On surface structure characterization and application on additive manufacturing
Countless industrial applications over the past decades have indicated the increased need to relate surface texture to surface function. The fast-growing industry of additive manufacturing admits the surface roughness as one of the main challenges. It makes the need for quantitative and qualitative control of surfaces and an understanding of surface measurements and analysis more important than ever. Surface metrology covers the questions related to surface measurements, its analysis, representation, and interpretation. Despite the long experience of surface measurements, there are still a lot of open questions.
The aim of this thesis was to investigate the interaction between surfaces and the optical metrology of surfaces’ topographical properties’. More precisely this thesis includes an examination of tools and methods for quantitativeand qualitative characterization of surfaces measured by optical instruments in particular coherence scanning interferometry. Further, those methods and analysis were used on additively manufactured surfaces.
The contribution of this thesis lies in the intersection of the fields of characterization, manufacturing and function.
First of all, the use of power spectral density (PSD) analysis in this thesis proved it to be a powerful analysis tool for identification of differences and equalities between instruments measuring similar topographies. Besides PSD analysis together with surface roughness parameters were used for comparison of surface topography and its characterization.
Secondly, texture analysis of the surfaces used in dental industries, piston rings and selective laser melting surfaces showed that thus the effectiveness of surface parameters representing surface topography depends on the specific measurement range.
Finally, research was focused on the characterization of additively manufactured surfaces. The surfaces produced by fused deposition modelling (FDM) and by selective laser melting (SLM) manufacturing processes were studied. An areal model with the aim to produce a visual representation of FDM surfaces was built based on the ellipse geometry. The model was validated by comparison with the areal measurement using surface parameters and PSD analysis. Analysis of surface topography produced by SLM techniques was used to compare heat transfer and flow rate of cooling channels with different roughness.
This thesis, through the use of a combination of analysis tools thus sheds new insights into the field of additive manufacturing, the virtual representation of surfaces and connection between surface functional performance and choice of characterization linked both to measurement techniques and evaluation methods.
surface texture parameters.
fused deposition modelling
power spectral density
coherence scanning interferometer
selective laser melting