MANUFACTURING – INJECTION MOULDING & PLATIC CALCULATOR
Cooling Time Injection
A precise tool.
What is the Cooling Time Injection & How does it work?
In injection moulding the part solidifies by extracting heat through the mould cavity walls. The rate at which heat is removed depends on the materialβs thermal conductivity, density and specific heat, as well as the partβs thickness and the temperature gradient between the melt and the mould. A common engineering approximation for the cooling time (t_c) of a flatβplate part assumes oneβdimensional heat flow and uses the materialβs thermal diffusivity (Ξ± = k/(Οc)). The larger the thickness, the longer the heat must travel, and the cooling time grows with the square of the thickness. The resulting expression can be written as a closedβform solution that also accounts for the desired final core temperature. This allows designers to quickly estimate cycle times and optimise mould temperature or material selection.
t_c = frac{rho c t^{2}}{k pi^{2}} lnleft(frac{T_{text{melt}} – T_{text{mold}}}{T_{text{melt}} – T_{text{core}}}right)
t_c = cooling time (s)
rho = material density (kg/mΒ³)
c = specific heat (J/(kgΒ·K))
t = part thickness (m)
k = thermal conductivity (W/(mΒ·K))
T_{text{melt}} = melt temperature (Β°C)
T_{text{mold}} = mould temperature (Β°C)
T_{text{core}} = target core temperature (Β°C)
rho = material density (kg/mΒ³)
c = specific heat (J/(kgΒ·K))
t = part thickness (m)
k = thermal conductivity (W/(mΒ·K))
T_{text{melt}} = melt temperature (Β°C)
T_{text{mold}} = mould temperature (Β°C)
T_{text{core}} = target core temperature (Β°C)
Parameters
Result
β
Frequently Asked Questions
How does part thickness affect cooling time in injection moulding?
The thicker the part, the longer the cooling time required.
What is thermal diffusivity in the context of injection moulding?
Thermal diffusivity (Ξ±) is a material property that affects how quickly heat spreads through the part during cooling.
How do I calculate the cooling time for an injection moulded part?
Use the formula t_c = L^2 / Ξ±, where L is the thickness of the part and Ξ± is the thermal diffusivity.
What factors influence the rate of heat extraction in injection moulding?
Material properties like thermal conductivity, density, and specific heat, as well as part thickness and temperature gradient, influence heat extraction.
Why is one-dimensional heat flow assumed in this cooling time approximation?
One-dimensional heat flow simplifies the calculation by assuming heat transfer occurs primarily along one axis through the part.
Can I use this calculator for non-flat parts?
This calculator assumes a flat-plate part, so it may not be accurate for complex geometries or non-flat shapes.
What units should I use for the material's thermal diffusivity in this calculation?
Thermal diffusivity should be in units of mmΒ²/s for consistency with typical part dimensions in injection moulding.
Results are for informational purposes only and do not constitute professional advice.