Injection Molding
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Large Weight Fluctuation of High-Density Polyethylene Injection-Molded Products
Problem Phenomenon
The weight of products continuously produced from the same mold is unstable, with fluctuations exceeding ±2%.
Weight fluctuation reflects process instability, directly affecting dimensional accuracy and mechanical property consistency, and is especially critical in precision '2079851475616104452.
Cause Analysis
(1) The screw non-return ring is worn or damaged, and the injection amount is inconsistent each time
(2) The plasticization 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 feed opening or unstable material level
Solution
(1) Check the screw non-return ring; replace it if the wear exceeds 0.1mm to ensure consistent injection amount each time
(2) Stabilize the back pressure at 5-8MPa, with back pressure fluctuation not exceeding ±0.5MPa
(3) Stabilize the barrel temperature, with the fluctuation of each section controlled within ±3°C (range 180-260°C)
(4) Check the pressure stability of the hydraulic system, and repair the hydraulic pump and valves if necessary
(5) Ensure smooth feeding; install a magnetic frame 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 non-return ring, temperature control, and hydraulic system stability.
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