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Wednesday, June 13, 2012

How does 3D printing work?

Science and techno world topic: Technology

Jewelry, toys, prototypes, models are just some of the applications of an industry growing exponentially. Within 10 years aims to revolutionize the manufacture.

Photo: 3d printed parts
When the mid-'80s began to circulate the first machines for 3D printing, few were willing to bet that the technology had a chance to drive a revolution in manufacturing. At the time the only available technique was the stereolithography, which consisted precisely in the print layers of photopolymer modeled through the use of ultraviolet light and gradually superimposed to form more or less faithful reproduction of a three-dimensional object. It was a slow and expensive process (a machine could cost as much as 500 thousand dollars) and therefore unattractive for large-scale application. 

Almost thirty years later the situation has drastically changed. The cost of equipment over the years has literally collapsed to the point that more than 10 years, many companies take advantage of 3D printing to build three-dimensional plastic prototypes without having to activate a process of production ad hoc. But it is only in recent years that the three-dimensional printing machines have reached such a low cost to enable a potential distribution at the household level. Suffice to say that there are companies like MakerBot who have already sold 3D printers small a price not exceeding one thousand euros (some even go below 500).

Of course, the basic concept of 3D printing is attractive: build a three dimensional model of your computer screen and orders the printer to use it to forge a true representation of plastic. But how will such a technology to revolutionize the manufacturing sector? Before answering this question, we need to go a little into detail. 

Techniques: the concept of additive manufacturing 

Most of the machines for 3D printing uses a production technique known as additive manufacturing: desired object is modeled by printing a layer at a time and superimposing those already printed. To do this you can proceed in several ways. 3D printers to laser sintering create the object by laser heating of the metal powders or thermoplastic and compacting at a specific location layer by layer. In the Fused Deposition Modeling is used a heated nozzle that melts the material of manufacture and places it three-dimensionally so as to reproduce the 3D model on the screen. There are other techniques used mainly in industry, such as Laminated Object Manufacturing, which consists when stacking thin layers of material which from time to time are engraved by laser.

There are also techniques that reflect the concept of stereolithography as the Digital Light Processing (photopolymer cured by means of light). 

Advantages: cheap, a few waste and increasing flexibility 

The benefits of 3D printing are endless, a little 'as possible fields of application. It should be stated at the outset that this technology is becoming more and more cheaply, machinery and ink (in fact most of the times is a plastic material) become more affordable, in addition the fabrication technique allows deposition of wasting very little raw material (where Instead the major processes producing tons and tons of waste). The type of materials used is expanding (albeit slowly) and multinationals operating in the automotive or aircraft has already begun to produce the first titanium parts. These same industries can thus produce individual components without having to launch a full and expensive production process, or just reprint some components running without having to reconsider the project as a whole.  Recently, techniques have been developed to produce objects made of several pieces already assembled. Furthermore, the laser sintering allows to forge objects with lighter materials than those usually used, and to obtain forms and structures previously inconceivable. 

Disadvantages: long processing times and quality control difficult 

It is one thing when a person wants to produce a handful of plastic pots to test their creative ambitions; another is when this technology is employed in the industry with the goal of producing complete pieces in bulk. The aspiring potter can spend time perfecting his model on the computer and then let the printer do the rest, but the industry needs the final result meets the high standards of quality (and safety) and, especially, has require that the results come quickly. 

The time here is the main problem of the 3D printing means the production of a single object costs a huge amount of time, and the object is more complicated (and larger) than this time expands. The second obstacle to the diffusion of these techniques is the difficulty in performing an effective quality control on the production of objects: science each piece product may be made up of thousands of layers of material, it is difficult to control which layers bring back imperfections and how this could impair the functionality of the object.

From this point of view the 3D printing technology should make many more steps forward, so as to ensure the production of objects and components identical in every detail. 

Prospects: the engine of the Boeing medical implants 

Some people want to buy it to make himself a plastic jewels, there are nerds who have already begun to shape virtual models for their action figures, but who has more interest in the future development of additive manufacturing technologies, manufacturing industries are. Despite the disadvantages and problems that we mentioned above, the 3D printing techniques (including laser sintering) are already used in various fields. General Electric, for example, has already begun to produce fuel injectors for engines of the Boeing 787 Dreamliner jet "printing" 20,000 different components then assembled into the engine. For the year ahead, the company already has plans to exploit the laser sintering to produce titanium strips to be mounted on the propeller blades that will serve to more easily remove the debris collected in flight. The European company EADS instead is using this technology to produce satellite components. But they are different areas that have decided to rely (or at least try) to 3D printing, such as the 'biomedical engineering, which is evaluating the possibility of using ceramic materials for the production of prostheses and implants. 

As we explained, because the 3D printing can really have a role in the manufacturing industry of the future, you must first overcome the limitations represented by the timing of production, materials used and quality control systems. But in the meantime the weather and are wasted on the subject has been debated to the point of generating two camps: there are some who focuses on copyright issues that a massive expansion of 3D printers could generate, and the other Who sees the additive in the manufacture a satisfactory substitute for teleportation . What is certain is that the techniques of 3D printing for now continue to depopulate as devices for prototyping low cost, an area in which you are reaching previously unattainable levels. 

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