Injection molding ยท Mold geometry
Runner Volume Calculator
Cold-runner volume from circular runner diameter and total centerline length. Use this as a documented planning estimate, then validate it against the actual machine, mold, resin, and process.
Formula and method
Volume = pi x diameter squared / 4 x length.
Use CAD runner centerlines and the actual circular section; runner geometry affects material use and pressure loss.
Inputs and units
Use controlled records, CAD, measured production data, the exact resin data sheet, or machine-maker specifications. Keep the material and time basis with the result.
Worked example
A 6 mm runner over 800 mm has 22.62 cm3 volume.
What the result supports
This result is a first-pass screen for mold geometry planning. Use it to identify the next record or engineering check, not as a release decision.
Sanity check
Check the unit basis and whether all quantities describe the same cavity, shot, machine, or production window before comparing values.
Important limitation
Runner shape, taper, gates, and hot-runner manifolds need their own geometry.
Reference: Autodesk: runner layout.
Next calculation
FAQ
What must be checked after using runner volume calculator?
Retain the input source and compare this estimate with the applicable machine, mold, supplier, or production record before relying on it.