Metal 3D printing in Binder Jetting technology generates much lower greenhouse gas emissions than the casting process

AMGTA (Additive Manufacturer Green Trade Association), a global trade organization established to promote the environmental benefits of additive manufacturing, has announced preliminary results of a life cycle analysis of products made of metals with Binder Jetting technology. The paper entitled “Comparative Life Cycle Assessment: Comparing Casting Technology with Binder Jetting for an Industrial Part” outlines the significant environmental benefits of using this 3D printing technology compared to traditional metal casting techniques.

The AMGTA-commissioned study was conducted by the Yale School of the Environment (YSE) in partnership with Desktop Metal, a manufacturer of industrial 3D binder jetting printers, and Trane Technologies, an American “climate innovator.” To determine the comparative environmental impact, the team analyzed the production process of a steel coil chiller in a Trane HVAC system using both manufacturing methods.

The Binder Jetting technology in metal 3D printing consists in combining metal powders with a special binder (binder) and subsequent baking of the parts. This process is significantly different from other metal 3D printing methods, such as selective laser melting (SLM / DMLS / DMP / PBF etc.). A layer of powdered metal is applied to the working platform, onto which a binder is sprayed, “gluing” the shape of a single layer. The process is then repeated until the desired part geometry is achieved.

After the 3D printing process is complete, the block with the powder and cured binder is dried to remove excess moisture. In order to obtain full density and appropriate mechanical properties, the printed object is subjected to a sintering process. During this process, the object is heated in a furnace to a temperature just below the melting point of the powder. The binder is burned off and the metal particles fuse together to form a solid, dense object. After sintering, the object is typically subjected to further processing, such as grinding or heat treatment, to achieve the final properties and surface finish.

The study, which took place at the Trane New Mexico facility, compared the traditional casting process followed by machining, electroplating and finishing with the Binder Jetting process. The same coating and finishing steps were used in both production processes. By comparing the two production methods, the team found that the greenhouse gas emissions from additive manufacturing were reduced by 38% compared to the traditional casting-based process.

At the same time, the study noted that redesigning the parts to achieve a lightweight lattice structure ultimately had a “negligible” impact on reducing greenhouse gas emissions. This is because most of the electricity was used for the 3D printing, curing and sintering steps, which would not be affected by lattice-type structures. The overall dimensions of the part and the efficient use of the volume of the 3D printer played a more important role than reducing the weight of the part.

The study also suggests that a 10% reduction in the mass of the spiral assembly would lead to a 1% reduction in greenhouse gas emissions. However, the lightness of the parts may have environmental benefits in the use phase, which was not assessed in this study. In addition, it was emphasized that the volume of production plays a significant role in greenhouse gas emissions in the 3D printing process. This is especially true for less efficient use of build volume and small batch operations.

The energy mix at the production site, and whether that power grid was sustainably produced, had a “significant impact on greenhouse gas emissions.” It was noted that production in an energy-sustainable location provides environmental benefits for both production processes. However, the difference in environmental impact between the two methods “shrinks” as the energy mix becomes greener.

The study also assessed the impact of materials production, showing that the environmental impact of metal powder production was about twice that of steel casting. However, this increase represented a small proportion of overall greenhouse gas emissions and thus played a “negligible” role in the overall findings.

Source: www.businesswire.com