Surface characterization in Additive Manufacturing - An empirical study of angular dependency

Abstract: Surface roughness is one of the main challenges for the growing industry of additive manufacturing. Not only are surfaces rougher than on components produced by conventional means, but there is also a great variation within a single component as well. In this thesis, we have studied the surface roughness of AM components using focused variant microscope and X-ray computer tomography. This is used to find a suitable test component and a measurement protocol to accurately understand and predict the surface roughness produced under specific conditions. The main focus has been on how the surface roughness of the external surfaces varies with the angle of the surface. It has been shown that the roughness does depend on the angle of the measured surface and that it is possible to simulate this using simple model, and the measurements necessary could be done in an afternoon. XCT gave an indication that it might be possible to determine the internal surface by measuring the external, however, this we were unable to confirm. From these results the need for a new notation for the roughness parameters became evident and hence we have found a suitable notation which is presented here. The new notation will hopefully make it easier to discuss and communicate which roughness and surfaces that are alluded. This new protocol will give a fast method for understanding and predicting the surface roughness of a new machine or a new set of settings.