💉Injection Molding Parameters
Estimate rubber injection-molding process parameters — cavity fill time, gate size and the injection / hold pressures and clamp force.
✓ Result
Fill time
t_fill = V / Q
t_fill = V / Q
V = cavity + runner volume (cm³), Q = average flow rate (cm³/s), result in seconds.
🚪Gate Size (shear-rate based)
Size the gate so the compound's shear rate stays inside a safe window to avoid scorch and tearing at the gate.
✓ Result
Recommended gate
Effective shear rate
Gate sizing formulas
γ̇ = 4·Q / (π·r³) → d = 2·(4·Q / (π·γ̇))^⅓
Round gate: solve for diameter at the target shear rate. Rectangular slit: pick a depth ≈ 0.3–0.8 × wall thickness, then solve for width.
🔥Injection & Hold Pressure
Estimate the required machine injection pressure and the resulting clamp force from the average cavity pressure and projected area.
✓ Result
Estimated injection pressure
Recommended hold pressure
Required clamp force
The loss factor covers the nozzle, sprue, runners and gate (usually 1.5–2.5). Hold pressure is typically 50–90% of the injection pressure.