In case of rubber extrusion dies there
is a great challenge for the extruders. The dies are to be designed in a
manner to get the material to flow naturally through the thick sections and
at a considerable distance from the thin edges. Then there is the problem of
the flow pattern within the die leading to flows that are too unbalanced for
an efficient extrusion process of the desired product. Another problem is
that of swelling of the rubber after it exits the die, which is also not
acceptable. Two types of rubber extrusion dies are popular and they are
preform and final die. Another popular die is the coin or plate die used in
the extrusion process of silicone rubber. The following image is of a rubber
extrusion die.

Let's see the position of extrusion dies in an extrusion line for producing
extruded rubber products.
Die design of Rubber Extrusion Dies
- The first and foremost consideration of a good extrusion die design
is the avoidance of dead spots. Actually these dead spots tend to catch
and hold the rubber as soon as it approaches the die. If a quantity of
rubber to be extruded gets trapped in the extruder for a considerable
period, there is every chance that due to frictional heat the rubber may
get vulcanized, leading to all sorts of troubles.
- There should be uniform flow of rubber through all the parts of the
die.
- Die designs should be flexible enough to allow for corrections or
adjustments.