW, YT and ZL conceived and designed the content of the manuscript. DF, YL and XW collected the researched literatures, arranged the outline of collected documents and wrote the articles. TZ, QW, HC, and WL made important suggestions and helped revising the manuscript. All authors reviewed and commented on the entire manuscript.

Funding

This research was funded by the Ministry of Science and Technology of China (2016YFB1101501 and 2018YFE0104200) and National Natural Science Foundation of China (NSFC, 51973226).

Conflict of Interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

The handling editor and reviewer JD declared their involvement as co-editors in the Research Topic, and confirm the absence of any other collaboration.

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What is 3D Printing? - Technology Definition and Types

3D printing, also known as additive manufacturing, is a method of creating a three dimensional object layer-by-layer using a computer created design.

3D printing is an additive process whereby layers of material are built up to create a 3D part. This is the opposite of subtractive manufacturing processes, where a final design is cut from a larger block of material. As a result, 3D printing creates less material wastage.

This article is one of a series of TWI frequently asked questions (FAQs).

3D printing is also perfectly suited to the creation of complex, bespoke items, making it ideal for rapid prototyping.

What materials can be used?
History
Technologies
Process types
How long does it take?
Advantages and disadvantages
What is an STL file?
Industries
Services
FAQs

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There are a variety of 3D printing materials, including thermoplastics such as acrylonitrile butadiene styrene (ABS), metals (including powders), resins and ceramics.

Who Invented 3D Printing?

The earliest 3D printing manufacturing equipment was developed by Hideo Kodama of the Nagoya Municipal Industrial Research Institute, when he invented two additive methods for fabricating 3D models.

When was 3D Printing Invented?

Building on Ralf Baker's work in the 1920s for making decorative articles (patent US423647A), Hideo Kodama's early work in laser cured resin rapid prototyping was completed in 1981. His invention was expanded upon over the next three decades, with the introduction of stereolithography in 1984. Chuck Hull of 3D Systems invented the first 3D printer in 1987, which used the stereolithography process. This was followed by developments such as selective laser sintering and selective laser melting, among others. Other expensive 3D printing systems were developed in the 1990s-2000s, although the cost of these dropped dramatically when the patents expired in 2009, opening up the technology for more users.

There are three broad types of 3D printing technology; sintering, melting, and stereolithography.

Sintering is a technology where the material is heated, but not to the point of melting, to create high resolution items. Metal powder is used for direct metal laser sintering while thermoplastic powders are used for selective laser sintering.
Melting methods of 3D printing include powder bed fusion, electron beam melting and direct energy deposition, these use lasers, electric arcs or electron beams to print objects by melting the materials together at high temperatures.
Stereolithography utilises photopolymerization to create parts. This technology uses the correct light source to interact with the material in a selective manner to cure and solidify a cross section of the object in thin layers.

Types of 3D printing

3D printing, also known as additive manufacturing, processes have been categorised into seven groups by ISO/ASTM 52900 additive manufacturing - general principles - terminology. All forms of 3D printing fall into one of the following types:

Binder Jetting
Direct Energy Deposition
Material Extrusion
Material Jetting
Powder Bed Fusion
Sheet Lamination
VAT Polymerization

Binder Jetting

Binder jetting deposits a thin layer of powered material, for example metal, polymer sand or ceramic, onto the build platform, after which drops of adhesive are deposited by a print head to bind the particles together. This builds the part layer by layer and once this is complete post processing may be necessary to finish the build. As examples of post processing, metal parts may be thermally sintered or infiltrated with a low melting point metal such as bronze, while full-colour polymer or ceramic parts may be saturated with cyanoacrylate adhesive.

Binder jetting can be used for a variety of applications including 3D metal printing, full colour prototypes and large scale ceramic moulds.

Direct Energy Deposition

Direct energy depositioning uses focussed thermal energy such as an electric arc, laser or electron beam to fuse wire or powder feedstock as it is deposited. The process is traversed horizontally to build a layer, and layers are stacked vertically to create a part.

This process can be used with a variety of materials, including metals, ceramics and polymers.

Material Extrusion

Material extrusion or fused deposition modelling (FDM) uses a spool of filament which is fed to an extrusion head with a heated nozzle. The extrusion head heats, softens and lays down the heated material at set locations, where it cools to create a layer of material, the build platform then moves down ready for the next layer.

This process is cost-effective and has short lead times but also has a low dimensional accuracy and often requires post processing to create a smooth finish. This process also tends to create anisotropic parts, meaning that they are weaker in one direction and therefore unsuitable for critical applications.

Material Jetting

Material jetting works in a similar manner to inkjet printing except, rather than laying down ink on a page, this process deposits layers of liquid material from one or more print heads. The layers are then cured before the process begins again for the next layer. Material jetting requires the use of support structures but these can be made from a water-soluble material that can be washed away once the build is complete.

A precise process, material jetting is one of the most expensive 3D printing methods, and the parts tend to be brittle and will degrade over time. However, this process allows for the creation of full-colour parts in a variety of materials.

Powder Bed Fusion

Powder bed fusion (PBF) is a process in which thermal energy (such as a laser or electron beam) selectively fuses areas of a powder bed to form layer, and layers are built upon each other to create a part. One thing to note is that PBF covers both sintering and melting processes. The basic method of operation of all powder bed systems is the same: a recoating blade or roller deposits a thin layer of the powder onto the build platform, the powder bed surface is then scanned with a heat source which selectively heats the particles to bind them together. Once a layer or cross-section has been scanned by the heat source, the platform moves down to allow the process to begin again on the next layer. The final result is a volume containing one or more fused parts surrounded by unaffected powder. When the build is complete, the bed is fully raised to allow the parts to be removed from the unaffected powder and any required post processing to begin.

Selective laser sintering (SLS) is often used for manufacture of polymer parts and is good for prototypes or functional parts due to the properties produced, while the lack of support structures (the powder bed acts as a support) allows for the creation of pieces with complex geometries. The parts produced may have a grainy surface and inner porosity, meaning there is often a need for post processing.

Direct metal laser sintering (DMLS), selective laser melting (SLM) and electron beam powder bed fusion (EBPBF) are similar to SLS, except these processes create parts from metal, using a laser to bond powder particles together layer-by-layer. While SLM fully melts the metal particles, DMLS only heats them to the point of fusion whereby they join on a molecular level. Both SLM and DMLS require support structures due to the high heat inputs required by the process. These support structures are then removed in post processing ether manually or via CNC machining. Finally, the parts may be thermally treated to remove residual stresses.

Both DMLS and SLM produce parts with excellent physical properties - often stronger than the conventional metal itself, and good surface finishes. They can be used with metal superalloys and sometimes ceramics which are difficult to process by other means. However, these processes can be expensive and the size of the produced parts is limited by the volume of the 3D printing system used.

Sheet Lamination

Sheet lamination can be split into two different technologies, laminated object manufacturing (LOM) and ultrasonic additive manufacturing (UAM). LOM uses alternate layers of material and adhesive to create items with visual and aesthetic appeal, while UAM joins thin sheets of metal via ultrasonic welding. UAM is a low temperature, low energy process that can be used with aluminium, stainless steel and titanium.

VAT Photopolymerization

VAT photopolymerization can be broken down into two techniques; stereolithography (SLA) and digital light processing (DLP). These processes both create parts layer-by-layer through the use of a light to selectively cure liquid resin in a vat. SLA uses a single point laser or UV source for the curing process, while DLP flashes a single image of each full layer onto the surface of the vat. Parts need to be cleaned of excess resin after printing and then exposed to a light source to improve the strength of the pieces. Any support structures will also need to be removed and additional post-processing can be used to create a higher quality finish.

Ideal for parts with a high level of dimensional accuracy, these processes can create intricate details with a smooth finish, making them perfect for prototype production. However, as the parts are more brittle than fused deposition modelling (FDM) they are less suited to functional prototypes. Also, these parts are not suitable for outdoor use as the colour and mechanical properties may degrade when exposed to UV light from the sun. The required support structures can also leave blemishes that need post processing to remove.

The printing time depends on a number of factors, including the size of the part and the settings used for printing. The quality of the finished part is also important when determining printing time as higher quality items take longer to produce. 3D printing can take anything from a few minutes to several hours or days - speed, resolution and the volume of material are all important factors here.

The advantages of 3D printing include:

Bespoke, cost-effective creation of complex geometries:
This technology allows for the easy creation of bespoke geometric parts where added complexity comes at no extra cost. In some instances, 3D printing is cheaper than subtractive production methods as no extra material is used.
Affordable start-up costs:
Since no moulds are required, the costs associated with this manufacturing process are relatively low. The cost of a part is directly related to the amount of material used, the time taken to build the part and any post processing that may be required.
Completely customisable:
Because the process is based upon computer aided designs (CAD), any product alterations are easy to make without impacting the manufacturing cost.
Ideal for rapid prototyping:
Because the technology allows for small batches and in-house production, this process is ideal for prototyping, which means that products can be created faster than with more traditional manufacturing techniques, and without the reliance on external supply chains.
Allows for the creation of parts with specific properties:
Although plastics and metals are the most common materials used in 3D printing, there is also scope for creating parts from specially tailored materials with desired properties. So, for example, parts can be created with high heat resistance, water repellency or higher strengths for specific applications.

The disadvantages of 3D printing include:

Can have a lower strength than with traditional manufacture:
While some parts, such as those made from metal, have excellent mechanical properties, many other 3D printed parts are more brittle than those created by traditional manufacturing techniques. This is because the parts are built up layer-by-layer, which reduces the strength by between 10 and 50%.
Increased cost at high volume:
Large production runs are more expensive with 3D printing as economies of scale do not impact this process as they do with other traditional methods. Estimates suggest that when making a direct comparison for identical parts, 3D printing is less cost effective than CNC machining or injection moulding in excess of 100 units, provided the parts can be manufactured by conventional means.
Limitations in accuracy:
The accuracy of a printed part depends on the type of machine and/or process used. Some desktop printers have lower tolerances than other printers, meaning that the final parts may slightly differ from the designs. While this can be fixed with post-processing, it must be considered that 3D printed parts may not always be exact.
Post-processing requirements:
Most 3D printed parts require some form of post-processing. This may be sanding or smoothing to create a required finish, the removal of support struts which allow the materials to be built up into the designated shape, heat treatment to achieve specific material properties or final machining.

An STL file is a simple, portable format used by computer aided design (CAD) systems to define the solid geometry for 3D printable parts. An STL file provides the input information for 3D printing by modelling the surfaces of the object as triangles that share edges and vertices with other neighbouring triangles for the build platform. The resolution of the STL file impacts the quality of the 3D printed parts - if the file resolution is too high the triangle may overlap, if it is too low the model will have gaps, making it unprintable. Many 3D printers require an STL file to print from, however these files can be created in most CAD programs.

Due to the versatility of the process, 3D printing has applications across a range of industries, for example:

Aerospace

3D printing is used across the aerospace (and astrospace) industry due to the ability to create light, yet geometrically complex parts, such as blisks. Rather than building a part from several components, 3D printing allows for an item to be created as one whole component, reducing lead times and material wastage.

Automotive

The automotive industry has embraced 3D printing due to the inherent weight and cost reductions. It also allows for rapid prototyping of new or bespoke parts for test or small-scale manufacture. So, for example, if a particular part is no longer available, it can be produced as part of a small, bespoke run, including the manufacture of spare parts. Alternatively, items or fixtures can be printed overnight and are ready for testing ahead of a larger manufacturing run.

Medical

The medical sector has found uses for 3D printing in the creation of made-to-measure implants and devices. For example, hearing aids can be created quickly from a digital file that is matched to a scan of the patient's body. 3D printing can also dramatically reduce costs and production times.

Rail

The rail industry has found a number of applications for 3D printing, including the creation of customised parts, such as arm rests for drivers and housing covers for train couplings. Bespoke parts are just one application for the rail industry, which has also used the process to repair worn rails.

Robotics

The speed of manufacture, design freedom, and ease of design customisation make 3D printing perfectly suited to the robotics industry. This includes work to create bespoke exoskeletons and agile robots with improved agility and efficiency.

TWI has one of the most definitive ranges of 3D Printing services, including selective laser melting, laser deposition, wire and arc additive manufacturing, wire and electron beam additive manufacturing and EB powder bed fusion small-scale prototyping, and more.

Additive Manufacturing

TWI provides companies with support covering every aspect of metal additive manufacturing (AM), from simple feasibility and fabrication projects to full adoption and integration of metal AM systems.

Laser Metal Deposition

TWI has been developing LMD technology for the last ten years. For full details of our capabilities in this area, and to find out more about the process and the benefits it can bring to your business.

Selective Laser Melting

TWI has been developing selective laser melting technology for the last decade. Find out full details of our capabilities in this area and the benefits it can bring to your business.

Can 3D Printing be used for Mass Production?

While there have been great advances in 3D printing, it still struggles to match other manufacturing techniques for high volume production. Techniques such as injection moulding allow for much faster mass production of parts.

Where is 3D Printing Heading in the Future?

As 3D printing technology continues to improve it could democratise the manufacture of goods. With printers becoming faster, they will be able to work on larger scale production projects, while lowering the cost of 3D printing will help its use spread outside of industrial uses and into homes, schools and other settings.

Which 3D Printing Material is most Flexible?

Thermoplastic polyurethane (TPU) is commonly deemed to be the most flexible material available to the 3D printing industry. TPU possesses bendable and stretchy characteristics that many other filaments do not have.

Which 3D Printing Material is the Strongest?

Polycarbonate is seen as the strongest 3D printing material, with a tensile strength of 9,800 psi, compared to nylon, for example, with just 7,000 psi.

Why is 3D Printing Important?

3D printing is important for the many benefits it brings. It allows users to produce items that have geometries which are difficult or impossible for traditional methods to produce. It also allows users with a limited experience to edit designs and create bespoke, customised parts. On-demand 3D printing also saves on tooling costs and provides an advanced time-to-market. 3D printing is important for industries such as aerospace, where it can create lightweight yet complex parts, offering weight saving, the associated fuel reductions and a better environmental impact as a result. It is also important for the creation of prototypes that can advance industry.

Will 3D Printing Replace Traditional Manufacturing?

3D printing has the capability to disrupt traditional manufacturing through the democratisation of production along with the production of moulds, tools and other bespoke parts. However, challenges around mass production mean that 3D printing is unlikely to replace traditional manufacturing where high volume production of comparatively simple parts is required.

Are 3D Printing Fumes Dangerous?

3D printing fumes can be dangerous to your health as the process produces toxic filament fumes. These emissions are produced as the plastic filaments are melted to create the product layer-by-layer. However, correct procedures such as ensuring sufficient ventilation or using extractors can solve this issue.

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Miscellaneous
3d printer

Our society is already so accustomed to technology that it is becoming more and more difficult to surprise us. However, a few years ago, we could not even imagine that 3D printing would enter our lives, and it would become possible to print machine tools, equipment, various figures, houses, and in the future entire neighborhoods. Sounds like science fiction, but it's reality.

3D printing has only recently entered our lives, but we are already on the verge of a real 3D revolution. Every day, the scope of 3D printing is expanding. The demand for 3D printers is constantly growing.

So what is a 3D printer? This is a device that allows you to create physical objects based on their 3D model. A 3D printer prints an object in three planes at once from bottom to top. 3D printers work with completely different materials, but their main principle is the layer-by-layer creation of an object.

What is the main purpose of using 3D printers? First of all, it is necessary to reduce the cost of production. Now engineers do not need to look at hundreds of drawings, just look at a real 3D model. Such a model can be tested, and then a ready-made version can be created. But prototyping isn't everything. 3D printing is also needed for fast production. Unfortunately, the prices for such prototypes are still very high, but over time they will certainly go down.

What are 3D printers? At the moment, there are food, construction, military, medical and printers that self-reproduce themselves.

3D food printers target one type of food, i.e. they only make cakes or only pizza. This printer uses an edible base and edible ink. Such printers can easily print even hamburgers. Why is a food 3D printer such a rarity? Firstly, there are not enough programmers and special software, and secondly, semi-finished components are not widely distributed everywhere. Food 3D printers are divided into 2 large groups.

These printers use ready-made semi-finished products and fillers.
These printers themselves synthesize the necessary substances and dress them in any form.

Military 3D printers capable of making rocket motors. Also, such printers are capable of making ready-made weapons.

3D construction printer allows people to use their imagination, it is easy to create unusually shaped houses with it. In the future, these 3D printers will create truly unique and highly aesthetic works. Also, 3D printers will be very handy for building new homes in areas that have been hit by natural disasters.

Medical 3D printers are already very popular. They allow you to take into account the smallest individual structural features of a person and make any ideal implant. People are already actively printing prostheses, trying to make whole organs.

There are also printers that not only reproduce their details, but also print themselves in their entirety.

3d printer

3D printers

Content

Introduction 3

1 History of three -dimensional printers 5

2 technologies 3D print 8 9 9 9

2.1 Laser 3D printing 8

2.2 Inkjet 3D-printing 9

3 “Home” 3D printer 12

3.1 Reprap 12

3.2 Cupcake 13

4 Fields of use 3D print 16

Conclusion 18

Bibliographic bibliors LIST 20

INTRODUCTION

3D printer is a special output device 3D data. Unlike the usual printer that outputs two-dimensional information onto a sheet of paper, a 3D printer allows you to output three-dimensional information, i.e. create certain physical objects. At the core 3D printing technology is based on the principle of layered creating (growing) a solid model.

Advantages of such devices before the usual ways of creating models are high speed, simplicity and low cost. For example, in order to create a model manually it may take several weeks or even months, depending on on the complexity of the product. As a result costs rise significantly for development, the terms are increasing release of finished products. 3D printers allow you to completely get rid of from manual labor and create model of the future product for only several hours, while excluding the possibility of errors inherent in "human factor."

Generally, 3D printers are used for rapid prototyping and are used in a variety of areas. Working with real physical models provides many advantages those who use 3D printing technology. First of all, it is an opportunity evaluate the ergonomics of the future product, its functionality and collectability, as well as exclude the possibility hidden errors before product launch into a series. Thus, it is possible save a significant amount of financial money and time thanks to shortening the production cycle.

In addition, on the finished model, you can conduct various tests before the final product variant. Moreover, prototypes allow to carry out such tests, which are not recommended for on the finished sample. For example, Porsche used a transparent plastic transmission model 911 GTI for study oil flow during its development. At It should be noted that such a model can be done very quickly - but in our time high speed is very important.

However, prototypes are not everything. The next step is rapid production. Already, some 3D printing technologies allow you to craft finished items from various materials. It's perfect solution for small batch production, because the unified process makes it possible to make any detail configuration in a relatively short time.

Moreover, the ability to quickly creating the required number of training models makes it possible to solve many educational problems. Apart from of this 3D printing is widely applied in medicine to create layouts human internal organs, prostheses and implants. High interest cause and marketing aspects 3D printing. Thanks to her, you can increase quality of work with clients, demonstrating full-fledged prototypes products. This technology is also used in 3D advertising. Among the exotic use cases for 3D printing should be note the production of footwear. For now This service is intended for professional athletes. Foot of the future owner scanned by laser for creation digital model. Based on this information and "grown" shoes by layer-by-layer laser sintering. Thus, 3D printing is one of the most promising technologies, which will save huge amount of time and effort for engineers and designers.

Next, we will look at the history of creation 3D printing technologies, their types, areas of application, as well as prospects development.

1 HISTORY BUILDING 3D PRINTER

First applications of technology 3D printing dates back to the 1980s. Then 3D printers were bulky and extremely expensive, and the region their use is very limited, and the very term - 3D printing - has not yet been existed.

Ancestor of modern installations for the formation of 3D objects can be considered American Charles Halla, who at 1986 patented the world's first stereolithography machine (SLA). Of course, she was far from being be called a 3D printer, but the basic ideas layer-by-layer creation of three-dimensional figures were laid down in it. In the same year, Hull founded 3D Systems and developed the first commercial 3D instrument, it was called Stereolithography Apparatus. In 1988, a model was developed SLA-250, it became the first machine for wide circle of users.

Figure 1 - Charles Hull with a new version of his 3D device // 3D Systems

Another important "person" 3D printing is a Stratasys company and its founder Scott Crump, who together with his wife in 1990 became the author of one of 3D printing modeling methods fusing method.

Modern history of 3D printers began in 1993 when it was established Solidscape company for the production of inkjet predecessors of 3D printers. The expression "3D printing" originated in the famous Massachusetts Institute of Technology only at 1995, when two students - Jim Bredt and Tim Anderson modified "flat" inkjet printer so that he did not print images on paper, but into a special container and made them voluminous. Registered patent used Z Corporation (created by Bredt and Anderson) and ExOne. This technology is used and to this day in 3D printers produced by ZCorp. The technology is based on inkjet printing by head unit on gypsum-based powder. At the same time, three heads of such a Z-printer are responsible for the formation of the color of the future models, and the fourth contains a transparent adhesive that provides reliable layer-by-layer bonding of powder particles. This technology currently widely used for industrial 3D modeling though and is not without certain shortcomings. the main one being the low the strength of the model and the need for its processing after manufacturing.

The next evolution of 3D prototyping was the advent of photopolymer technology inkjet printing PolyJet. Its essence is in that the printer head applies layers a layer of photopolymer that hardens immediately under the influence of ultraviolet. This technology and the equipment is much cheaper, to also allows 3D printing not only models, but also finished products with very high accuracy. Printers manufactured under brand of PolyJet, are currently most affordable, and they are already can be attributed to the usual office equipment.

3D printing technology to the present time is developing very rapidly, and there are models that are already quite affordable for use in a small office and even at home. To these include 3D printers that perform fusing printing polymer. Of course, large models on such devices will be difficult to obtain, but to develop models of souvenir products or jewelry, as well as to solve various design tasks they can be use successfully.

2 TECH 3D PRINTING

3D printing can be carried out in different ways and using different materials, but at the heart of any of which lies the principle of layered creation (growing) a solid object. point in time there are two main layer growth technology, this is a laser and jet.

2.1 3D laser printing

The oldest and oldest - laser, including stereolithography (SLA), which allows you to create a three-dimensional model according to computer CAD drawings. She is and was invented at 1986 by Charles Hull. The principle of stereolithography is based on the photopolymer, which is in liquid state. When illuminated this polymer special ultraviolet it freezes with a beam, forming a very dense and rigid frame. Complete with laser 3D printer comes with a special program that cuts the desired computer 3D model on many layers of thickness about 0.1 mm. In addition, she translates each layer into a drawing, which is subsequently and starts to print. photopolymer poured in a thin layer, translucent, freezes, the next is superimposed on top layer that hardens again under ultraviolet beam. After repeating such actions, a ready-made prototype model is formed, after which it is washed and cleaned from excess polymer residues. On SLA printers can print relatively large parts sizes up to 75 cm in height. However, devices are very expensive and differ large size size with a rather big closet, they weigh about a ton, and cost around 150 thousand euros. Besides, Note also the low speed. playback - just a few millimeters in hour. Compensates for slow speed and great price high quality ultimate model, which also becomes very reliable and durable.

Faster and cheaper technique - laser technology sintering (SLS), where in the role of a blank material is no longer a photopolymer, and the powder is made of low-melting plastic. In a 3D printer working on such principle, the laser cuts out a section of the future details on the powder that is heated to the melting point and subsequently sintered. The procedure is then repeated - the next layer of powder is poured and the laser again burns out the next layer. This technology was invented in the middle 80s, at 1989 patented by Carl Deckard and is now used in the company's products DTM Corporation. Laser sintering allows get very high quality and durable models at a relatively high speed (about a few centimeters per hour plus warm-up and cool-down time). Of the main positive points to be noted the possibility of printing metal products. This happens through the use metal shavings that are "rolled" in the smallest polymer particles. Model, made from such a powder is placed in a special furnace, where the entire polymer burns out, and the metal shavings are fused. The result is a metal part made of a mixture of steel and bronze, finished to use. As a basis for such powder, ceramics can be used or glass, which allows you to create after baking procedure heat-resistant or chemical resistant model.

2.2 3D inkjet

3D inkjet very similar to the operation of a conventional printer, only instead of paint the nozzle is squeezed out some hot plastic on a chilled platform, this is the so-called Fused Deposition Modeling (FDM) technology. Drops very quickly harden and form one of the layers future three-dimensional model (as in the laser printing, the model is created layer by layer). NASA is even going to integrate such 3D printer in a spaceship, calculated for long expeditions. After all, the astronauts surely need some detail for repair or replacement, and similar printing the device is simply needed. Still compact 3D printer with several dozen kilogram of source material is much more compact full-scale mechanical workshop. There is a technology inkjet 3D printing and using polymer powder. Z Corporation actively promotes it, and in the last time very, very successfully. Special head injects on gypsum or starch powder adhesive base, which, when solidified forms one of the layers of the future model. The highlight of this technology is that dyes can be added to the glue substances and make the model not only three-dimensional, but also colorful. Printers that work according to this principle, are relatively a little - from 8 to 30 thousand dollars, which ten times less than the cost of laser analogues. ProMetal uses a similar 3D printing principle as Z Corporation, only instead of gypsum-based powder, metal crumb. Well, what's next for small - burn the resulting model in the oven and get the finished model. Below a summary table of the main technologies is given 3D printing.

Table 1 - 3D printing technologies

Technology name	How it works	Consumable
Laser Stereolithography (SLA)	The object is formed from a liquid photopolymer that hardens under the influence of laser radiation. laser radiation forms a current on the surface layer of the object being developed, after which, the object is immersed in a photopolymer for the thickness of one layer in order to the laser could begin to form the next layer.	Photopolymer resin

Table 1 continued

Selective laser sintering

(SLS)

Object formed from fusible powder material (plastic, metal) by its melting under the action of laser radiation. Powder material applied to the platform with a thin uniform layer, after which laser radiation forms on the surface the current layer of the developed object. Then the platform is lowered by a thickness one layer and applied again powdered material. this technology does not need supporting structures "hanging in the air" elements of the developed object, by filling voids with powder

Fusible polymer powder

Electron beam melting (EBM)

Same as SLS, but here an object is formed by melting metal powder by electron beam in vacuum.

Metal Powder

Directional Modeling (FDM)

The object is formed by layering molten filament from fusible worker material (plastic, metal, wax). Worker material is fed into the extrusion head, which extrudes a thin thread on a cooled platform molten material, forming a current layer of the developed object.

Abstract of 3d printing

Progressive 3D Printing Technology and Its Application in Medical Materials

Introduction

Current am Technologies and Printable Materials

Powder-Based Printing

Vat Polymerization-Based Printing

Droplet-Based Printing

Extrusion-Based Printing

Applications in Medical Materials

Functional Biomaterials for Tissue Engineering

Anatomical and Pharmacological Models

Medical Apparatus and Instruments

Conclusion

Author Contributions

Funding

Conflict of Interest

References

What is 3D Printing? - Technology Definition and Types

Contents

TWI

Who Invented 3D Printing?

When was 3D Printing Invented?

Types of 3D printing

Binder Jetting

Direct Energy Deposition

Material Extrusion

Material Jetting

Powder Bed Fusion

Sheet Lamination

VAT Photopolymerization

Aerospace

Automotive

Medical

Rail

Robotics

Additive Manufacturing

Laser Metal Deposition

Selective Laser Melting

Can 3D Printing be used for Mass Production?

Where is 3D Printing Heading in the Future?

Which 3D Printing Material is most Flexible?

Which 3D Printing Material is the Strongest?

Why is 3D Printing Important?

Will 3D Printing Replace Traditional Manufacturing?

Are 3D Printing Fumes Dangerous?

Related Frequently Asked Question (FAQs)

What are the Pros and Cons of 3D Printing?

How Long Does 3D Printing Take?

Can 3D Printing Use Metal?

What is Additive Manufacturing?

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3D printers

INTRODUCTION

1 HISTORY BUILDING 3D PRINTER

2 TECH 3D PRINTING

2.1 3D laser printing

2.2 3D inkjet

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