At Xometry one of the most common problems we face with additive manufacturing is the risks related to thin walls and fragile features. We conducted a wall thickness stress test in our various printing processes to best understand the limitations of each process and made note of the results. We hope that our findings will prove to be insightful and help you refine your part designs for additive manufacturing! In addition to the results seen here, be sure to check out our design guides for further notes, design tips and recommendations for each process!
The Test Parameters
Our stress test starts by printing the same part in each of our main printing processes and materials. For this test, the following processes and materials were chosen: SLS Nylon, PJ3D Rigid Photopolymer, FDM ABS (0.010" Layer Height) & FDM ABS (0.013" Layer Height). We printed ABS in two layer heights as layer height can vary in the FDM process; larger parts are typically printed with a 0.013" layer height.
We designed the stress test part to push the limits of the machines and printing processes. The part contains a mix of knife edge features, walls and text at varying sizes and thicknesses. There are other features on the part which are designed to result in thin walls or fragile features that will consequently have high risk for failure.
SLS Durable White Nylon
Observations:
- Knife Edge Features: Overall we can see the knife edge points partially resolved. There is some noticeable warping on the thinnest knife edge (Marker 1 in the photo) which is expected with such a thin and comparatively tall feature. The tips of the knife edges appear to be cut-off due to the limitations of the process (Marker 2).
- Thin-Wall Features: Generally SLS was able to resolve most of the thin walled features which come down to 0.25mm in thickness (thru-hole near edge, bottom of spherical pocket, rectangular wall array). Although these features resolved, we would not recommend features this thin as they will be inherently fragile.
- Text Features: Overall the text resolved nicely, however you will notice as the text gets smaller, the sharpness seems to diminish as well. This is attributed to over-sintering combined with the tiny feature size (Marker 3).
PolyJet 3D Rigid Photopolymer (Semi-Gloss Black) Results
Observations:
- Knife Edge Features: Overall the knife edge features did not survive the print and post processing requirements for PJ3D. The thinner the base of the knife edge, the shorter the features ultimately ended up being (Marker 1).
- Thin-Wall Features: The thin wall features also did not have much luck surviving the PJ3D process. Walls below 1mm thick were blasted away during support removal (Marker 2). Interestingly, the 1.5mm thick wall only partially survived, however the 1mm thick wall stood in place. The thin wall of the thru-hole was blown out during post processing, as seen on Marker 3.
- Text Features: The text came out surprisingly well with little to no damage during post processing. While the results came out well in this test, generally small text runs the risk of being blown away or damaged due to the pressurized water jet used in support removal. The thicker the text is, the less likely it is to become damaged or blown away during post.
FDM ABS-M30 Dark Gray (0.010" Layer Height) Results
Observations:
- Knife Edge Features: The knife edge features partially resolved in this test. Similar to PJ3D, the thinner the base of the knife edge, the shorter the features ultimately ended up being (Marker 3).
- Thin-Wall Features: Most of the thin walls came out, however the 0.25mm thick wall was much too thin and it simply was not printed at all. This demonstrates how smaller features can become "sweated out" in the FDM process (Markers 1 & 2). Due to the thin wall of the thru-hole, only 1 contour could be generated to make the feature. This 1 bead thick wall will be inherently fragile (Marker 4).
- Text Features: The text struggled to resolve in this test. As the text becomes smaller and thinner, less tool paths can be generated and thus, certain text features only partially resolve or do not print at all (Marker 2).
FDM ABS-M30 White (0.013" Layer Height) Results
Observations:
- Knife Edge Features: Similar to the 0.010" layer height test, the knife edges partially resolved. As the base of the edges gets smaller, the resulting height is lower. The height of each knife edge ended up being cut shorter compared to the 0.010" layer height due to the larger layer height and bead size (Marker 3).
- Thin-Wall Features: Only half of the thin walls printed; the 0.25mm & 0.5mm thick wall were too thin and they were not printed at all (Marker 1). The thin wall at the thru-hole ended up with odd bulging which caused the feature to be non-concentric. Any thinner and the machine would have likely not made a tool path here at all (Marker 4).
- Text Features: Even less text resolved due to the larger bead size at the 0.013" layer height. As the text becomes smaller and thinner, less tool paths can be generated and thus, certain text features only partially resolve or do not print at all (Marker 2).
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