What is the Maximum Volumetric Speed?
Maximum Volumetric Speed is the highest rate at which a 3D printer can extrude material while still maintaining good print quality. It is measured in cubic millimeters per second (mm³/s) and helps define the printer’s extrusion limits.
What affects the Maximum Volumetric Speed?
The Maximum Volumetric Speed depends on several factors:
- Filament Type: Different materials melt and flow differently. For example, PLA has a higher volumetric speed than TPU because it melts and extrudes more easily.
- Extruder Performance: A powerful extruder can push filament faster without slipping.
- Nozzle Specifications: Larger nozzles allow more material to pass through, increasing the possible speed. However, they also require more heat to maintain proper extrusion.
- Hotend Temperature & Efficiency: The heater must provide enough energy to fully melt the filament before extrusion. A higher Maximum Volumetric Speed requires efficient heat transfer.
Why is Maximum Volumetric Speed Important?
- If you exceed the Max Volumetric Speed, the extruder may struggle to push filament, causing under-extrusion (gaps, weak layers, or missing material).
- If you stay within the Max Volumetric Speed, prints will have consistent flow and good quality.
How is the Maximum Volumetric Speed Used in Slicing?
- Bambu Studio and other slicers allow setting a Max Volumetric Speed limit to prevent pushing filament too fast.
- This setting helps determine the maximum print speed based on layer height and extrusion width.
- If you increase speed beyond what the Maximum Volumetric Speed allows, the slicer will automatically reduce print speed to avoid extrusion issues.
Are you curious about how the maximum volumetric speed translates into the maximum printing speed?
Today, we focus on calculating the max achievable print speed using a common volumetric rate of 22 mm³/s for Bambu PLA Matte filament.
Step 1: Calculate the Extruded Filament’s Cross-Sectional Area
Print Head Cross-Sectional Area (example from Slic3r)
Using a 0.4 mm nozzle, 0.2 mm layer height, and 0.42 mm line width:
The cross-section of the extruded material can be approximated as semicircular areas on both sides plus a rectangular area.
Side areas (approximated as a circle):
Middle rectangular area:
Total cross-sectional area:
Step 2: Calculate Maximum Print Speed
Now, we use the maximum volumetric speed (MVS) (22 mm³/s in this example) to calculate the fastest possible print speed while maintaining proper extrusion.
Based on the above calculations, we obtained a maximum printing speed of approximately 290 mm per second for a volumetric rate of 22 mm³/s. Of course, this is only a rough estimate.