SLM
The abbreviation SLM stands for selective laser melting. The SLM process or SLM printing is part of additive manufacturing. In this process, metal workpieces are produced using an SLM 3D printer.
How an SLM 3D printer works
Selective Laser Melting (SLM) is based on the layer build-up principle, in which metal powder is selectively melted by a powerful laser to create complex geometries. It is a generative, build-up process, in contrast to the subtractive process of machining, for example. Other terms for 3D printing are rapid prototyping or rapid manufacturing.
The SLM printing process begins with a thin layer of metal powder that is applied to a building platform (powder bed). A high-energy laser beam melts specific areas of the powder that correspond to the design of the component. As soon as the first layer has solidified, a new layer of powder is applied and the process is repeated until the complete component has been created.
With SLM, it is possible to produce completely dense and mechanically resilient metal parts. The process is particularly suitable for demanding applications in the aerospace, medical technology and automotive industries: with selective laser melting (SLM), you can produce complex geometries, internal structures and functional components that would be difficult or impossible to realise using conventional manufacturing methods.
SLM uses a variety of metal alloys, including titanium, aluminium, stainless steel and nickel alloys. This opens up a wide range of possible applications. To prevent oxidation of the metal powder during the process, printing takes place in an inert protective atmosphere, see below.
The high precision of the lasering and the fine control over the melting process make it possible to produce components with minimal material waste and optimum material utilisation. This makes Selective Laser Melting (SLM) a cost-efficient and sustainable solution in additive manufacturing metal 3D printing.
Other types of metal 3D printers
On maschinenauswahl.de you will find an overview of all methods for metal 3D printing in additive manufacturing. Other methods include:
- Powder bed and electron beam melting (EBM)
- Powder nozzle and laser engineered net shaping (LENS)
- Wire arc additive manufacturing (WAAM)
- Melting nozzle and fused deposition modelling (FDM)
- Powder bonding and binder jetting (BJ)
- Inkjet technology and nanoparticle jetting (NPJ)
- Hybrid machines (application/removal)
Components of an SLM 3D printer
A metal 3D printer for selective laser melting (SLM) consists of the following components: A build platform on which the component is built up layer by layer. A high-performance laser precisely melts the metal powder. A powder application system distributes the metal powder evenly. A protective chamber with inert gas prevents oxidation during the printing process. A cooling system regulates the temperature of the lasering and the component. The control unit monitors the entire printing process and ensures the precision of the build-up. Filter systems ensure clean working conditions by removing excess powder.
SLM in industrial production
Examples of workpieces that are produced using selective laser melting:
- Aerospace: turbine blades, engine components, structural components, heat shields and combustion chambers
- Medical technology: dental implants, hip prostheses, spinal implants, bone plates and surgical instruments
- Automotive industry: engine blocks, turbochargers, gearbox housings, exhaust manifolds and brake calipers
Materials and success factors in selective laser melting (SLM)
In powder bed technology with SLM, the same conditions apply to the various metals and alloys as in the process with a powder nozzle and laser engineered net shaping. The materials are susceptible to oxidation, so processing requires a stable and inert protective atmosphere. This atmosphere is created in a protective chamber in the form of gases. Gases are usually used:
- For stainless steel: argon or nitrogen
- For titanium: argon
- For nickel: argon or helium
- For aluminium: argon
The purity of the metal powder used is a decisive quality factor in metal 3D printing. High-purity, fine-grained alloy powder is recommended. The powder quality must be constantly monitored during the 3D printing process. This allows you to achieve the desired mechanical properties for the workpiece.
Each of the metal alloys mentioned above reacts differently to the thermal processes that take place during SLM. There is a risk of cracking and the workpiece may also warp slightly.
- Stainless steel has a high thermal conductivity, which is why precise temperature control is required.
- Titanium has low thermal conductivity, which makes it necessary to control the temperature and cooling rates during printing.
- Nickel alloys have good thermal conductivity and are prone to high thermal expansion, so heat dissipation should be monitored.
- Aluminium also has a high thermal conductivity.
In selective laser melting (SLM), temperature control requires corresponding attention, with laser strength and layer height being important factors. They also determine the density and strength of the component.
Aluminium tends to be porous. The metal powder must be kept particularly even and pure. If dense and stable components are to be produced, precise powder dosing and the correct laser strength are of great importance. Maintenance tools for cleaning print nozzles and laser optics are mandatory.
Leading manufacturers of SLM 3D printers
In our manufacturers directory, you will find companies that produce metal 3D printers for selective laser melting.
The following terms are often searched for: Colibrium Additive SLM, EOS GmbH SLM, 3D Systems SLM, DMG Mori SLM, Nikon SLM Solutions, REALizer SLM
Search now on maschinenauswahl.de for the metal 3D printer for SLM that matches your production requirements.