MANUFACTURING OF COMPONENTS USING SELECTIVE LASER MELTING (SLM)

This additive manufacturing process was developed and patented in 1997. With its patent expired in 2017, it has since improved in quality, and precision, and has found new areas of application. The medtech and aerospace industries were the first to adopt this technology. Its rapid evolution has now opened doors to the worlds of jewellery and watchmaking.

This method is exclusively concerned with metallic alloys, however diverse they may be. Titanium, stainless steel, and platinum are currently eligible for this technology.

The principle of selective laser melting involves depositing the chosen alloy in powder form, with grains reduced to the finest particle (between 20 and 200μm depending on the alloy), on the surface of a bed plate. Adhering perfectly to the volumetric plan of the component, the laser melts the powder with specific intensity and duration, achieving precision to the size of a particle (i.e., between 20 and 200μm). The bed plate is then lowered by the thickness of the first layer created. A new layer of alloy powder is added and fused. This process is repeated layer by layer in absolute accordance with the volumetric plan of the component to be produced.

The excessive powder (not melted) can easily be reused later without reprocessing.

The advantages of this technology are numerous. It allows for the creation of components with structures and designs previously unachievable (rigidity, lightness). This method generates no material waste, thus incurring no recycling costs—particularly beneficial when dealing with precious metals. Moreover, the density of the material is exceptionally high. No mechanical stress is exerted on the component during its fabrication, which does not require any subsequent heat treatments. Nevertheless, depending on the laser intensity, exposure duration, and cooling time, heat treatments can be applied during the manufacturing process.

With this technology,  style and design know no limits, and the technical boundaries are pushed daily. However, this technology to date finds applications only in the casing of watches (cases, bracelets, dials). A watch case produced with SLM will require further machining to achieve the required precision and obtain the desired surface finishes.

The level of precision of selective laser melting is currently insufficient to manufacture movement components. But this technology proves very promising for watch casing and prototyping.

Currently, the bulk of research focuses on developing alloys specifically tailored for this technology. By parameterizing them with the intensity and duration of the fusion, it is possible to exploit new mechanical or physical properties of the material.