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--- en:grafische_darstellung_der_ergebnisse:verweilzeit [2024/10/28 20:37] – neelest
+++ en:grafische_darstellung_der_ergebnisse:verweilzeit [2026/09/17 09:26] (aktuell) – gelöscht - Externe Bearbeitung (Unbekanntes Datum) 127.0.0.1
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-======Residence time ======
-The graphical representation of the calculated residence times in the screw extruder is an important tool for analysing and optimising the material flow during the plasticising process. This graph shows the average and minimum residence time of the material along the screw length and provides an insight into the thermal and mechanical behaviour of the plastic during its processing in the extruder. Dwell times are crucial for the quality of the end product, as they have a direct influence on the homogeneity, thermal stress and melt quality of the material.
-===== Process description=====
-  *    **Minimum dwell time (blue curve)**: The blue curve represents the minimum residence time of the material along the screw. It describes the shortest time that a material particle spends in the extruder. This dwell time is particularly important to ensure that even the fastest material flows are sufficiently thermally processed and exit the extruder homogeneously.
-  *    **Average residence time (red curve)**: The red curve shows the average residence time of the material. It describes the average time that a particle spends in the extruder before it leaves the extrusion process. The average residence time provides a general overview of the processing time and is an important indicator of the thermal load on the material.
-{{ :grafische_darstellung_der_ergebnisse:rex171_grafisch_en_007.png?nolink |}}
-===== Axis representation=====
-  *     **X-axis**: The length of the screw is plotted on the X-axis. This shows the position along the length of the screw, starting from the feed zone to the discharge zone of the extruder. This axis shows how the dwell time of the material changes along the various screw zones.
-  *     **Y-axis**: The Y-axis shows the dwell time in seconds. This indicates how long the material remains in the different areas of the screw before it is transported further or discharged.
-{{ :grafische_darstellung_der_ergebnisse:rex171_grafisch_en_015.png?nolink |}}
-=====Behaviour of the residence time curves=====
-  *     **Correspondence of the curves up to the point of melt vortex formation**: Up to the point of melt vortex formation, where the material begins the melting process, the blue and red curves overlap. This means that the minimum residence time in this area of the screw is identical to the average residence time. As the material is still in a solid state in the early zones of the extruder and is transported relatively homogeneously, there are no significant deviations in the residence time here.
-  *     **Deviation after the start of the melting process**: After the melt vortex formation, the two curves separate. In this area, the material begins to melt and there is a greater differentiation in the residence times. While some particles are transported faster through the screw (minimum residence time), others remain longer in the screw flights, especially in areas with higher shear or material compaction (average residence time). The difference between these curves is an indicator of the flow heterogeneity of the material.
-  *     **Vertical jumps due to downtimes and injection times**: Vertical jumps caused by downtimes and injection times can occur in the graphical representation. These jumps reflect interruptions in the continuous material flow, such as those that occur during the return of the screw or when the material is injected into the mould (in injection moulding processes). In these phases, the material stops for a certain period of time or is not transported any further, which leads to sudden increases in dwell times.
-=====Meaning of the dwell time curves=====
-  *     **Minimum residence time (blue curve)**: The minimum residence time gives an indication of whether the material that flows fastest through the extruder has been sufficiently thermally treated. If the minimum residence time is too short, there is a risk that not all material particles will be given the necessary time for homogenisation and complete melting.
-  *     **Average residence time (red curve)**: The average residence time provides a good overall overview of how long the material remains in the extruder on average. Too long a residence time can lead to thermal degradation of the material, while too short an average residence time can lead to incomplete melting and mixing.
-===Further topics===
-  * [[en:grafische_darstellung_der_ergebnisse:allgemeines_zum_reitersystem]]
-  * [[en:grafische_darstellung_der_ergebnisse:schnecke]]
-  * [[en:grafische_darstellung_der_ergebnisse:multigrafik]]
-  * [[en:grafische_darstellung_der_ergebnisse:druckverlauf]]
-  * [[en:grafische_darstellung_der_ergebnisse:aufschmelzverlauf]]
-  * [[en:grafische_darstellung_der_ergebnisse:temperaturverlauf]]
-  * [[en:grafische_darstellung_der_ergebnisse:leistung]]
-  * [[en:grafische_darstellung_der_ergebnisse:verweilzeit]]
-  * [[en:grafische_darstellung_der_ergebnisse:wandschubspannungen]]
-  * [[en:grafische_darstellung_der_ergebnisse:verweilzeitverteilung]]
-  * [[en:grafische_darstellung_der_ergebnisse:mischverhalten]]
-  * [[en:grafische_darstellung_der_ergebnisse:materialabbau]]
-  * [[en:grafische_darstellung_der_ergebnisse:scherdeformationsgradient_und_schergeschwindigkeit]]
-  * [[en:grafische_darstellung_der_ergebnisse:schlepp-druckstroemung]]
-  * [[en:grafische_darstellung_der_ergebnisse:kurzbericht]]
-  * [[en:grafische_darstellung_der_ergebnisse:langbericht]]