Comment Seeing is Believing (Score 1) 74
After using industrial CT to review hundreds of "printed" Ti parts, the prior above comment regarding differentials from batch to batch could not be more correct. The issue is caused by a lack of control over the purity of the powder material. All it takes is are a couple of tiny impure grains, which result in a 'pop corn' effect during the processing. Each layer is not visible or inspected, so the defect becomes encased by surrounding melted material and the resulting void is now invisible. If each part is CT scanned, and qualified showing no porosity in critical structural areas, this may be satisfactory for non structural parts. The downside is CT inspection is time consuming (10-15 min per part); the upside is a diminished skilled worker demand. At a recent symposium showcasing all the major 3D metal print firms along with the major aerospace fabricators, curiously there were NO Quality or CT firms invited or exhibiting. Not being a conspiracy theorist, but it does make one want to say hmmmm.
We now can conduct virtual structural analyses on the actual geometry of the printed metal part, defects and all, using the CT voxel based dataset. Doing porosity analyses is completely automated as well on the same dataset. This is a young industry. Save your $$ fabricating non structural parts til the process track record and material control is proven to be magnitudes greater than I have seen so far for mission critical parts. Printed metal biological replacement parts such as hip sockets, joints, knees, and spinal parts are ideal for this young industry in that the force loading is quite a bit less, and can tolerate porosity; wing spar supports, turbine blades, engine mounts, NFW.