Additive Manufacturing and 3D Printing

Bruker’s 3D Optical Metrology technology drives optimisation of process control and new product development in Additive Manufacturing and 3D printing. We exploit interferometry methods proven for fast repeatable metrology on even the smoothest of microstructure finishes high-speed measurement of shape, forms and roughness. Transparent and opaque surfaces can be measured at reflectivities up to 99% following each process stage to:

  • Quantify and optimise fusion effectiveness — correlating laser power, layer bed thickness, and scanning speed to surface morphology changes
  • Optimise laser power and bed thickness — linking layer to layer roughness parameters to adjacent layer spacing
  • Identify printing defects from roughness parameter deviation from expected layer thickness
  • Characterise shape and critical dimensions, and identify mixed powder alloys by spatial variation in colour
  • Correlate advanced roughness parameters with sandblasting, polishing and coating settings

Case Study: Qualifying process differences between Inconel & Aluminium powder SLM manufactured rings

Selective laser melting techniques (SLM) require adjustment of laser beam power, spot size and scanning speed to ensure adequate melting of the complete bed layer in Additive Manufacturing (AM). Process parameters are highly dependent on powder chemistry. Bruker’s Contour 3D optical profilers enable process optimization through complete analysis of 3D surface microstructure parameters.

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Figure 1: Extraction of shape, waviness and roughness on Inconel powder manufactured ring by LSM. Righthand image shows corresponding part made from aluminium.

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Figure 2: 3D surface morphology of comparison between Aluminium and Iconel manufactured rings

Figure 2 identifies key differences between SLM manufactured ring parts using Inconel 718 and Aluminium powders. Aluminium still exhibits unmelted or partially melted particles resulting from too low laser power or too fast laser scanning, while Inconel reveals a uniform melting front confirming optimised laser settings.

In addition to providing a powerful 3D visualisation of morphology differences, the Contour optical profiler quantifies and ranks process quality through advanced roughness S parameters from ISO norm 25178. This drives iterative optimisation of process conditions. The following specific parameters best discriminate between Al and Inconel based process:

  • Ssk (Skewness) quantifies degree of symmetry above/below the mean plane characterizing the number of extreme peaks or valley structures. Zero value stands for perfect symmetry while a negative value indicates a higher number of cavities/pores and a positive value emphasizes a predominance of unmelted particles
  • Sdr expresses how corrugated/porous the surface is
  • Ssc is the Mean Summit Curvature for the various peak structures revealing presence of aggregated or partially melted particles
  • Sm represents the mean spacing between asperities or spikes


The surface from the Inconel ring is indeed smoother (Figure 2) due to better optimised process conditions delivering improved fusion of the particle bed. Specifically, it exhibits (a) lower corrugation evidenced from Sdr differences, (b) a flatter surface with longer radius of curvature proved by 60% higher Ssc, and (c) contains longer spacing between asperities/spikes proved by the 57% larger Sm value.

Bruker’s Vision64 Map software enables immediate databasing of all those key roughness parameters making it possible to build custom experimental models. Modelling then provides a faster time to accurate results without blind trial & error process changes.

Download the case study PDF.


Case Study: Identifying causes of failure in 3D Print PEEK lab-on-chip components

Bruker’s Contour Optical Profilers were used to optimise manufacturing processes and quality control of PEEK 3D printed parts used for lab-on-chip. Figure 3 compares the layer to layer morphology changes between correctly performing and defective parts.  Roughness parameter “Sal” quantified the texture uniformity between failed and passed parts. Sal (auto-correlation length) measures the distance over the surface for the new location to have minimal correlation with the original location. The Sal quantifies the average periodicity of layer to layer, emphasizing the process deviation in layer to layer spacing. The NOK (failed) part clearly shows fusion/merging between layers which indicates too high processing temperature. The OK (passed) part exhibits a regular uniform pattern. 

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OK / Sal = 77µm

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NOK / Sal = 88µm (+14%)

Figure 3: 3D morphology Comparison of 3D printed PEEK lab-on chip components; Parts Courtesy Denis Dowling, University College Dublin

 

In summary, Bruker’s Contour platforms have a unique portfolio of complimentary 3D Optical metrology techniques combined with automated analysis and databasing. This enables immediate identification of issues with Additive Manufacturing processes and accelerates R&D for next generation high performance structures. 

Download the case study PDF.

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