Correction of a Flow Defect


Customer Request

Following the production of a tube with a new material, variations in thickness in the tube section were observed on the dies.

Our Analysis

The first observation is that these variations appear in the extension of the dies during extrusion.
The second observation is that the new material used is much more viscous than the materials usually processed on this production line.
This type of flow defect is often due to the design of the die. In these cases, the tube is produced on an extrusion line equipped with a four-outlet die. Other outlets support the main flow and the pin. It is then clear that the design of the outlets disrupts the flow of the new material.
To correct this thickness variation in the tube section, it is necessary to reconsider the flow path design of the material.

Our Solution

A new design of the outlets and the spiral will correct this defect. The client wishes to modify or manufacture a new block for prototyping only.
The most appropriate solution was to modify the design of the pin (a pin is available for production) to correct the flow defect as much as possible.

Original pin

Poinçon modifié pour corriger un défaut d'écoulement

Modified pin

The Result

For a line speed between 80 and 150% of the nominal speed, the thickness deviations in the tube section are no longer detectable with the available control means. Beyond the mentioned speeds, flow defects reappear.
The prototyping phase is now complete, leading to validation by the requester. If production is decided, a new design of the outlets and block will be proposed and manufactured.