I. Give fixing the underlying cause of drift top priority.
Stop production right away and verify the drift channel's true deviation by using a reference calibrator to examine the hot runner signal generator's output divergence.
Recalibrate the drifting signal generator so that the temperature control system's reference error is eliminated and the full-range output accuracy deviation is controlled within ±0.05%FS.
Verify each hot runner temperature control channel's displayed and real temperatures after calibration, and adjust any temperature variations to guarantee a consistent melt temperature in every cavity.
II. Improve Injection Moulding Process Settings
Modify Back Pressure: To remove gas from the barrel, enhance the stability of the melt density, and prevent variations in the melt weight during the same metering stroke, appropriately raise the back pressure of the molten material.
Optimise Holding Pressure Parameters: To counteract the filling volume changes brought on by uneven melt temperature, extend the holding time and suitably raise the holding pressure to guarantee adequate melt shrinkage before the gate freezes.
Stabilise the Plasticising Process: Stabilise the injection volume per mould from the source and modify the plasticising duration to guarantee adequate melt melting in each mould, preventing melt density variations brought on by uneven plasticising.
Verify Buffer Amount: During the holding pressure stage, make sure there is enough buffer to transmit melt pressure. This will stop inadequate holding pressure from acting on the cavity and causing weight fluctuations.
III. Hardware Diagnostics and Supplementary Modifications
Examine the check ring on the injection moulding machine for wear. To avoid erratic variations in injection volume per mould, replace the part as soon as melt backflow is noticed.
To guarantee steady and continuous discharge and prevent barrel voids that lead to variations in feed weight, clear the hopper discharge channel.
To ensure uniform filling speed in every cavity and minimise weight disparities in multi-cavity items, appropriately enlarge the tiny gate in the hot runner.
To prevent variations in product weight brought on by variations in cooling shrinkage, adjust the mould temperature to guarantee consistent cooling of every cavity.
Once the adjustments are finished, run 30 consecutive mould cycles, weighing each piece for verification, until the product weight CPK satisfies the process capability requirements. Only then can stable production be restarted.
