6 Finished parts
The advent of AM was essentially the improvement of RP to produce a functional part. RP engineers were essentially only interested in the shape, form and aesthetics of their products. If function is to be considered, factors like microstructure, porosity, surface crack initiation sites, variations in density and residual stress become important.
These topics are being researched within universities and by machine manufacturers, and the issues are a long way from being solved. An appreciation of these issues, but not necessarily knowledge of how to solve them, is important.