3D printing or Additive manufacturing is a process of making a three-dimensional solid object of virtually any shape from a digital model. 3D printing is achieved using an additive process, where successive layers of material are laid down in different shapes. 3D printing is also considered distinct from traditional machining techniques, which mostly rely on the removal of material by methods such as cutting or drilling (subtractiveprocesses).
A 3D printer is a limited type of industrial robot that is capable of carrying out an additive process under computer control.
While 3D printing technology has been around since the 1980s, it was not until the early 2010s that the printers became widely available commercially.The first working 3D printer was created in 1984 by Chuck Hull of 3D Systems Corp. Since the start of the 21st century there has been a large growth in the sales of these machines, and their price has dropped substantially. According to Wohlers Associates, a consultancy, the market for 3D printers and services was worth $2.2 billion worldwide in 2012, up 29% from 2011.
The 3D printing technology is used for both prototyping and distributed manufacturing with applications in architecture, construction (AEC), industrial design, automotive, aerospace, military, engineering, civil engineering, dental and medical industries, biotech (human tissue replacement), fashion, footwear, jewelry, eyewear, education, geographic information systems, food, and many other fields. One study has found that open source 3D printing could become a mass market item because domestic 3D printers can offset their capital costs by enabling consumers to avoid costs associated with purchasing common household objects.
General principles
3D Printable Models
3D printable models may be created with a computer aided design package or via 3D scanner. The manual modeling process of preparing geometric data for 3D computer graphics is similar to plastic arts such as sculpting. 3D scanning is a process of analyzing and collecting data of real object; its shape and appearance and builds digital, three dimensional models.
Both manual and automatic creation of 3D printable models is difficult for average consumers. This is why several 3D printing marketplaces have emerged over the last years. Among the most popular are Shapeways, Thingiverse and Threeding
Printing
To perform a print, the machine reads the design from an STL file and lays down successive layers of liquid, powder, paper or sheet material to build the model from a series of cross sections. These layers, which correspond to the virtual cross sections from the CAD model, are joined or automatically fused to create the final shape. The primary advantage of this technique is its ability to create almost any shape or geometric feature.
Printer resolution describes layer thickness and X-Y resolution in dpi (dots per inch), or micrometers. Typical layer thickness is around 100 µm (250 DPI), although some machines such as the Objet Connex series and 3D Systems' ProJet series can print layers as thin as 16 µm (1,600 DPI).[19] X-Y resolution is comparable to that of laser printers. The particles (3D dots) are around 50 to 100 µm (510 to 250 DPI) in diameter.
Construction of a model with contemporary methods can take anywhere from several hours to several days, depending on the method used and the size and complexity of the model. Additive systems can typically reduce this time to a few hours, although it varies widely depending on the type of machine used and the size and number of models being produced simultaneously.
Traditional techniques like injection molding can be less expensive for manufacturing polymer products in high quantities, but additive manufacturing can be faster, more flexible and less expensive when producing relatively small quantities of parts. 3D printers give designers and concept development teams the ability to produce parts and concept models using a desktop size printer.
Finishing
Though the printer-produced resolution is sufficient for many applications, printing a slightly oversized version of the desired object in standard resolution and then removing material with a higher-resolution subtractive process can achieve greater precision.
Some additive manufacturing techniques are capable of using multiple materials in the course of constructing parts. Some are able to print in multiple colors and color combinations simultaneously. Some also utilize supports when building. Supports are removable or dissolvable upon completion of the print, and are used to support overhanging features during construction.
| Type | Technologies | Materials |
|---|---|---|
| Extrusion | Fused deposition modeling (FDM) | Thermoplastics (e.g. PLA, ABS), HDPE, eutectic metals, edible materials, Rubber (Sugru), Modelling clay, Plasticine, RTV silicone, Porcelain, Metal clay (including Precious Metal Clay) |
| Wire | Electron Beam Freeform Fabrication(EBF3) | Almost any metal alloy |
| Granular | Direct metal laser sintering (DMLS) | Almost any metal alloy |
| Electron-beam melting(EBM) | Titanium alloys | |
| Selective laser melting(SLM) | Titanium alloys, Cobalt Chrome alloys, Stainless Steel, Aluminium | |
| Selective heat sintering(SHS) [25] | Thermoplastic powder | |
| Selective laser sintering(SLS) | Thermoplastics, metal powders, ceramic powders | |
| Powder bed and inkjet head 3D printing | Plaster-based 3D printing (PP) | Plaster |
| Laminated | Laminated object manufacturing (LOM) | Paper, metal foil, plastic film |
| Light polymerised | Stereolithography (SLA) | photopolymer |
| Digital Light Processing(DLP) | photopolymer |
Mask-image-projection-based stereolithography
In this technique a 3D digital model is sliced by a set of horizontal planes. Each slice is converted into a two-dimensional mask image. The mask image is then projected onto a photocurable liquid resin surface and light is projected onto the resin to cure it in the shape of the layer.
In research systems, the light is projected from below, allowing the resin to be quickly spread into uniform thin layers, reducing production time from hours to minutes.
The technique has been used to create objects composed of multiple materials that cure at different rates.
Commercially available devices such as Objet Connex apply the resin via small nozzles
Consumer use
Several projects and companies are making efforts to develop affordable 3D printers for home desktop use. Much of this work has been driven by and targeted at DIY/enthusiast/early adopter communities, with additional ties to the academic and hacker communities.
RepRap is one of the longest running projects in the desktop category. The RepRap project aims to produce a free and open source software (FOSS) 3D printer, whose full specifications are released under the GNU General Public License, and which is capable of replicating itself by printing many of its own (plastic) parts to create more machines. Research is under way to enable the device to print circuit boards and metal parts.
Because of the FOSS aims of RepRap, many related projects have used their design for inspiration, creating an ecosystem of related or derivative 3D printers, most of which are also open source designs. The availability of these open source designs means that variants of 3D printers are easy to invent. The quality and complexity of printer designs, however, as well as the quality of kit or finished products, varies greatly from project to project. This rapid development of open source 3D printers is gaining interest in many spheres as it enables hyper-customization and the use of public domaindesigns to fabricate open source appropriate technology through conduits such as Thingiverse and Cubify. This technology can also assist initiatives insustainable development since technologies are easily and economically made from resources available to local communities.
The cost of 3D printers has decreased dramatically since about 2010, with machines that used to cost $20,000 costing less than $1,000. For instance, as of 2013, several companies and individuals are selling parts to build various RepRap designs, with prices starting at about €400 /US$500.The open source Fab@Home project has developed printers for general use with anything that can be squirted through a nozzle, from chocolate to silicone sealant and chemical reactants. Printers following the project's designs have been available from suppliers in kits or in pre-assembled form since 2012 at prices in the US$2000 range. The Kickstarter funded Peachy Printer is designed to cost $100and several other new 3D printers are aimed at the small, inexpensive market including the mUVe3D and Lumifold. Professional grade 3D-printer crowdsourced costing $1499 is designed by Rapide 3D and has no fumes nor constant rattle during use.
As the costs of 3D printers have come down they are becoming more appealing financially to use for self-manufacturing of personal products.[8] In addition, 3D printing products at home may reduce the environmental impacts of manufacturing by reducing material use and distribution impacts.
The development and hyper-customization of the RepRap-based 3D printers has produced a new category of printers suitable for small business and consumer use. Manufacturers such as Solidoodle, RoBo, and RepRapPro have introduced models and kits priced at less than $1,000, thousands less than they were in September 2012. Depending on the application, the print resolution and speed of manufacturing lies somewhere between a personal printer and an industrial printer. A list of printers with pricing and other information is maintained. Most recently delta robots, like theTripodMaker, have been utilized for 3D printing to increase fabrication speed further.For delta 3D printers, due to its geometry and differentiation movements, the accuracy of the print depends on the position of the printer head.
Some companies are also offering software for 3D printing, as a support for hardware manufactured by other companies
Great Contribution In The Field Of Meical
Tissue engineering is the use of a combination of cells, engineering and materials methods, and suitable biochemical and physio-chemical factors to improve or replace biological functions. While it was once categorized as a sub-field of bio materials, having grown in scope and importance it can be considered as a field in its own right.
While most definitions of tissue engineering cover a broad range of applications, in practice the term is closely associated with applications that repair or replace portions of or whole tissues (i.e., bone, cartilage, blood vessels, bladder, skin, muscle etc.). Often, the tissues involved require certain mechanical and structural properties for proper functioning. The term has also been applied to efforts to perform specific biochemical functions usingcells within an artificially-created support system (e.g. an artificial pancreas, or a bio artificial liver). The term regenerative medicine is often used synonymously with tissue engineering, although those involved in regenerative medicine place more emphasis on the use of stem cells to produce tissues.
Organ-on-a-chip
An Organ-on-a-Chip (OC) is a multi-channel 3-D microfluidic cell culture chip that simulates the activities, mechanics and physiological response of entire organs and organ systems.[1] It constitutes the subject matter of significant biomedical engineering research, more precisely in bio-MEMS. The convergence of Lab-on-Chips (LOCs) and cell biology has permitted the study ofhuman physiology in an organ-specific context, introducing a novel model of in vitro multicellular human organisms. One day, they will perhaps abolish the need for animals in drug development and toxin testing.
Although multiple publications claim to have translated organ functions onto this interface, the movement towards this microfluidic application is still in its infancy. Organs-on-chips will vary in design and approach between different researchers. As such, validation and optimization of these systems will likely be a long process. Organs that have been simulated by microfluidic devices include the heart, the lung, kidney, artery, bone, cartilage, skin and more.
Nevertheless, building valid artificial organs requires not only a precise cellular manipulation, but a detailed understanding of the human body’s fundamental intricate response to any event. A common concern with Organs-on-Chips lies in the isolation of organs during testing. “If you don’t use as close to the total physiological system that you can, you’re likely to run into troubles”says William Haseltine, founder of Rockville, MD. Microfabrication, microelectronics and microfluidics offer the prospect of modeling sophisticated in vitro physiological responses under accurately simulated conditions.
Disadvantages of 3D Printers
In the prototyping sector of product development, 3D printing is lauded as being a fast, efficient means of creating parts to test for form, fit and function before said parts go into the manufacturing stage of development. While 3D printing is a viable technology in terms of validating parts and making sure that no design and engineering tweaks are necessary before any product is green-lighted for production, there are disadvantages in using the technology as well. These range from a limited use of materials to questions over whether the technology is feasible for short-run and long-run manufacturing.
Limited Materials
3D printed parts are built in additive fashion -- that is, layer-by-layer from the ground up. While the technology is a major process breakthrough, the materials that can be used are still limited. For instance, the 3D printing material of choice is plastic, as it can be deposited down in melted layers to form the final part. The kinds of plastic vary among the likes of high-strength and high temperature materials, so part strength can't accurately be tested in many cases. Some developers are offering metal as a material, but final parts often are not fully dense. There are several more specialized materials that companies are printing in, such as glass and gold, but such technologies have yet to be commercialized.
Manufacturing Limitations
3D printing is perfect for creating prototype parts because it's an economical, inexpensive way of creating one-run parts for which you don't have to create tooling. Parts typically are created in hours and changes to the design and engineering of the part can be made in a CAD (computer-aided design) file after the part is analyzed. But in terms of a manufacturing process, 3D printing is not a realistic option as of the date of publication. In manufacturing processes such as thermoforming and stamping, several parts are typically made in one minute, not hours.
Size
Parts created additively through 3D printing are also limited in size. For instance, the most affordable, common 3D printing machines typically are small enough to fit on your desktop, meaning they have build chamber sizes of similar proportions. There are 3D printers that are able to create larger parts, but they're much more expensive and thereby an unrealistic option for many companies. As a general rule of thumb, the larger the part that needs to be fabricated, the longer it takes to create.
