Hello and welcome to a new blog post. In a previous post, I presented the residence time calculation in injection moulding. Today we will focus on the extrusion process.
Residence time in extrusion is referring to the time, which a polymer
pellet, and as consequence, polymer melt needs to travel from the melting zone
until the end of the metering zone.
The online calculation
For an approximate calculation of the residence time, building the quotient
of the volume of the extruder filled with melt and the volume flow of the melt
is possible (underlying basic laws of physics). This is the background of the
online calculation tool shown below:
In literature, extruder output can be calculated by the following equation
[3]:
The leakage flow is calculated by addition of mass flow rate (drag) and
pressure flow rate minus the extruder output.
Also as a general rule, the higher the temperature, the lower should be the
melt residence time.
Thanks for reading and #findoutaboutplastics
Greetings
Herwig Juster
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Literature:
[1] https://www.findoutaboutplastics.com/2017/10/how-to-calculate-residence-time-in.html
[2] https://www.extrusion-training.de/extruder-dimensionierung/
[3] N. Rao: Design formulas for plastics
engineers
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