The rapid manufacturing and Selective Laser Melting

Stereolitografia, Close-Up Engineering
fraser-ais.com

In this article we will see a technology belonging to the world of 3D printing that can be used for the production of “usable items” and not just prototypes, the Selective Laser Melting.

One of the main problems of rapid manufacturing lies in the type of materials processed, that is, in the fact that it is mainly variety of plastics. This technique, however, has the characteristic to treat a wide variety of metals among which we can cite steel, titanium, inconel (a metal able to withstand high temperatures) and aluminum. In this way it is possible to produce not only the prototype (typical goal of a technology 3D printing industry) but you can start a real production of the final object. Obviously means small objects produced in small series, given the size of the working volume of the machines (less than one square meter).

The desired object is obtained by projecting a laser beam selectively on a metal powder which in this way is melted. The process involves a series of problems that are typical of welding techniques already known to the industry and solvable, and then, in the same way. The working chamber, in fact, is heated to have a cooling sweeter – the objective is to avoid distortions in the material- and it is also present inert gas to avoid the phenomenon of oxidation. The selective laser melting provides some key steps:

1) Development of the CAD file that is passed to the machine SLA;

2) Preparation of the machine for processing;

3) Manufacture of the object layer by layer. For each section of the machine will build the object, it is not necessary to make the elements that will support since that task falls to the metal powder present in the working chamber. The transition from the current layer to the next layer takes place thanks to a mobile platform in the vertical direction.

4) Extraction of the object from the working chamber.

An application made with this technique is the frame mountain bike titanium (viewable in the image of the article) designed by Empire cycles Ltd – titanium instead of carbon fiber because it allows for lightweight strength is at the same time – and made a Renishaw machine.

In this way there was also the possibility of using software that would optimize topologically the structure of the frame (ie placing material where there needs without running the risk of affected in resistance).

Edited by Salvatore Orlando, BEng Management Engineering.

Header image credits: renishaw.jp
 
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