Geometric measurement of
the ceramic layers made by
the robocasting technique
Robocasting is a first-generation extrusion additive manufacturing method
for ceramic-based materials that builds finished parts in successive layers. It
has the advantages of being easy to process and economic and works with awide range of materials. Robocasting is promising on produce piezoelectric
sensors, ceramic lattice filters or ceramic lattice structures such as custom
bone implants. Conventional methods, such as SEM, can be applied tomeasure some geometric information on sintered parts, however, as-printed
ceramic layers are difficult to measure by conventional methods.

The Worcester Polytechnic Institutewas founded on 1865 and isfocused on the instruction andresearch of applied sciences andengineering. The authors of thisstudy are: Zhaolong Zhang and Dr.
Christopher Brown.

In this study, a non-contact 3D surface metrology confocal microscopy(S neox, Sensofar, Barcelona) is used to measure heights, and volumes ofsingle layer ceramic paths, and heights of two-layer printed ceramic parts.

CASE STUDY PRECISE THICKNESS MEASUREMENTS OF THIN SiO2 MASK FILMS

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Figure 1. a) Single-layer path with a length of 20 mm and a 2 mm gap between nearby paths.
b) Two-layers print with a length of 20 mm, a 2 mm gap between nearby paths.

Figure 2. A schematic of the single-layer pattern.

Figure 3. A schematic of the experiment for measuring heights of two-layer parts.
2CASE STUDY PRECISE THICKNESS MEASUREMENTS OF THIN SiO2 MASK FILMS

■ Measurements
The continuous confocal mode with a magnification of 5X was used to study
the single-layer path. Analogously, the continuous confocal mode with amagnification of 5X and an extended measurement of 9 fields of view wasused to study two-layer parts.
As shown in figures 4 to 7, eleven cross-sections with height, width and areas
were collected for each pattern. Averages were computed and analyzed. The
volume of each single-layer path is also calculated by the average lengthand the cross-section area.

Figure 4. Surface topography of a robocasting ceramic single-layer patternmeasured in S neox Confocal mode and with a 5X magnification.

Figure 5. 2D profile of a robocasting ceramic single-layer pattern,measured in Confocal mode and with a 5X magnification.

CASE STUDY PRECISE THICKNESS MEASUREMENTS OF THIN SiO2 MASK FILMS

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Figure 6. Surface topography of a robocasting ceramic two-layer patternmeasured in S neox Confocal mode and with a 5X magnification.

Figure 7. 2D profile of a robocasting ceramic two-layer pattern,measured in Confocal mode and with a 5X magnification.

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CASE STUDY PRECISE THICKNESS MEASUREMENTS OF THIN SiO2 MASK FILMS

■ Conclusions
With the help of 3D optical profilometer Sensofar S neox in the confocalmode, we successfully measured geometric parameters of as-printed ceramicparts without sintering them. By avoiding impacts from sintering process,these dimensions can be used as database to predict and improve theaccuracy of robocasting processes.

CASE STUDY PRECISE THICKNESS MEASUREMENTS OF THIN SiO2 MASK FILMS

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