Austria: SLA 3D printing of high-precision glass ceramic parts

China3D printingNet, May 4, Austrian researchers have explored photolithography-based ceramic manufacturing (LCM) technology in the recently published “3D lithography additive manufacturing of high-precision glass ceramic parts”. The author focuses on glass ceramics and seeks new ways to optimize applications such as dental substitutes.

now,3D printingIt is often associated with the use of ceramics and provides innovative advancements in dental and orthodontic laboratories. Understandably, crowns, bridges and implants must be manufactured with the highest precision.
Excellent mechanical properties are essential to create aesthetics and proper fit-leading industrial users to adopt many different types3D printing:

.FDM 3D printing

.Selective Laser Sintering (SLS)

.3D printingAnd Stereo Lithography (SLA)

. Lithography-based ceramic manufacturing (LCM)

In this study, the researchers chose LCM because it can create highly filled and photopolymerizable ceramic pastes, as well as dense parts with “excellent” material properties. Several steps are involved:

.
Develop and adjust the slurry according to the type of additive manufacturing

.Making a 3D composite

.Support structure is removed

.Heat aftertreatment begins

Material properties of different ceramics achieved through lithography-based ceramic manufacturing (LCM)

Several different scanning methods are used to assess the accuracy of parts, including:

• Optical scanner

• Tactical Scanner

•Micro CT



The main component of the slurry.

The slurry base material consists of the following substances:

.
Monomer composition and solvent

.Photo absorber

.Photoinitiator

.Ceramic filler with solid content greater than 50 vol%



Molar crowns with different support designsstl file(From left: “Cross”-support design A, “star”-support design B).

stl file
Crowns of the molars, marking the different areas where the supports are attached” alt=”.
stl file

Crowns of the molars, mark the different areas where the supports are attached” width=”620″ height=”193″ />

.stl fileCrowns of the molars, marking the different areas where the supports are attached.

The supporting structure is a key part of the structure, which can be used for drape printing and prevent warping. The researchers printed a sample of the molar crown for the study, which provided cross-support for the occlusal surface of the crown. Another type of star-shaped structure provides additional support on the oral side. Avoid using the tooth tip, the distal and mesial surfaces, and the gap between the crown and the inner surface of the core as support locations.
To digitize the samples, the research team used a variety of scanners and 3Shape software. Adjust the star shape according to the light absorber and printing parameters, and further consider the possibility of adjusting the resolution by the thickness of the wet layer in the material barrel.

Siemens star, 9 mm in diameter: (a) for researchstl file; (B,c) SEM images of the green body.

The scientists made a sample of the crown and star support structure for comparison, and pointed out that different techniques produced different results.
The researchers explained: “Due to the reflection and translucency of ceramics, challenges were encountered in replicating real surfaces, which resulted in the so-called’orange skin’ effect using the 3Shape D810 infrared scanner.”



A crown images obtained with different scanning methods.

Connect the LCM-treated tooth crown to the original.stl fileCompare it because it has been rescaled using x, y, and z factors. The researchers pointed out that the best results can be obtained through micro-CT scanning, so they also use it for subsequent analysis. The analysis showed that during the sintering process, the crown with star support was deformed and did not provide enough support. Further improvements have brought higher accuracy, no warpage, and the color scale can be reduced to minus 80 µm to plus 80 µm.


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Procedure for the accuracy of the crown” alt=” evaluation
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Procedure for the accuracy of the crown” width=”620″ height=”553″ />

evaluate3D printingProcedure for the accuracy of the crown (a) CAD reference model, (b) CAD reference model prepared, (c)3D printingMicro-CT scan of the sintered molar crown, after removing the “star” support (d) use GOM Inspect to compare the CAD reference model and the 3D surface model.

The researchers said: “By comparing all test support types using statistical information, you can see the improvement in dimensional accuracy. This is achieved by putting all the analyzed crowns on the same original file and performing surface comparisons. Afterwards, adjust The deviation scale is to highlight only the relevant measurement values ​​and display all colors in the false color map. Finally, the maximum and minimum deviations of the color false scale are used to measure the scale in Figure 9 (below).

stl file“alt=” Use GOM Inspect to compare 3D surface models (sintered molar crowns with “milling” support, design C) andstl file“width=”620″ height=”541” />

Use GOM Inspect to compare the 3D surface model (sintered molar crown with “milling” support, design C) andstl file.

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