Fused deposition modeling (FDM) is one of the most common forms of additive manufacturing (AM). It is ideal for prototyping, modeling and low-volume manufacturing. Unlike other 3D printing processes, such as SLA, SLS and DMLS, that use powder and resin materials, FDM process filament materials. For this reason, it is a unique process to design for.
This article offers a comprehensive guide to the best design practices for FDM 3D Printing. It includes an overview and considerations of the process, design guidelines, and a summary of best design practices.
In FDM, a thin polymer-based filament is extruded through a heated nozzle, which melts and deposits material layer by layer to form the final object. The process is compatible with a wide range of filaments, proving material flexibility.
Disadvantages of the FDM Process
Characteristics of FDM 3D Printing
| Maximum Build Size | 800 x 800 x 550 mm |
|---|---|
| Resolution | ±0.3mm |
| Dimensional Accuracy | ±0.3% (with a lower limit of ±0.3 mm) |
| Common Materials | ABS, Nylon (PA), PC, PLA, TPU |
| Surface Structure | Rough. Visible layer lines |
| Support | Required |
Overhangs
Issues with overhangs are one of the most common FDM print-quality problems. Depending on the material, an overhang can usually be printed up to 1.2mm in length and up to 45° without compromising quality. Anything above these limits will require support.
Unsupported Walls
With FDM, unsupported walls—connected to the rest of the print on less than two sides—are at a high risk of warping. To avoid this, they should be at least 1.2mm thick.
Supported Walls
These walls are connected to other structures on at least two sides (so they have a very low likelihood of warping). Supported walls should be designed with at least 1.0mm thickness.
Pins and Columns
Pins are tall thin features with a circular cross-sectional area. The diameter of a pin can be designed to 0.8mm, but even then, risk breaking. The minimum reliable pin diameter is 1mm.
Mating Parts
For FDM parts, adequate clearances must be designed between mating parts to prevent the assembly from sticking together. To avoid this, models must be designed with a minimum clearance of 0.5mm.
Embossed Details
Embossed features must be designed using a minimum height, otherwise, it will not appear visible. Such features should be designed at least 0.3mm in height.
Engraved Details
Engraved features must be designed using a minimum depth and width, otherwise, it will not appear visible. Engraved details should be at least 0.5mm deep and 0.5mm wide.
Summary of Best FDM Design Practices
| Overhangs | Up to 1.2mm in length and up to 45° |
|---|---|
| Unsupported Walls | At least 1.2mm thick |
| Supported Walls | At least 1.0mm thick |
| Pins | Minimum reliable diameter is 1.0mm |
| Mating Parts | Minimum clearance of 0.5mm |
| Embossed Details | Minimum height of 0.3mm |
| Engraved Details | Minimum depth of 0.5mm; minimum width of 0.5mm |
Use the 3D Printing Design Guidelines to help design your parts for machining then export your 3D CAD files into an STL format. Once ready, upload your files here to get an instant quote. Please keep in mind that these are general guidelines, and your specific part geometry and manufacturing requirements may vary depending on different factors such as material choice. If you have any questions, you can get contact with us at info@hlhrapid.com or through our get in touch form for more information.
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