By Mark Norfolk on Thursday, February 25th, 2016
Fabrisoinc has been 3D printing aluminum and copper heat exchangers for years. Because UAM is a hybrid process, all of the flow paths printed into our parts are CNC milled allowing for high accuracy and great surface finish. Recently we finished up a large program for NASA that sought to improve the state of the art with embedded channels.
In our last post, we talked about using custom cut insert panels to span large unsupported areas. One problem with that method is that it inherently leaves an unbonded zone where the edge of the plate meets the edge of the step machined in the part (as seen below).
Another technique that we recently investigated, was using Friction Stir Welding to seal this vertical ‘crack’. Since our SonicLayer machines are of a hybrid design, we already have a high strength spindle in the machine. To FSW the plate outline, and thus seal the ‘crack’, we simply need to do a tool change and raster the pin tool along the path. The picture below shows a square insert that has been friction stir welded. After welding, the CNC mill comes in to machine the area flat and we continue to weld material. This technique will allow UAM to build large unsupported regions and have a final part that is 100% and welded with solid state welding processes.