5 Mistakes Engineers Make When Designing Parts for 3D Printing
Avoid costly rework and wasted materials by learning from these common 3D printing design pitfalls.
Ignoring Minimum Wall Thickness
One of the most frequent errors is designing parts with walls that are too thin for the chosen 3D printing technology. Insufficient wall thickness leads to weak, fragile parts that are prone to breakage during printing or post-processing. Each 3D printing process has its own minimum wall thickness requirements. For example, Selective Laser Sintering (SLS) typically requires thicker walls than Stereolithography (SLA).
Before you start designing, consult the manufacturer’s guidelines or material data sheets for the specific printer and material you intend to use. A general rule of thumb for Fused Deposition Modeling (FDM) is to aim for a wall thickness of at least 1mm. For SLA and SLS, check the manufacturer’s guidelines, but 0.8mm is a good starting point. Consider the function of the part. If it needs to withstand significant stress, increase the wall thickness accordingly. Use design for manufacturing (DFM) principles to ensure your part meets these requirements from the outset. Failing to account for minimum wall thickness can result in print failures, dimensional inaccuracies, and a compromised final product.
Underestimating Overhang Issues
Overhangs, sections of a part that extend outward without support from below, are a common source of 3D printing problems. While some overhangs can be printed successfully, exceeding the printer’s capabilities will result in sagging, warping, or even complete print failure. The severity of the overhang issue depends on the printing technology, material, and printer settings. FDM printers are particularly susceptible to overhang problems, as the extruded material needs a solid foundation to adhere to.
To mitigate overhang issues, consider these strategies: Design parts with self-supporting geometries whenever possible. This might involve adding fillets, chamfers, or support structures directly into the design. Orient the part in the build volume to minimize the number and severity of overhangs. Use support structures generated by the slicing software. Experiment with different support settings to find the optimal balance between support strength, ease of removal, and surface finish. Be aware that support removal can leave marks on the finished part, so minimize their use in cosmetically critical areas. Angles greater than 45 degrees from vertical often require supports.
Ignoring Tolerances and Clearances
3D printing is not a perfectly precise manufacturing process. Parts will have dimensional variations due to material shrinkage, thermal expansion, and printer calibration. Failing to account for these variations can lead to parts that don’t fit together properly or function as intended. Tolerances define the allowable variation in a dimension, while clearances define the space between mating parts.
When designing parts that need to fit together, specify appropriate tolerances and clearances. Consult the manufacturer’s guidelines for the achievable tolerances of the chosen 3D printing process and material. As a starting point, consider a tolerance of +/- 0.1mm for critical dimensions. Increase clearances between mating parts to allow for dimensional variations. A clearance of 0.2-0.5mm is often sufficient. Consider the impact of post-processing steps on dimensional accuracy. Sanding or painting can alter the dimensions of the part.
Neglecting Material Properties
Each 3D printing material has unique properties, including strength, stiffness, heat resistance, and chemical resistance. Choosing the wrong material for the application can lead to part failure or poor performance. For example, a part made from PLA (polylactic acid) will not be suitable for high-temperature applications, as it softens at relatively low temperatures. Similarly, a part made from a brittle material like resin may not withstand impact loads.
Carefully consider the functional requirements of the part and select a material that meets those requirements. Consult material data sheets to understand the properties of different materials. Consider factors such as tensile strength, elongation at break, flexural modulus, and heat deflection temperature. If the part needs to withstand specific environmental conditions, such as exposure to chemicals or UV light, choose a material that is resistant to those conditions. Don’t assume that all 3D printing materials are created equal. Research and test different materials to find the best fit for your application.
Overcomplicating the Design
While 3D printing offers unparalleled design freedom, it’s important to avoid overcomplicating the design. Complex geometries can increase printing time, material usage, and the risk of print failure. They can also make the part more difficult to post-process and assemble. Before adding unnecessary features, ask yourself if they are truly essential to the function of the part.
Simplify the design by removing unnecessary details, such as sharp corners, small holes, and intricate patterns. Consider using simpler shapes and geometries that are easier to print. Break down complex parts into smaller, more manageable components that can be printed separately and then assembled. This can improve print success rates and reduce material waste. Use infill patterns strategically to reduce material usage and printing time without compromising part strength. Optimize the design for the specific 3D printing process and material. What works well for one technology may not work well for another.
Key Takeaways
- 3D printing design mistakes
- DFM errors
- 3D printing design rules
- Printable part design
- 3D printing tolerances