Mold Cooling Circuit Components

Parallel Circuits: Uniform Heat Extraction

In parallel cooling, the main supply is branched so that each channel receives fresh coolant directly at the same inlet temperature ($T_{in}$).
Thermal Performance: Maintains strict cavity temperature uniformity, keeping mold temperature gradients ($\Delta T_{mold}$) under $2^\circ\text{C}$. This is critical for preventing asymmetric shrinkage and subsequent part warpage.
Fluid Dynamics: The system total pressure drop equals that of the single branch with the highest flow resistance ($\Delta P_{total} = \Delta P_{branch}$). However, the total volumetric flow rate is the sum of all individual channels ($Q_{total} = \sum Q_i$). Flow balance valves must be used to prevent coolant from short-circuiting through paths of least resistance, which would leave narrower channels in a laminar regime ($Re < 2,300$).

Series Circuits: Simple Plumbing with Cumulative Heating

In series cooling, the coolant flows through all channels sequentially.
Thermal Performance: The coolant absorbs heat continuously, causing its temperature to rise linearly: $$\Delta T_{fluid} = \frac{q}{\dot{m} \cdot C_p}$$ Where $q$ is heat transfer rate, $\dot{m}$ is mass flow rate, and $C_p$ is specific heat capacity. This cumulative heating typically causes downstream cavities to run $3^\circ\text{C}$ to $8^\circ\text{C}$ hotter, leading to cavity-to-cavity shrinkage variation.
Fluid Dynamics: Plumbing is simple (one hose in, one hose out) and the total flow rate equals a single channel ($Q_{total} = Q_{channel}$). However, the total system pressure drop accumulates with every channel: $$\Delta P_{total} = \sum \Delta P_{channel} + \sum \Delta P_{bends}$$ According to the Darcy-Weisbach equation, this high pressure drop can easily exceed the capacity of standard mold chillers, leading to a drastic drop in flow rate and a collapse of heat transfer coefficients.