Cura's Extrusion Multiplier
Let's take a look at Cura's extrusion multiplier, which is called flow rate. Learn what it is and how it can help fix print issues.
What Is It?
The extrusion multiplier, which is called “Flow” in Ultimaker’s Cura, specifies the rate at which your printer will extrude material. Based on the value for this setting, Cura automatically calculates how fast to move the extruder motor for certain print speeds or filament diameters.
By default, the flow rate is 100%, however not all 3D printers or filaments are created equal. You may need to adjust this value to print successfully with your specific machine and materials. Most materials use a flow rate between 90% and 110%, but you can deviate further than this range if you need to.
Generally speaking, if you’re interested in calibrating your printer and optimizing its performance, there are a number of steps you should take before starting to play around with flow rate. Before you change the flow percentage too far, check out our 3D printer calibration guide to make sure your printer is in prime condition.
If you do think the flow rate is the issue you need to address, here’s how to locate the flow settings in Cura:
- With Cura open, switch to the “Custom” settings view.
- Right-click and select “Configure setting visibility…”
- Select “Check All” (or switch your settings visibility to “Expert”) and click “Close”.
- Under the “Material” settings, you’ll now find “Flow”, with a range of sub-settings, and “Initial Layer Flow”.
Now that we know what we’re working with, we’ll dive into how to adjust these settings to rid your prints of five different issues. Note that this article focuses purely on Cura’s extrusion multiplier setting, but other slicers might have similar settings for you to experiment with.
Under-Extrusion
Under-extrusion can be directly linked to an inadequate flow rate. If you’re experiencing under-extrusion in your prints, try increasing the setting in 5% increments until you see some improvement.
Just know that you shouldn’t rely completely on flow rate. Sometimes under-extrusion can be caused by a low print temperature, too-fast print speed, or a clogged nozzle. If you increase the flow rate to over 115% with no improvement in your prints, you should revert to other fixes.
Values that are too high can force too much material through the nozzle at a time. This results in a nasty nozzle to clean or even replace.
Over-Extrusion
If you’re having the opposite problem – that is, over-extrusion – you should probably lower your printer’s flow rate. Do so in 5% increments, and check for print quality improvements.
Like with under-extrusion, adjusting the flow isn’t the only fix for over-extrusion. If you find that you keep lowering your printer’s flow rate with no print improvement, instead try lowering the print temperature or the filament diameter input in Cura.
Poor Bridging
Poor, droopy bridges can also be corrected by adjusting Cura’s flow setting. If your filament is being extruded unevenly or at an excessive rate, material flowing from the nozzle will fall into a miserable mess.
Lower your printer’s flow rate in 5% increments and keep a lookout for improvements. If you start seeing some under-extrusion, bring the rate back up and try some of our other bridging fixes.
Layer Delamination
Layer delamination is a pesky 3D printing issue, but proper calibration of flow rate in Cura can be an easy fix.
Try increasing your printer’s flow rate in 5% increments and check for better print quality. Don’t increase the rate too much, though. This can result in over-extrusion and even nozzle clogging.
If increasing the flow rate doesn’t work to fix layer separation, try applying some of our other delamination tips and tricks.
Poor Bed Adhesion
Prints popping off the plate is annoying; warping, equally so. To improve bed adhesion, you can try increasing the flow in 5% increments. By increasing the amount of plastic extruded, the first layer should have a greater surface area with which to adhere to the print surface.
However, don’t get rid of one print issue at the cost of causing another. Increasing the filament flow too much can result in over-extrusion and nozzle clogging.
If inadequate adhesion continues in your prints, read about our easy fixes for warping.