The Powder Bed Fusion (PBF) additive manufacturing process

  1. The Powder Bed Fusion (PBF) additive manufacturing process
  2. PBF technology, step by step
    1. Creation of the 3D model
    2. Part cutting – .STL format
    3. Print
    4. Scanning
    5. Cooling
  3. Post-processing
  4. PBF manufacturing possibilities at Mizar

That uses Powder Bed Fusion is an advanced additive manufacturing process that uses a high energy source(mainly lasers or electrons) to fuse powder particles layer by layer, resulting in a solid part. This technology allows us to generateparts in metal alloys or thermoplastic polymers, in a very

PBF manufacturing technologies share the basic principles of all additive manufacturing techniques and have common advantages such as extensive customization possibilities and simplification in terms of assembly. On the other hand, their specificities make them perfect for the production of complexgeometries.

Such characteristics have made this technology extremely popular for the production of high-value parts that are technically unfeasible through traditional manufacturing processes. The aerospace, automotiveand medicalsectors are recurrent users of this technology, which has shorter production times.

PROCESO FA PBF (1)

PBF technology step-by-step

The Powder Bed Fusion (PBF) manufacturing process consists of 5 steps to the final product:

  1. Creation of the 3D model

The additive manufacturing process begins with the creation of a 3D model through CAD(Computer-Assisted Design). Computer-aided design is the use of computer programs to create, modify and analyse three-dimensional (also two-dimensional) graphical representations of physical objects.

There are several methods of additive manufacturing designthat will be used depending on the objectives that are set (increase the mechanical properties of the part, reduce its weight, minimize the number of components, etc.). Likewise, in the design phase, it is convenient to integrate the simulation of the manufacturing process in order to draw conclusions about the behaviour of the part and minimise the appearance of possible defects.

This process begins with the creation of a 3D draft model and continues with the application of loadsor forces on the part. Thanks to these actions we know how to optimally distribute the material in a given volume subjected to different mechanical stresses . This is done with software that calculates the applied stresses.

  1. Part cutting – .STL format

Once this model is created, it is converted to .STL format (or .AMF / .3MF, newer formats), which is a triangulated representation of a 3D CAD model.

The three-dimensional model is divided into layers (slicing). Previously, it will be necessary to define the orientation of the machine or construction and to determine whether there will be supporting structures (which may be necessary for deposition of layers in near-horizontal orientations).

The information is sent to the printer, where the coating unit covers the platform with a powder coating. The optimum thickness of each layer of powder spread depends on the processing conditions and the material used, but generally ranges from  20 to 60 microns.

 

  1. Print

The printing process starts with the filling of the chamber of the printer with an inert gas (usually Argon or Nitrogen) to prevent oxidation of the material during fusing.

Subsequently, the printer is heated to the optimum printing temperature . The Powder Bed Fusion printers consist of two chambers, one powder chamber and one build chamber with a roller or knife to spread the powder on the platform.

  1. Scanning

The fiber optic laser (200/400 W) scans the cross section of the part, fusing the metallic particles together. When the layer is finished, the platform is moved down, allowing another layer of powder to be added. The operation is repeated until the final piece is obtained.

  1. Cooling

The 3D printer is allowed to cool  and the unmelted powderis removed from the tray to view the printed part. The workpiece is fixed to the build plate by means of the printing supports.

Post-processing

Post-processing of the Powder Bed Fusion (PBF) technology includes the following steps:

  • Removal of the powder
  • Thermal Stress Relief
  • Separationof the parts and material from support of the construction plate
  • Removalof the brackets of the parts
  • Shot blasting
  • Machining
  • Grinding

In addition, some parts may also require Hot Isostatic Pressing (HIP), additionalheat treatment, anodizing and inspection.

The post-processing is usually necessaryto enable them to adaptperfectly to the applicationsfor which they are intended and toimprovetheir mechanicalproperties, reduce the residual stress or improve the finishof the surface.

The post-processing method varies depending on the material and process selected.

PBF technology offers various manufacturing possibilities and at Mizar Additive we are specialists in the following PBF technologies:

  • EBM: Electron Beam Melting
  • DMLS: Direc Metal Laser Sintering
  • SLS: Selective Laser Sintering

In addition, we have extensive experience in both aerospaceand industrial sectors, and we put this experience at your disposal so that you can design and manufacture all types of components using additive manufacturing.

Do not hesitateto contact us for any questions you may have.

Gorka Fernández

Business Development at MIZAR Additive ➽ Metal and plastic additive manufacturing | Industrial Sector - Aerospace - Transport - Large Scientific Facilities ✱ Powder Bed Fusion - Fused Deposition Modeling – Polyjet
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