Pressure loss in injection mold runner

In injection mold molding, the molten plastic material flows in the flow channel and reaches the cavity after passing through the gate. During this series of flows, pressure is gradually lost. CAE can be used to judge the predicted trend of pressure drop, but in order to optimize the necessary precise flow state in the actual injection molding, it is very important to think about the theory-based thinking and then apply the experience gained through fine-tuning trial and error.

1. Location of flow path expansion or contraction

Where the cross section of the flow path expands or contracts, vortices are created, resulting in a loss of pressure. In particular, the sudden expansion and contraction of the flow path will cause great pressure loss, so it must be strictly avoided.

2. The position where buckling or bending occurs

Eddy currents can be created in the buckling or bending part, resulting in a loss of pressure.

3. Bend the flow path

In the part of the flow path bent at a certain Angle, the flow will first contract and then expand, resulting in a loss of pressure.

4. Near the entrance of the flow road

Eddy currents can be created near the inlet where the fluid flows in, resulting in loss. The pressure loss may be reduced by the size of the inlet Angle site R.

Injection mold molten plastic is a fluid with a certain viscosity, belonging to the viscous fluid. And plastic has a unique characteristic, that is, the viscosity will change with the temperature of the plastic, when the temperature of the resin below a certain range, it can not flow, but begins to cure.