Skip to main content
Calcimator

Injection Molding Cooling Time Calculator

Calculate cooling time using the flat-plate analytical solution: t = (s²/(π²·α)) × ln(8(Tm−Tw)/(π²(Te−Tw))). Determines total cycle time and production rate.

Inputs

Results

Cooling time (s)

9.75

Total cycle time (s)

17.75

Parts per hour (1 cavity)202.9
Thermal diffusivity (mm²/s)0.11
Temperature ratio argument3.08
Fourier number at ejection0.11
Melt-mold temp diff (°C)190
How to Use This Calculator
  1. Enter Max wall thickness (mm), Melt temperature, Tm (°C), and Mold temperature, Tw (°C).
  2. Set Ejection temperature, Te (°C), Thermal conductivity k (W/m·K), and Density (kg/m³).
  3. Adjust Specific heat Cp (J/kg·K), Injection + packing time (s) as needed.
  4. Review Cooling time (s) and Total cycle time (s).
  5. Use Parts per hour (1 cavity) and Thermal diffusivity (mm²/s) to inform your decision.

How the result changes with Max wall thickness (mm)

Max wall thickness (mm)Cooling time (s)Total cycle time (s)
10108.29116.29
351,326.51,334.5
654,575.064,583.06
908,771.118,779.11

What each input means

Max wall thickness (mm)
Maximum wall thickness of the part. Cooling time scales with thickness squared.
Melt temperature, Tm (°C)
Polymer melt temperature at injection. PP ~230, ABS ~240, PC ~300°C.
Mold temperature, Tw (°C)
Mold wall (coolant) temperature. PP ~30-50, PC ~80-120°C.
Ejection temperature, Te (°C)
Temperature at which the part is rigid enough to eject without warping.
Thermal conductivity k (W/m·K)
PE ~0.33, PP ~0.12, ABS ~0.17, PC ~0.20, Nylon ~0.25 W/m·K.
Density (kg/m³)
Solid-state density. HDPE ~950, PP ~905, ABS ~1050, PC ~1200 kg/m³.
Specific heat Cp (J/kg·K)
PE ~2300, PP ~1900, ABS ~1400, PC ~1200 J/kg·K.
Injection + packing time (s)
Time for injection fill and packing phases.
Mold open/close time (s)
Time for mold open, ejection, and mold close.

What each result means

Cooling time (s)
Calculated cooling time from the analytical flat-plate solution.
Total cycle time (s)
Injection + cooling + mold open/close.
Parts per hour (1 cavity)
Theoretical production rate for a single-cavity mold.
Thermal diffusivity (mm²/s)
alpha = k / (rho * Cp). Determines heat transfer rate.
Temperature ratio argument
The 8(Tm-Tw)/(pi^2(Te-Tw)) term inside the logarithm.
Fourier number at ejection
Dimensionless time indicating degree of cooling completion.
Melt-mold temp diff (°C)
Temperature difference driving the cooling process.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Max wall thickness (mm) = 3, Melt temperature, Tm (°C) = 230, Mold temperature, Tw (°C) = 40, Ejection temperature, Te (°C) = 90 = 9 input(s) provided
  2. Calculate Cooling time
    Cooling time
    9.75 = 9.75
  3. Calculate Total cycle time
    Total cycle time = injectionTime + coolingTime + moldOpenClose
    17.75 = 17.75
  4. Calculate Parts per hour
    202.9 = 202.9
  5. Calculate Thermal diffusivity
    Thermal diffusivity = alpha * 1e6
    0.1053 = 0.1053

Related Calculators

The questions that sit next to this one — chosen by subject, including calculators filed under a different category.

Injection Molding

Cooling Time Calculator

Estimate part cooling time from wall thickness, melt temperature, mold temperature, and material thermal properties.

Injection Molding

Cycle Time Calculator

Calculate total injection molding cycle time from fill, pack/hold, cooling, and mold open/close phases.

Plastics

Injection Molding Clamp Tonnage Calculator

Calculate required clamping force for injection molding from projected part area, cavity pressure, number of cavities, and runner system.

Plastics

Shrinkage Compensation Calculator

Calculate mold cavity dimensions to compensate for plastic shrinkage in flow, cross-flow, and thickness directions. Assesses warpage risk and tolerance feasibility.

Food Safety

Cooling Time Calculator

Calculate cooling compliance for FDA 2-stage cooling requirements (135°F to 41°F).

More in Manufacturing, Industrial & Coatings.