Very interesting video – thanks so much. The idea of combining CNC with metal printing is excellent because you have to treat the very poor surface finish in any parts that have working interfaces. In the SLS nylon which I use the surface granularity is about 0.1mm – think 300 grit sandpaper, or 10-20 times worse than injection moulding. However the absolute accuracy and repeatability is better than any casting, so the amount of metal to be removed is far less. Printing and machining in the same set up potentially removes a host of errors.
Of course this all relies on the belief that the fusing of the powder is completely homogenous – that there are no ‘soft spots’ hidden inside the material. I don’t know how you guarantee that, except by relying on the principle that if it’s fused on the outside, then the interior must have been hotter and therefore completely fused. Perhaps.
In general, directed energy deposition achieves densities on par with forging. Part resistance will also be conditioned by post deposition heat treatment.
Nasa prints the first copper rocket engine liner, with built-in cooling channels:
https://www.nasa.gov/marshall/news/nasa-3-D-prints-first-full-scale-copper-rocket-engine-part.html
