Adapter flow
Vol. 22 #2, Sept. 1995
It is important to remember that the flow through the center of an adapter is generally at a higher temperature than at the wall. Plastic is typically a poor conductor of temperature so cooling at the wall will not significantly affect the center of the melt stream. Consequently, the adapter temperature(s) should be set at, or even slightly above, the actual melt temperature.
If an adapter zone is set below the actual melt temperature, it can induce or exacerbate a temperature gradient. Temperature gradients often lead to undesired flow variations and/or create gauge problems.
See also
Adapter flange leak
Restrictive adapter