SLM Selective Laser Melting - Metals of Nothing
by Warren McLaren, Sydney 
on 03. 6.06
Michelangelo created the genius that is the statue David by removing what did not need to be there. The genius of Selective Laser Melting (SLM) is that it does the reverse. It builds shapes by mostly adding nothing. By nothing we mean air. It can achieve “nearly 90% reduction in weight but still retaining an extremely strong structure and stiffness.” Managing to include over 450 holes and channels per centimetre (0.39 inch). SLM (don’t ya just love three word acronyms (TWA)?) does this in stainless steel and chromium-cobalt, but can also work its magic in zinc, bronze and titanium and alloys thereof. Basically SLM builds structures by computerised fusing of metal powder, layer-by-layer. The reason this might be important is simply that we can use much less resources to get the results we need. For example, a car, truck, ship or aircraft that has metal components 90% lighter than standard, requires much less fuel to propel. SLM would appear (admittedly, to an untrained eye) to be the metal worlds equivalent of Aerogel. If each material lives up to its hype, a brave new world might indeed be possible. But as Lloyd rightly pointed out it’s more important to adjust attitude and actions, than rely on technology for the answers to the singular issues. ::Selective Laser Melting from MCP Group.
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I use rapid prototyping and similar techniques to this at work, and it is a great technique in that you can create objects that are unmanufacturable in any other process. A lot of the industry is looking forward to a time when 'direct manufacturing' means a lot of products are produced this way. In theory using only the quantity of metal (powder) you need means no waste etc.
However the negative green side that I have yet to find more about is the laser - 1 employee told me the lasers they use are only 2% efficient! Whether this could ever be a sustainable process, I have yet to find out.
What about E-Beam Melting? Apparently, it has much higher energy efficiency than Selective Laser Melting. The only downside is that it's slower, because it's scanning in 1-D only. But maybe they will find a solution for that, too.