Powder Bed Fusion: Pros and Cons | Additive Manufacturing & 3D Printing

Powder Bed Fusion is a 3D printing process that involves partially melting powder particles in a pattern and letting them solidify into a pattern. Using layers, the fused powder patterns stack to create a part.

More Materials

The powder that melts may be the main material, or a binder material that acts as an adhesive. Since a binder material can be used to fuse particles, multiple materials can be used. Ceramics, metals, and polymers are some of the materials that can be used with PBF. Metal powders can be fully melted when the heat source (laser) is powerful and moves slowly, giving denser parts with better properties.

With full melting on metals, the part usually achieves a density over 99% (that is, very little porosity). This means that parts printed with PBF can approach the same material properties as bulk material. For some Titanium alloys, the material strength is actually better with full melting in a PBF process! Compare this to most 3D printed materials, which tend to be porous and weaker than conventional materials.

Powder Recycling

The powder is expensive, but even more expensive is throwing out partially melted or unused powder. To speed up the print process, powder is often preheated. This means that some powder is affected by the heat despite not being in the final part. For any PBF process of scale, the cost of recycling or throwing out powder needs to be considered.

Supports

On one hand, you might not really needs supports for some materials. This is because the powder (which has been scraped over for the next pattern) serves as a support. However, support should be considered for metal or asymmetrical parts. Residual stresses from printing can cause the part to warp. Cutting out metal supports and other post processing measures are a drawback of PBF.

Surface and Quality

With PBF, powder is being fused together, so most parts will have a noticeably lesser quality surface finish than a part made from other processes. Vat Polymerization, for instance, should have better surface quality than powder bed fusion. If you are willing to pay more for a better printer and powder, you can get smaller particles, which will have a better surface finish. However, small particles tend to clump and are more difficult to spread into a uniform layer.

Most PBF parts should shrink about 3 to 4% of the true size, which can lead to even more warping if the part is metal or asymmetrical.

Longer Print Times

Because the powder bed is preheated, and the part needs to cool, the print time is usually longer than other processes.