Abstract
All additive manufacturing processes have a characteristic ‘staircase’ layering effect at the boundaries, as this process family fabricates components by stacking layers upon each other. This effect is noticeable at shallow angles and where there is significant surface curvature. Measuring the surface roughness from virtually modeled beads of an additive manufactured product helps to have an initial estimation of the surface quality during process planning. In this paper, three techniques are developed to measure the profile surface roughness from an ‘as-built’ CAD model generated from theoretical bead geometries. Two CAD files are needed as inputs: a model of the ideal part geometry and the model created based on the bead geometry, percent bead overlap, and the fill strategy. Developed solutions are projection, projection normal-line distance, and elongation method.
The results are verified by analytical calculations with less than one percent variation. The samples include flat faces, a curved surface, and an S shape (a double arc). Sensitivity studies for evaluation length are conducted as well.
Estimation of the surface roughness values before a component is being built will help designers to evaluate how much material stock is needed to be added if subsequent machining processes are required. Therefore, it is anticipated that this research will assist process planners in developing their desired build solutions for both AM and hybrid manufacturing.
