How max flow and print speed relate

Your hotend can only melt so much plastic per second — its max volumetric flow (mm³/s). Print faster than that and the extruder skips and under-extrudes.

The amount of plastic you lay down per second is speed × layer height × line width, so the fastest you can safely print is:

max speed (mm/s) = max flow ÷ (layer height × line width)

• Thicker layers and wider lines use more plastic per mm, so your max speed drops.
• Pressure advance (the PA value on each page) keeps corners sharp at speed — set it as a starting point and tune.
• Real max flow varies with hotend, nozzle, temperature and material — always run a flow-rate test.

Values from OrcaSlicer wiki defaults and manufacturer specs, linked per page. Outer walls usually print slower than this limit for quality.