Metal additive

Selective Laser Melting (SLM)

Powder bed fusion is the leading technology in the precision manufacturing of geometrycally complex metal components.

There are different processes depending on the heat source used (laser beam or electrons), and on the material melting degree (sintered or fusion).

The most widespread process to manufacture metal parts is the so-called selective laser melting or SLM. It is also known as DMLS (Direct Metal Laser Sintering) or Laser Cusing.

The process starts by creating a three-dimensional model (3D) using computer-assisted design (CAD) software. This 3D model is saved as a STL format file, which is the triangulated representation of the model. Then, the software divides the file data into individual layers and they are sent to the SLM equipment.

In the configuration of a SLM machine, a (laser) heat source selectively melts a layer of powder, previously deposited in very fine, even layers (the layers indicated in the 3D) on a platform, generating the contour and interior of the part. This building platform descends, in z-axis after each layer, by a distance equal to the layer thickness (normally between 20 and 50 microns), an action that is repeated until the part is completed.

After building the part, and depending on its application, finish enhancement activities and/or thermal treatments may be needed to improve the mechanical properties.

Currently, materials such as stainless steel, tool steel, titanium alloys, nickel-based alloys, and aluminium alloys, among others, can be processed by SLM.

Densities of over 99.9% are often achieved, with a surface finish of around 4-10 μm. Therefore, this technology is very useful to manufacture final parts with very complex shapes and structures, with thin walls and/or hidden cavities or channels.

What we are currently working on

  • Optimization of powder compositions in agreement with the characteristics of the SLM process.
  • Development of customized AD HOC alignments for SLM technology.
  • Optimization of process parameters to achieve a dense and effect-free material.
  • Pre-processing stages: design of manufacturing process, definition of optimal support strategy, optimal orientation, etc.
  • Numerical simulation models based on FEM (Finite Element Method): to predict distortions in process and offset to ensure quality and repetitiveness.
  • Determination and optimization of mechanical properties.
  • Post-processing stages: optimization of heat and surface treatments, elimination of supports, guarantee of dimensional tolerances, etc.
  • Quality assurance: development of monitoring system to detect defects, non-destructive inspection techniques (NDT).
  • Support to the process industrialization.

Specific Equipment

MCP SLM Realizer 250 (From Realizer)

  • Year: 2007.
  • Building platform size 250 x 250 x 220 mm.
  • 200 W fibre laser.

SLM 61 - SLM 280 HL (from SLM Solutions)

  • Year: 2014.
  • Building platform size: 280 x 280 x 350 mm.
  • 400 W fibre laser. Flow package upgrade 2018.

RenAM 500Q (from Renishaw)

  • Year: 2018.
  • Building platform size: 250 x 250 x 350 mm.
  • 2 fibre lasers 500 W
  • Double melt pool monitoring system.

Publications and downloads

A. Martin, M. Vilanova, E.Gil, M. San Sebastian, C. Y. Wang, S. Milenkovic, M. T. Pérez-Prado, C. M. Cepeda-Jiménez
Influence of the Zr content on the processability of a high strength Al-Zn-Mg-Cu-Zr alloy by laser powder bed fusion
M. Vilanova, F. Garciandia, S. Sainz, D. Jorge-Badiola, T. Guraya, M. San Sebastian
The limit of hot isostatic pressing for healing cracks present in an additively manufactured nickel superalloy
Journal of Materials Processing Technology. Volume 300, February 2022, 117398.
A. Martin, M. San Sebastian, E. Gil, C.Y. Wang, S. Milenkovic, M.T. Pérez-Prado, C.M. Cepeda-Jiménez
Effect of the heat treatment on the microstructure and hardness evolution of a AlSi10MgCu alloy designed for laser powder bed fusion
Materials Science and Engineering: A. Volume 819, 5 July 2021, 141487.
I. Setien, M. Chiumenti, S. van der Veen, F. Garciandia, M. San Sebastian, A. Echeverria.
Empirical Methodology to Determine Inherent Strains in Additive Manufacturing. Computers and Mathematics with Applications
A. Iturrioz, E. Gil, F. Garciandia, M.M. Petite, A.M. Mancisidor, M. San Sebastián.
Selective laser melting of AlSi10Mg alloy: influence of heat treatment condition on mechanical properties and microstructure. Welding in the World, 62, 885-892.
A.M. Mancisidor, E. Gil, F. Garciandia, M. San Sebastián, O. Lizaso, M. Escubi.
Stirling engine regenerator based on lattice structures manufactured by selective laser melting. Procedia CIRP, 74, 72-75
P. Alvarez, J. Ecenarro, I. Setien, M. San Sebastian, A. Echevarria, L. Eciolaza.
Computationally efficient distortion prediction in Powder Bed Fusion Additive Manufacturing
International Journal of Engineering Research & Science (IJOER), 2, 39-46.
A. M. Mancisidor, F. Garciandia, M. San Sebastián, P. Álvarez, J. Díaz, I. Unanue.
Reduction of the Residual Porosity in Parts Manufactured by Selective Laser Melting Using Skywriting and High Focus Offset Strategies. Physics Procedia, 83, 864-873.

Success Cases

Optimized active flow control actuators manufactured with SLM for UHBR engine-powered aircraft.


Development of new active flow control actuators (AFC) with innovative aeronautical designs to improve the fluid flow in future UHBR engines.


Manufacture by SLM of flow control actuators with optimized and complex designs that can be installed in small spaces in aircraft with high-efficiency engines.

Partners or strategic alliances

Development carried out within the framework of the FLOWCAASH project (Clean Sky2 Call) with AIRBUS as partners.

Manufacture of hydraulic blocks by means of additive manufacturing.


Design optimization so as to permit manufacture by SLM. Improvement of functionality by modifying trajectories and/or shapes of interior channels. Weight reduction.


71% weight reduction has been achieved by eliminating material that has no functionality. The functionality achieved with the additive blocks is comparable to that of the traditional block, but using less material. The technical feasibility of the additive hydraulic blocks has been proven.

Partners or strategic alliances

Development carried out within the framework of the ADHYBLOCK and SHOPEN projects, financed within the Hazitek call of the Basque government, with HINE as partners.


Challenges to be faced in the coming years:

Weight reduction.
Zero defect manufacturing.
Digital factory.
Flexible manufacturing.