Mold Cooling Reynolds Number Calculator

Calculate coolant velocity and Reynolds number for a mold cooling circuit. Use controlled coolant, machine and mold records; this calculator does not approve a process or equipment selection.

Formula and method

Re = ρ × v × Dh / μ. Flow regime is a screen; 4,000–8,000 is a SmartFlow mold-cooling reference range, not a universal pass/fail rule.

Inputs and units

Use stated SI units and verified fluid properties.

Worked example

8 mm diameter, 8 L/min water at 20°C gives about 21,135.95 Re.

What the result supports

Use this result to prepare the next circuit or equipment check.

Sanity check

Confirm the same circuit, fluid state and stable time window.

Important limitation

Do not use the estimate as a process release or equipment selection.

Next calculation

Continue through the documented cooling workflow.

FAQ

What must be measured after using this calculator?

Verify flow, temperature, property basis and circuit condition in the mold.

Inputs and validation

Obtain circuit diameter or validated hydraulic diameter, measured flow, supply/return temperature and coolant condition from the actual mold circuit. Water properties used by default approximate clean water near 20°C; for glycol mixtures or other temperatures, enter supplier-verified density, viscosity and specific heat rather than extrapolating.

Interpretation and limitations

Record pressure loss, manifold position, hoses, scale, fittings and sensor calibration. A high Reynolds number has diminishing cooling benefit and can increase pump energy. Confirm any result with stable-state flow and temperature measurements.

Related workflow

Cooling Time → Mold Heat Removal → Required Flow → Reynolds → Water Temperature Rise → Chiller Size.

Sources

SmartFlow cooling resources · Conair chiller sizing · Dow glycol guide.