Injection Molding worked example

Cooling Water Flow with heat load to remove from mold of 6 kW: a worked example

Here is what the math looks like when conditions slip. We hold every other input steady and drop heat load to remove from mold to 6 kW, then walk the calculation through step by step. Calculate required cooling water flow rate from heat load, allowable temperature rise, and a safety margin for scaling or restrictions.

The inputs for this scenario

  • Heat load to remove from mold: 6 kW (the input this scenario stresses; the baseline uses 12)
  • Allowable water temperature rise: 3 °C (held at the documented default)
  • Safety factor for fouling/restrictions: 1.2 x (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Base flow = Heat load / (Water specific heat x Temperature rise).
  • Result works out to 21.6 L/min at these inputs, and this is the headline figure for the scenario.
  • Minimum flow (without safety factor) works out to 21.6 value at these inputs.
  • Multiplier works out to 1 x at these inputs.
  • Factor A x B works out to 18 value at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where heat load to remove from mold sits at 12 kW and the headline result is 43.2 L/min, this scenario comes in 50% below the baseline at 21.6 L/min.
  • The practical read: the gap between this scenario and the baseline is entirely attributable to heat load to remove from mold, so recovering it is worth quantifying in dollars before considering equipment or staffing changes. It sizes total flow but does not guarantee turbulent flow in each individual channel; flow must still be distributed so every circuit reaches a Reynolds number above about 4,000.

Results at a glance

  • Result: 21.6 L/min (headline result)
  • Minimum flow (without safety factor): 21.6 value
  • Multiplier: 1 x
  • Factor A x B: 18 value

Run it with your numbers

  • To rerun this with your own numbers, open the live Cooling Water Flow calculator, set heat load to remove from mold to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.