WHAT IS SELECTIVE LASER MELTING?
Selective Laser Melting (SLM) is a method of applying additive processes to metal, and is also sometimes referred to as Powder Bed Fusion.
Much like other forms of 3D printing, a printable file and settings are selected for print. The printer begins by setting an even layer of the desired metal powder on the print bed, and a high-powered laser fully melts the metal in the exact areas dictated by the model. The next layer is set and the printer continues to melt and fuse each layer until the print is completed. The SLM print process produces objects that are very dense and strong. Parts can be manufactured using stainless steel, tool steel, titanium, cobalt, chrome and aluminum. Conventional manufacturing has limitations when it comes to the production of complex parts; the additive process overcomes them.
- Large range of materials
- Ability to tune properties
- Increased functionality
- Relatively low cost
- High resolution (near net shaped components)
- High quality control
- Relatively slow process
- Size restricted to build volume
- High power requirements
- Some post processing required
Some applications for this technology are multiplying and include:
- Aerospace – Air ducts, fixtures or mountings holding specific aeronautic instruments, laser-sintering fits both the needs of commercial and military aerospace
- Manufacturing – SLM can serve niche markets with low volumes at competitive costs. It is independent of economies of scale which liberates the user from achieving batch size optimization.
- Medical – Medical devices are highly precise, complex, high value products. This leads to a multitude of varieties and thus small volumes of the variants offered.
- Tooling – The direct process eliminates tool-path generation and multiple machining processes such as EDM. Tool inserts are built overnight or even in just a few hours. Also the freedom of design can be used to optimize tool performance, for example by integrating conformal cooling channels into the tool.
SELECTIVE LASER MELTING vs. DIRECT METAL LASER SINTERING
Though it is growing in popularity and use, SLM is not the only method of metal 3D printing.
Direct Metal Laser Sintering is another method. Instead of heating the metal to liquefaction, it is heated to slightly above the melting point. This allows the metal to bond on a molecular level, essentially ‘baking’ the metal print, much like a ceramic vase in a kiln. SLM and DMLS offer similar results, but there are some differences. SLM parts are typically more dense than DMLS components, whereas DMLS normally requires less power and since the sintering process does not melt, you can print from alloys containing materials with different melting points. You can even combine metal and plastic materials. A good example is Alumide, which is a mixture of nylon powder + aluminum powder.