Surface finishing of parts produced by additive manufacturing

The production of metal parts using powder-bed additive manufacturing represents a revolution in the industrial world. This technology offers numerous advantages and overcomes many of the limitations imposed by conventional production techniques. For example, complex prototypes can now be produced rapidly, and part manufacturing costs are partially independent of geometric complexity. Machine suppliers are currently working to increase the volumes available for part production and the associated productivity, which will lead to industrialization of the process.

Nevertheless, this technology has one potentially fatal flaw: the high roughness of the parts leaving the machine. This high level of roughness is a direct consequence of the particle size of the powders used, the thermal behavior of the process, and the supports required to build the parts. Appropriate strategies for managing laser power and positioning the supports help to mitigate these defects. Even so, when they leave the machine, parts often have surface properties that are incompatible with their final use. Machining the whole part could be a solution to this problem, but it contradicts the very essence of the manufacturing method, particularly in terms of accessibility.

The major impacts of these surface defects concern both mechanical properties, such as fatigue, and the surface post-treatments required for their final application. These defects therefore become a hindrance to the development of additive technologies, and a potential blocking factor for certain applications. Improving the roughness of metal parts produced by additive manufacturing is therefore a challenge for which suitable surface treatment techniques need to be developed and applied.

This article looks at all the subtractive methods that can be used to improve the surface properties obtained after additive manufacturing. Mechanical and electrochemical treatments are discussed, as well as commercial processes already available on the market.