Additive manufacturing enables the creation of complex and precise structures, providing users with unparalleled design freedom. According to the latest 2023 Hubs report, FDM printing technology (also known as Fused Deposition Modeling) is the most popular 3D printing process due to its ease of use and user-friendliness.
△71% of participants in the Hubs report said they will 3D print more parts in 2022 than the previous year
However, as with any printing method, errors can occur during the fusing layering process, resulting in unattractive or unusable prints such as warping, stringing, warping, and more. This installment focuses on how to solve another common problem that can arise during FDM printing: over-extrusion.
Overextrusion occurs when a 3D printer's extruder deposits too much material, often causing the edges of the printed part to bulge and bulge. Additionally, the individual layers may not be uniform in thickness, resulting in uneven and unattractive surfaces. Excessive material flow can even lead to nozzle clogging over time. In the following, we list possible causes of over-extrusion and provide corresponding potential solutions to avoid this error in future prints.
△Over-extrusion manifests itself as overblown part edges and a lack of precision and detail (Photo credit: Creality)
In most cases, over extrusion can be attributed to too high a print temperature. When the temperature setting on a 3D printer is too high, the filament melts too quickly and the extruder loses control of the flow rate. Therefore, a higher temperature setting produces a more fluid extruded material. In this case, the cooling fan cannot cool the filament quickly enough, resulting in uncontrolled and excessive flow of material through the nozzle. Another contributing factor to overextrusion is the diameter of the filament used. If the diameter of the filament is smaller than the nozzle, it may pass through too quickly, causing over extrusion. Likewise, incorrect filament diameter settings in the microtome software can result in incorrect flow rates and over extrusion.
The flow rate represents the amount of filament extruded per second, which is determined according to factors such as printing speed, nozzle size and layer height. When the flow rate is set too high, too much filament is pushed through the nozzle, causing over extrusion. Now that you understand the possible causes of this type of 3D printing error, let's explore the options available to fix it and prevent it from happening again.
Reduce print temperature to prevent over extrusion
In order to solve the problem of over extrusion, it is recommended to check the printing temperature first and reduce the temperature if necessary. It is important to note that the optimum printing temperature may vary depending on the type of filament used. For example, when printing with PLA, the temperature range should generally be between 190°C and 220°C, while ABS can be printed in the 230°C to 260°C range, and PETG typically requires temperatures between 210°C and 250°C . It is recommended to gradually reduce the print temperature in 5°C increments, making sure not to reduce the temperature too much as this may result in under-extrusion resulting in insufficient material flow.
Calibration Filament Diameter
Another method is to calibrate the flow rate to the exact diameter of the wire. Most filaments on the market are available in standard sizes such as 1.75mm, 2.85mm or 3mm. It is very important to ensure that the filament size is set accurately in the print settings. While specifying the manufacturer's specifications is usually sufficient, if the problem persists, manual verification of the wire diameter may be helpful as there may be slight deviations from the specifications. Using a digital caliper, you can measure the diameter at five different points and calculate the average. This measurement should then be entered into the filament settings (or machine parameters) in the slicing software. The diameter you measure may vary slightly from manufacturer specifications. For example, a wire marked 2.85 mm may have a diameter of 2.84 mm, which may affect flow.
△Example of overextrusion. Photo Credit: Ultimaker Community
Adjustment of extrusion ratio (flow rate)
The extrusion multiplier setting controls the flow rate of the filament during printing. Typically, the default value for extrusion multiplier is set to 100%. However, to address overextrusion, the value can be gradually decreased in increments of 2.5% to 5%. It is important to test and evaluate the impact of each adjustment with test prints.
Alternatively, is there a more precise way to determine the appropriate extrusion multiplier adjustment. First measure and mark along the filament 120mm from the top of the extruder. Then, instruct the 3D printer to extrude a 100 mm filament. After extrusion, measure the remaining filament from the top of the extruder to the marked line. For example, if you find that you are extruding 104mm of filament, you can reduce the flow rate by 4%.
It is worth noting that for different materials, the recommended extrusion ratio may be different. For example, the popular slicer software Simplify3D recommends using an extrusion factor of 0.9 (90%) for PLA, while for ABS it is recommended to keep values closer to 1.0 (100%).
nozzle care
It is important to keep the nozzle clean and undamaged at all times. Check the nozzle regularly for signs of wear, especially when using abrasives such as filaments containing wood, metal or carbon fiber particles. Over time, the nozzle may wear, causing its diameter to increase. If you notice this wear, be sure to replace the nozzles to ensure the best printing results.
△Nozzle diameter comparison of worn nozzle (right) and new nozzle (left). (Photo credit: Stack Exchange)
By implementing a few key strategies, we can effectively counteract over-extrusion issues that may be encountered during printing. These strategies include lowering the build temperature, accurately calibrating filament diameters, adjusting extrusion multiples, and properly maintaining dies. These measures above can ensure better printing results and minimize the occurrence of over extrusion.
