Measuring procedures for surface evaluation of additively manufactured powder bed-based polymer and metal parts

Abstract

Powder bed-based additive manufacturing has become increasingly important for industrial applications. In the light of this, qualitative considerations such as the geometrical accuracy, the resulting mechanical properties, and the surface quality of additively manufactured parts must be taken into account. Optical measuring techniques such as confocal laser scanning microscopy, fringe projection and focus variation as well as profilometers are evaluated here, to determine the surface quality of powder bed-based manufactured parts. Even though these surface evaluation methods are established commercially, no standardized measuring procedure has yet been established. Within an experimental study the validity and accuracy of surface measurement methods are evaluated below, taking the limitations of each measurement system and the comparability of areal surface textures into account. The examinations are carried out with the powder materials EN-AW2024, Ti-6V-4Al and PA12, which are processed by electron beam melting, and laser beam melting of metals and polymers. Guidance for a consistent and comparable surface evaluation is thereby provided.

Effect of Cut-Off, Evaluation Length, and Measurement Area in Profile and Areal Surface Texture Characterization of As-Built Metal Additive Manufactured Components

“…The difficulties and the suitability of the focus variation technique were highlighted. The ability to separate single powder particles using material ratio and spectral density analysis was also highlighted [15]. The difference in surface texture results due to changes in measurement area is evident in the as-built and postprocessed conditions [16].…”

Algorithmic detection and categorization of partially attached particles in AM structures: a non-destructive method for the certification of lattice implants

“…“As shown in figure 2 the surface texture may be influenced by partially adhering powder particles . In the worst cases, a single layer of unmolten particles may influence surface roughness.” (Heinl et al , 2020). “In order to provide information on the tissue-implant interface for Gyroid-based implant design, the numbers of partially attached particles from each image were quantified via a custom-developed image recognition code.” (Yang et al , 2019).…”

“…“As shown in figure 2 the surface texture may be influenced by partially adhering powder particles . In the worst cases, a single layer of unmolten particles may influence surface roughness.” (Heinl et al , 2020).…”

Influence of Ring-Shaped Beam Profiles on Process Stability and Productivity in Laser-Based Powder Bed Fusion of AISI 316L

“…A 3D profilometer (Keyence VR-3100, Ōsaka, Japan) is used to measure the roughness of the multi-track segments via fringe projection. The optical measurement enables a local description of the whole topography and thus the evaluation of the associated roughness values S i [29]. In this study, the areal arithmetic average roughness S a (according to DIN EN ISO 25178-2 [30]) is used for roughness determination.…”