Enter the melt temperature, mold temperature, ejection temperature, part thickness, and thermal diffusivity into the calculator to determine the injection molding cooling time.

Injection Molding Cooling Time Formula

The following formula is used to calculate the Injection Molding Cooling Time.

t = (h^2/(2*pi*a)) * ln [ 4/pi * (Tm – Tmo) / (Teject – Tmo) ]

  • Where t is the cooling time
  • h is the part thickness
  • a is the thermal diffusivity
  • Tm is the melt temperature
  • Tmo is the mold temperature
  • Teject is the ejection temperature

What is an injection molding cooling time?


An injection molding cooling time is the total amount of time it takes a material in an injection molder to cool to a point where it can be removed from the molder without distortion.

Typically, 80% of the time of an injection molder is spent cooling the product.

How to calculate injection molding cooling time?

Example Problem:

The following example outlines how to calculate an injection molding cooling time.

First, determine the part thickness. In this example, the part thickness is 25 mm.

Next, determine the thermal diffusivity. This is calculated to be 1.25.

Next, determine the melt temperature of the material. This material has a melt temperature of 400 F.

Next, determine the mold temperature. This is measured to be 300F.

Next, determine the eject temperature. This is calculated to be 350F.

Finally, calculate the cooling time using the formula above:

t = (h^2/(2*pi*a)) * ln [ 4/pi * (Tm – Tmo) / (Teject – Tmo) ]

t = (25^2/(2*3.14159*1.25)) * ln [ 4/3.14159 * (400- 300) / (350 – 300) ]

t = 74.38 s