Metal 3D Printing

Additive manufacturing as applied to 3D printing refers to the automated process of translating digital 3D modeling data into a physical 3D part layer-by-layer from dispensed material. Current metal 3D printing machines use SLS, SLM, and DMLS style printing.

SLS – Selective Laser Sintering – Process of using an automated laser to sinter compacted layers of powdered material (typically nylon-based) to form a 3D part. Once the base layer is sintered, a new layer of compacted powdered material is dispensed and the laser then sinters the new powder to the previously sintered material. This process is fast and functional, not requiring additional supports due to the powder bed acting as a support.

DMLS – Direct Metal Laser Sintering – Similar to SLS printing, DMLS uses metal powder and a higher powered laser to sinter the material. Common metal powder include stainless steel, titanium, aluminum, and Inconel. Disadvantages of DMLS printing are likeliness of surface porosity that can be removed during post processing.

SLM – Selective Laser Melting – Process of using high powered lasers to fuse metal powders together by locally melting the material, a process similar to standard welding. SLM printing generally produces a stronger part with less risk of porosity, but requires more design parameters. More heat causes more thermal stresses which can hinder manufacturing and result in poor quality parts or print failure.

Each process is performed using a high powered and extremely accurate laser, 3D modeling data, and dispensed metal in the form of a very fine powder. As the metal powder is dispensed (either as a layer or selectively as the laser is operational) the laser either melts or sinters as dictated by the locations in the 3D model. Sintering metal powder will solidify the particles and fuse the material together without welding, whereas melting will introduce different bead size, surface finish, and porosity within the finished product. The primary use-case of 3D printing additive manufacturing besides rapid prototyping is the development of designs and products that are ultimately impossible to build using traditional subtractive manufacturing methods or castings.

Read about Certification and Testing for Additive Manufacturing

Read about Value Added from Additive Manufacturing or 3D Printing

Jarrett Linowes

Mechanical Engineer

omniamfg@gmail.com

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