Imagine that you’ve decided to organize your closet, but instead of measuring containers at a store to make sure they will work, you just go to your office, enter the measurements you want your containers to be, and print them out right there. Now imagine that you have to build a diorama of a famous Civil War battle for a project at school, and you use that same printer to construct all the soldiers, cannons and trees in perfect detail.
This technology may be closer than you think thanks to 3-D printing. 3-D printing is making it easier and faster to produce complex objects with multiple moving parts and intricate design, and soon it will be affordable enough to have at home.
Source : How Stuff Works
Additive manufacturing (AM) is the family of manufacturing technology that includes 3-D printing. AM is the means of creating an object by adding material to the object layer by layer. AM is the current terminology established by ASTM International (formerly the American Society for Testing and Materials). Throughout its history, additive manufacturing in general has gone by various names: stereo-lithography, 3-D layering and 3-D printing. This article uses 3-D printing because it seems to be the most common term used to describe AM products.
You can see some of the basic principles behind AM in caves; over thousands of years, dripping water creates layers and layers of mineral deposits, which accumulate to form stalagmites and stalactites. Unlike these natural formations, though, 3-D printing is much faster and follows a predetermined plan provided by computer software. The computer directs the 3-D printer to add each new layer as a precise cross-section of the final object.
Additive manufacturing and 3-D printing specifically, continues to grow. Technology that started out as a way to build fast prototypes is now a means of creating products for the medical, dental, aerospace and automotive industries. 3-D printing is also crossing over into toy and furniture manufacturing, art and fashion.
This article looks at the broad scope of 3-D printing, from its history and technologies to its wide range of uses, including printing your own 3-D models at home. First, let’s take a look at how 3-D printing got its start and how it is developing today.
History of 3-D Printing
The earliest use of additive manufacturing was in rapid prototyping (RP) during the late 1980s and early 1990s. Prototypes allow manufacturers a chance to examine an object’s design more closely and even test it before producing a finished product. RP allowed manufacturers to produce those prototypes much faster than before, often within days or sometimes hours of conceiving the design. In RP, designers create models using computer-aided design (CAD) software, and then machines follow that software model to determine how to construct the object. The process of building that object by “printing” its cross-sections layer by layer became known as 3-D printing.
The earliest development of 3-D printing technologies happened at Massachusetts Institute of Technology (MIT) and at a company called 3D Systems. In the early 1990s, MIT developed a procedure it trademarked with the name 3-D Printing, which it officially abbreviated as 3DP. As of February 2011, MIT has granted licenses to six companies to use and promote the 3DP process in its products
[source 1=”MIT” language=”:”][/source]
3D Systems, based in Rock Hill, SC, has pioneered and used a variety of 3-D printing approaches since its founding in 1986. It has even trademarked some of its technologies, such as the stereolithography apparatus (SLA) and selective laser sintering (SLS), each described later in this article. While MIT and 3D Systems remain leaders in the field of 3-D printing, other companies such as Z Corporation, Objet Geometries and Stratasys have also brought innovative new products to market, building on these AM technologies.
Direct and Binder 3-D Printing
One approach to 3-D printing is direct 3-D printing. Direct 3-D printing uses inkjet technology, which has been available for 2-D printing since the 1960s
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. Like in a 2-D inkjet printer, nozzles in a 3-D printer move back and forth dispensing a fluid. Unlike 2-D printing, though, the nozzles or the printing surface move up and down so multiple layers of material can over the same surface. Moreover, these printers don’t use ink; they dispense thick waxes and plastic polymers, which solidify to form each new cross-section of the sturdy 3-D object.
Photopolymerization and Sintering
Photopolymerization is a 3-D printing technology whereby drops of a liquid plastic are exposed to a laser beam of ultraviolet light. During this exposure, the light converts the liquid into a solid. The term comes from the roots photo, meaning light, and polymer, which describes the chemical composition of the solid plastic.
In the 2000s, the Piedmont Triad Center for Advanced Manufacturing (PTCAM) was a partnership of schools and businesses that provided hands-on training in metalworking skills in North Carolina. Some of PT CAM’s training incorporated a stereolithography apparatus (SLA) by 3D Systems. SLA uses photopolymerization, directing a laser across a vat of liquid plastic calledphotopolymer. As with inkjet 3-D printing, the SLA repeats this process layer by layer until the print is finished.
The 3-D Printing Process
No matter which approach a 3-D printer uses, the overall printing process is generally the same. In their book “Additive Manufacturing Technologies: Rapid Prototyping to Direct Digital Manufacturing,” Ian Gibson, David W. Rosen and Brent Stucker list the following eight steps in the generic AM process:
- Step 1: CAD — Produce a 3-D model using computer-aided design (CAD) software. The software may provide some hint as to the structural integrity you can expect in the finished product, too, using scientific data about certain materials to create virtual simulations of how the object will behave under certain conditions.
- Step 2: Conversion to STL — Convert the CAD drawing to the STL format. STL, which is an acronym forstandard tessellation language, is a file format developed for 3D Systems in 1987 for use by itsstereolithography apparatus (SLA) machines[source 1=”RapidToday.com” language=”:”][/source]
. Most 3-D printers can use STL files in addition to some proprietary file types such as ZPR by Z Corporation and ObjDF by Objet Geometries.
- Step 3: Transfer to AM Machine and STL File Manipulation — A user copies the STL file to the computer that controls the 3-D printer. There, the user can designate the size and orientation for printing. This is similar to the way you would set up a 2-D printout to print 2-sided or in landscape versus. portrait orientation.
- Step 4: Machine Setup — Each machine has its own requirements for how to prepare for a new print job. This includes refilling the polymers, binders and other consumables the printer will use. It also covers adding a tray to serve as a foundation or adding the material to build temporary water-soluble supports.
- Step 5: Build — Let the machine do its thing; the build process is mostly automatic. Each layer is usually about 0.1 mm thick, though it can be much thinner or thicker[source 1=”Wohlers” language=”:”][/source]
. Depending on the object’s size, the machine and the materials used, this process could take hours or even days to complete. Be sure to check on the machine periodically to make sure there are no errors.
- Step 6: Removal — Remove the printed object (or multiple objects in some cases) from the machine. Be sure to take any safety precautions to avoid injury such as wearing gloves to protect yourself from hot surfaces or toxic chemicals.
- Step 7: Postprocessing — Many 3-D printers will require some amount of post-processing for the printed object. This could include brushing off any remaining powder or bathing the printed object to remove water-soluble supports. The new print may be weak during this step since some materials require time to cure, so caution might be necessary to ensure that it doesn’t break or fall apart.
- Step 8: Application — Make use of the newly printed object or objects.