Filling Pressure Calculator
Estimate the pressure required to fill the injection mold. The calculator accounts for flow path length, wall thickness, melt viscosity, and temperatures — key parameters for machine selection and injection feasibility verification.
Input Parameters
Results
Fill in the data and click Calculate
ARGUS automatically calculates filling pressure and verifies machine capabilities
Filling pressure determines machine selection and part quality — ARGUS combines this analysis with machine parameters and production history.
How do we calculate filling pressure?
Filling pressure is the pressure required to push the polymer melt through the runner system and mold cavity. It consists of the pressure drop in the runner, the pressure drop at the gate, and the pressure drop in the cavity. This is a key parameter for machine selection — the machine must provide sufficient hydraulic pressure.
The calculator uses a simplified pressure drop model based on the Hagen-Poiseuille equation for polymer melt flow through a rectangular cross-section channel (cavity wall). The model accounts for temperature-dependent viscosity.
ΔP — pressure drop [bar]
L — flow path length [mm]
s — wall thickness [mm]
η — melt viscosity [Pa·s]
Tm — melt temperature [°C]
Tw — mold temperature [°C]
Filling pressure increases proportionally with flow path length and viscosity, and decreases with the square of wall thickness. Therefore, thin-walled parts (<1.5 mm) require significantly higher pressure than thick-walled parts. Typical filling pressures: 500–1200 bar for standard parts, 1500–2000 bar for thin-walled parts.
Pressure and machine selection
Filling pressure is one of the key parameters for machine selection. Typical injection molding machines offer maximum injection pressure of 1400–2500 bar. A pressure margin of at least 20% above the calculated filling pressure should be maintained.
Thin-walled (<1.5 mm) — 1200–2000 bar
Engineering (PC, PEI) — 800–1800 bar
Packaging (PP, PS) — 400–1000 bar
Melt viscosity depends on temperature and shear rate. Higher temperature reduces viscosity, which lowers the required pressure, but increases the risk of thermal degradation. Optimal melt temperature is a compromise between low filling pressure and acceptable cooling time and surface quality.
When to apply with caution
The simplified model gives a good approximation for parts with uniform wall thickness and simple geometry. For parts with variable thickness, ribbing, or complex 3D geometry, the actual pressure can be 20–50% higher than calculated. In such cases, flow simulation is essential.
ARGUS automatically verifies filling pressure against the capabilities of available machines
See it for yourself — book a presentation and discover how ARGUS combines pressure analysis with machine selection.