Additive Manufacturing of Microchannels

The field of additive manufacturing (AM) has seen interest particularly in the gas turbine industry due to the cheaper and faster manufacturing. AM methods using metal include selective laser sintering (SLS), selective laser melting (SLM), electron beam melting (EBM) and direct metal laser sintering (DMLS). These technologies enable building metal parts with complex geometries such as small or winding internal passages that cannot be realized with any other method of manufacturing currently available. Additionally, the cost of making a part with AM does not generally increase with increased complexity. Metals of varying compositions, including high nickel or titanium alloys, can be used for fabrication without a significant increase in difficulty compared ti standard ferrous or nonferrous metals.

A major challenge that exists when using AM for producing metal parts is the large surface roughness that is an inherent result of the process. Pressure losses and heat transfer in small channels are affected considerably by the roughness of the channel walls. Most, if not all, roughness removal technologies have limitations that prelude them from being used on small, tortuous passages. Our studies have pointed to these roughness levels being a direct effect of the build orientation of the channel. Resulting from this roughness is enhanced pressure loss with a minimal increase in heat transfer.