3D Printing

3D printing of architectural designs Image: http://social.rollins.edu

Bishwajeet Shrestha
B.E 4th Year Mechanical Engineering

What is a 3D printer?

3D printers are such machines that can make everyday things from 3D models designed in the computer. They are remarkable because they can produce different kinds of objects, in different materials. A 3D printer can make pretty much anything from ceramic cups to plastic toys, metal machine parts, stoneware vases, fancy chocolate cakes or even some human body parts these days including nose, skin, ear, lungs, and tissues. They replace traditional factory production lines with a single machine.

What is 3D printing and how does it work?

3D printing or desktop fabrication or additive manufacturing is a process of making three-dimensional solid objects from a digital file. It is a prototyping process whereby a real object is created from a 3D design. The digital 3D-model is saved in STL format and then sent to a 3D printer. The 3D printer then prints the design layer by layer and forms a real object. The creation of a 3D printed object is achieved using additive processes. In an additive process, an object is created by laying down successive layers of material until the object is created. Each of these layers can be seen as a thinly sliced horizontal cross-section of the eventual object.
It all starts with making a virtual design of the object you want to create. This virtual design is, for instance, a CAD (Computer Aided Design) file. This CAD file is created using a 3D modeling application or with a 3D scanner (process being called as reverse engineering). A 3D scanner can make a 3D digital copy of an object.

3D printer Image: www.up3d.com

From 3D model to 3D printer

The 3D models can be prepared from AutoCAD, Solid Works, CATIA, Fusion 360, Sketch Up and much other software. The 3D model files need to be exported to STL format for 3D printing the object. A 3D model is prepared before it is ready to be 3D printed. It is called slicing. Slicing is dividing a 3D model into hundreds or thousands of horizontal layers and needs to be done with software. Sometimes a 3D model can be sliced from within a 3D modeling software application. It is also possible that you are forced to use a certain slicing tool for a certain 3D printer. We can send the 3D model into the 3D printer via USB, SD or Wi-Fi.

Different Types of 3D Printers

3D printers differ in mechanical arrangements and coordinate systems. The most popular mechanical arrangements for 3D printers are Cartesian-XY-head, Cartesian-XZ-head, Delta, CoreXY, Polar, Scara (robot arm) etc. Cartesian-XY-head is the extruder head moves over the X and Y-axis and the bed over the Z. Z-axis movement on such a 3D printer is very precise and requires very low accelerations. Delta is the extruder head is suspended by three arms in a triangular configuration. They have a circular print bed. Polar 3D printers have a rotating print bed, plus an extruder head that can move left, right, up and down.

Different types of 3D Printing technologies and Processes

Not all 3D printers use the same technology. There are several ways to print and all those available are additive, differing mainly in the way layers are built to create the final object.
Some methods use melting or softening material to produce the layers. Selective Laser Sintering (SLS) and Fused Deposition Modeling (FDM) are the most common technologies using this way of 3D printing. Another method is when we talk about curing a photo-reactive resin with a UV laser or another similar power source one layer at a time. The most common technology using this method is called Stereolithography (SLA).

Examples & applications of 3D printing

Applications include rapid prototyping, architectural scale models, healthcare (3D printed prosthetics and 3D printing with human tissue) and entertainment (e.g. movie props).
Other examples of 3D printing would include reconstructing fossils in paleontology, replicating ancient artifacts in archaeology, reconstructing bones and body parts in forensic pathology and reconstructing heavily damaged evidence acquired from crime scene investigations.
Many different materials can be used for 3D printing, such as ABS plastic, PLA, polyamide (nylon), glass filled polyamide, stereolithography materials (epoxy resins), silver, titanium, steel, wax, photopolymers, and polycarbonate.
The worldwide 3D printing industry is expected to grow from $3.07B in revenue in 2013 to $12.8B by 2018, and exceed $21B in worldwide revenue by 2020. As it evolves, 3D printing technology is destined to transform almost every major industry and change the way we live, work, and play in the future.
Source: Wohlers Report 2015

What are the limitations?

Although buying a 3D printer is much cheaper than setting up a factory, the cost per item you produce is higher, so the economics of 3D printing don’t stack-up against traditional mass production yet. It also can’t match the smooth finish of industrial machines, nor offer the variety of materials or range of sizes available through industrial processes. But, like so many household technologies, the prices will come down and 3D printer capabilities will improve over time.
Some website with 3D models database are 3D Marvels, 3D Via, GrabCAD, Google 3D Warehouse etc. Companies like Shapeways, Materialise, Sculpteo and Ponoko provide online 3D printing service.

References:
1. https://3dprinting.com/what-is-3d-printing/
2. https://www.3dhubs.com/what-is-3d-printing
3. http://mashable.com/category/3d-printing/
4. https://3dprintingindustry.com

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