Injection Molding
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Large injection pressure fluctuation in random copolymer polypropylene '2079851475616104452
Problembeschreibung
The pressure gauge reading fluctuates greatly during injection, with pressure differences exceeding ±5% within the same cycle or between different cycles.
Pressure fluctuation causes instability in product weight, dimensions and quality, and in severe cases short shots or flash appear alternately.
Ursachenanalyse
(1) Hydraulic system pressure is unstable, with hydraulic pump wear or hydraulic oil contamination
(2) The screw check ring is worn, making each shot volume inconsistent
(3) Barrel temperature fluctuates greatly; melt viscosity changes cause pressure fluctuation
(4) Feeding is uneven, making each plasticizing volume inconsistent
(5) Screw speed is unstable, and plasticizing quality fluctuates
Lösung
(1) Check the hydraulic system, repair or replace the worn hydraulic pump, and replace the hydraulic oil
(2) Check the check ring; replace if wear exceeds 0.1mm
(3) Stabilize barrel temperature, with fluctuation of each section controlled within ±3°C (190-260°C range)
(4) Check the feeding system to ensure smooth hopper feeding and stable material level
(5) Stabilize screw speed and back pressure to ensure plasticizing consistency
Wichtigste Erkenntnis
Injection pressure fluctuation is caused by hydraulic system instability or plasticizing inconsistency; the hydraulic, screw and temperature control systems need to be systematically investigated.
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