Injection Molding
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Large Weight Fluctuation of Low-Density Polyethylene Injection Molded Products
Problem Phenomenon
The weight of products continuously produced with the same mold is unstable, with the fluctuation exceeding ±2%.
Weight fluctuation reflects process instability and directly affects the consistency of dimensional accuracy and mechanical properties, and is especially critical in precision '2079851475616104452.
Cause Analysis
（1）The screw check ring is worn or damaged, and the injection amount is inconsistent each time
（2）The plasticizing back pressure is unstable, and the melt density fluctuates
（3）The barrel temperature fluctuates greatly, and the melt density changes with temperature
（4）The injection speed is unstable, and the hydraulic system pressure fluctuates
（5）The raw material supply is discontinuous, with bridging at the discharge opening or unstable material level
Solution
（1）Check the screw check ring, replace it if the wear exceeds 0.1mm, and ensure consistent injection amount each time
（2）Stabilize the back pressure at 5-8MPa, with the back pressure fluctuation not exceeding ±0.5MPa
（3）Stabilize the barrel temperature, with the fluctuation of each section controlled within ±3°C (160-220°C range)
（4）Check the pressure stability of the hydraulic system, and repair the hydraulic pump and valves when necessary
（5）Ensure smooth discharge, install a magnetic rack on the hopper to prevent metal impurities, and avoid bridging
Key Takeaway
Weight fluctuation is caused by unstable plasticization and metering, and needs to be solved from the screw check ring, temperature control, and hydraulic system stability.
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