For the uniformity of the thickness of the coating of t […]
For the uniformity of the thickness of the coating of the cable extrusion molding die, the size of the runner on the mandrel is extremely important. The following conditions must be met.
1. The melt in the die along the annular gap should have a constant flow rate and the same pressure drop.
2. The melt has a constant shear rate at various points along the flow path.
3. The residence time of the melt along each point of the flow channel is approximately the same.
The flow channel distribution system on the mandrel shaft is designed in a variety of ways, including a threaded core flow channel and a heart-shaped curve flow path. The most used is the heart-shaped curved flow path. The melt is divided into two streams, each of which surrounds about half of the core until the two melts rejoin. The two processes should be equal.