Selective laser melting (SLM)
Range from light metals to stainless and tool steels to superalloys.
Existing design principles can be rethought thanks to the SLM process (abbreviation for: selective laser melting). Functionality integrated into the workpiece, e.g., tool inserts that shorten production cycles by means of cooling channels close to the contour. Functional hinges with innovative kinematics. Or tool-free solutions for thin-walled, complex sheet metal constructions made of aluminium or steel.
Selective laser melting, or SLM for short, is based on the same additive and tool-free powder bedding process as selective laser sintering (SLS). However, metal powder is used as the base material. The object, which has previously been digitally produced using CAD data, is printed onto a building platform layer by layer.
With selective laser melting, very good mechanical characteristics are achieved, so that the components can be used without any problems as completely normal usable and loadable final components. All common post-processing options are also possible for components produced by SLM.
Laser melting, like laser sintering, the powder bedding process with various plastics, is part of additive manufacturing. Here, prototypes as well as fully functional and resilient small batches and series are realised in record time. In addition to the additive manufacturing of components, FKM also offers various finishing options. On request, the finished workpieces are polished, re-smoothed, galvanically nickel-plated and more. Metal cutting is also possible at the FKM factory. An in-house testing laboratory also ensures that the same quality requirements and standards are always met. In addition to checking the powder quality, FKM also carries out tensile tests or porosity measurements and more using scanners and CT. The latest technology with the highest quality standards is a matter of course at FKM.
Advantages of laser melting
- Diversity of materials – 7 metals
- Process reliability – Established 3D printing process
- Time saving
- Low production costs
- Production as required (conserving resources)
- Constructive freedom
- Function integration
What is laser melting?
SLM falls under the umbrella term of additive manufacturing. In contrast to conventional machining, i.e., metal cutting, processes, components are built up layer by layer on a moving construction platform. Laser melting is a powder-bed-based process with which complex geometries with internal cavities or integrated moving parts as well as extremely filigree objects can be realised. The process is ideal for producing new shapes and design ideas during project development and testing them directly on the model. In this way, workpieces can be haptically, optically and functionally tested for their fit under real conditions. If necessary, the corresponding structures can be optimised directly in the CAD programme and produced again in a time-efficient manner. A major advantage of the SLM process is the low production costs for filigree shapes and components with cavities – a big difference to previous manufacturing processes, where costs increase with complexity. Most of the powder that is not melted can be used for the next production run.
Selective laser melting: the process
The laser melting process is similar to the laser sintering process in which plastic powder is fused into objects instead of metal powder. In SLM, the selected metal powder is applied in a very thin layer to a movable building platform. A laser beam fuses the loose powder into solid structures with pinpoint accuracy according to a previously defined geometry using a CAD programme. The building platform is then moved downwards, and a new layer of metal powder is sprayed on. The steps of applying, powder –> melting –> lowering the platform, are repeated until the entire component has been created layer by layer. Thanks to the layer building process, extremely complex shapes with only a few support structures are possible. Metal powder that is not fused is collected afterwards and reused for further SLM projects. The cost calculation before printing is based on the CAD data set.
Selective Laser Melting (SLM)
|Construction space||Metal elements up to 250 x 250 x 310 mm or 400 x 800 x 500 mm (aluminium) in size are produced in a single operation during laser melting. For reasons of cost optimisation, solid components can be built to wall thickness (hollowed out) depending on the geometry.|
|Production time||After placing the order and any consultations with you, we usually produce your order within 1-5 days, depending on the size.|
|Costs||Together with you, we discuss the ideas and possibilities and calculate the costs on the basis of the CAD data sets we have compiled. We cannot make any general statements here, as each project that we implement is individual.|
|Tolerances||In most cases, you can assume a deviation of +/- 0.1 %, depending on the component geometry and the desired material. Further details can be found in our technical brochure.|
Laser melting materials
FKM has seven different metals permanently available as materials for laser melting. The choice of material depends on the use of the finished component. For example, does it have to withstand extreme mechanical stress, or should it be used in environments with very high temperatures? The answer determines the choice of metal powder.
The metals we use are:
- Aluminium AlSi10mg: AlSi10mg is suitable for building prototypes or small series with components that have to withstand high mechanical and dynamic loads.
- Stainless-steel 1.4404 and 1.4542 The two available stainless-steel variants are rustproof materials. The stainless-steel 1.4404 is also acid-resistant and excellently suited for the plant or automotive construction as well as in the field of medical technology. The 1.4542 variant is typically used for various industrial applications, as it is highly corrosion-resistant and also has good mechanical properties and excellent ductility.
- Tool steel 1.2709: This steel is highly loadable, even with a minimum wall thickness of only 0.25 mm. Tool inserts with near-contour cooling for injection moulding or aluminium pressure casting as well as functional components can be printed with this metal powder without any problems.
- Inconel 718: : Inconel 718 is a nickel-based alloy and is particularly suitable for components that are used in environments with very high temperatures, e.g., in the aerospace industry.
- Copper CuNi2SiCr: This material is a beryllium-free copper-based alloy that offers excellent thermal and electrical conductivity as well as corrosion resistance.
- Cobalt-chromium: This material is a CoCrW alloy and is used primarily in medical technology and dental prosthetics.
- Titanium Ti6Al4V: This light metal alloy is highly corrosion-resistant and biocompatible, making it suitable for many applications from aviation to medical technology.
The range of applications for laser-melted construction and small series parts is wide. Thanks to the freedom of geometry and the lightweight construction, SLM products can be found in aerospace technology, the automotive industry, mechanical engineering, medical technology and prosthetics, as well as in model-making or jewellery production. Due to the range of usable metal powders with different properties, there are hardly any limits to the use of workpieces created in the laser melting process. The products are fully functional and resilient. Thanks to the almost limitless design freedom, project-specific and completely individual construction and spare parts can be developed.
Background & history of SLM
The process of laser melting is still a fairly young technology. It was developed at the Fraunhofer Institute ILT (Institute for Laser Technology) in Aachen in the course of a research project in 1995, in cooperation with the Paderborn-based company F&S Stereolithographietechnik GmbH. SLM can also be found under other names. The background to this is that various machine manufacturers took over the patented process and modified it in different ways. The ILT itself calls the laser melting process Laser Powder Bed Fusion (L-PBF), while EOS calls it Direct Metal Laser Sintering (DMLS). LaserCUSING (Concept Laser), Laser Metal Fusion (Trumpf and Sisma3D) or Direct Metal Printing (3D Systems) are other names for the same process.