Print Defects from FDM
3D printing print defects refer to issues or imperfections that can occur during the printing process, resulting in a less-than-desirable outcome. In this blog post, we will provide a comprehensive list of the most frequently encountered print defects in FDM printing. We will explore how these defects can affect the overall quality and functionality of the final printed object, and understand why these defects happen.
Warping:
When printing larger models, it becomes evident that while the initial layers of the part adhere well to the print bed, subsequent layers may start to curl and deform. This curling can be severe enough to result in detachment of a section of the model from the bed, ultimately leading to a failed print.
This issue is particularly prevalent when working with high-temperature materials (e.g. ASA) and when printing very large or long parts. The primary cause of this problem lies in the natural tendency of plastic to shrink as it cools.
Poor Bridging:
Bridging refers to the process of extruding plastic between two points without any support underneath. When dealing with larger bridges, support structures might be necessary, but shorter bridges can typically be printed without supports to save time and material.
During bridging, the plastic is extruded across the gap and rapidly cooled to form a solid connection. To achieve optimal bridging results, it is important to ensure that the printer is accurately calibrated with appropriate settings for these specific segments. If there is sagging, drooping, or gaps between the extruded segments, adjustments to settings may be required to obtain the desired outcome.
Unprintable Features:
The majority of 3D printers are equipped with a fixed nozzle size that determines the resolution of printed parts in the XY direction. A common nozzle size is 0.4mm in diameter, which is suitable for most prints. However, difficulties may arise when attempting to print exceptionally thin features that are smaller than the nozzle size.
One approach is to redesign the part to have thicker features by modifying the 3D model using any 3D modelling software to adjust the size of the smaller features. Thickening the thin features is necessary if the aim is to print a feature with a thickness of 0.2mm using a 0.4mm diameter nozzle. There might be an observation where this thin feature does not appear in any slicer or may not be accurately represented in the final print if the areas are not thickened to more than 0.4mm.
Poor Surface Above Supports:
Slicing softwares offers remarkable advantages through their capabilities to generate innovative support structures, enabling the creation of intricate and complex parts that would be challenging to manufacture. These support structures play a crucial role in providing a foundation for steep overhangs or areas of the model without any underlying structure.
The support structures generated are designed to be disposable and can be easily removed from the final part. One way to prevent this defect is to reduce the layer height from 0.2mm to 0.1mm. This adjustment results in the printer generating twice as many layers for the same object. Consequently, the printer can take smaller steps when creating an overhang, thereby enhancing the precision and accuracy of the printed structure.
Gaps Between Infill and Outline:
When 3D printing a part, each layer is formed by a combination of outline perimeters and infill. The outline perimeters trace the outer shape of the part, ensuring a strong and precise exterior. Inside these perimeters, the infill is printed to fill the remaining area of the layer. The infill is usually printed using a fast back-and-forth pattern to facilitate faster printing speeds. It is crucial for the infill and outline sections to merge seamlessly and create a solid bond.
Weak Infill:
The infill within your 3D-printed object holds significant significance in determining its overall strength. It serves the purpose of connecting the outer shells of your print and providing support for the upper surfaces that will be printed on top of the infill.
Certain infill patterns offer greater solidity compared to others. For instance, infill patterns such as Grid, Triangular, and Honeycomb are known for their strength. On the other hand, patterns like Rectilinear and Cubic, while enabling faster printing speeds, may sacrifice some strength in the process.
