The characteristic of co extrusion is that two materials flow along their own independent channels, converge near the outlet of the die, and jointly extrude the die. When various melts with different rheological properties are co extruded through a common channel, multi-layer flow will be formed. How to ensure consistent pressure loss of materials in the common channel is considered a core issue in the design of co extrusion molds by plastic mold manufacturers. The connection between the main flow channel and the co extrusion flow channel is a difficult point in processing. In the process, it is necessary to ensure the accuracy of the flow channel and also consider the possible overflow problem caused by the different pressures of the main machine head and the co extrusion machine head during the extrusion process.

What are the requirements for co extrusion mold design?

In addition, for co extruded products with different functions, the plastic mold processing requires that the co extruded layer achieve completely different technical indicators on the profile, so different requirements are also put forward for the co extruded head design:

① When co extruding soft and hard materials, it is required that the co extrusion layer has a strong bonding force with the main profile. Therefore, when designing the co extrusion head, it is necessary to ensure that the two materials have sufficient bonding time inside the head.

② When co extruding new and old materials, due to the large proportion of co extruded materials, the design of the co extrusion head should mainly consider the balance between the old material flow channel and the mainstream material flow channel.

③ When using dual color co extrusion, it is generally required that the color co extrusion layer be thin and uniform. Therefore, in the design and manufacturing of the machine head, the joint between the co extrusion flow channel and the main flow channel is crucial to ensure sufficient precision.