Meaning
Continuous loss-in-weight dosing systems maintain solid material feed rates by measuring weight changes over precise time intervals using load cells and variable speed drives. Gravimetric feeder drift occurs when calibration errors or mechanical binding skew load cell readings away from actual mass discharge values over extended operating cycles. Continuous compounding and extrusion processes monitor this phenomenon to prevent raw material proportioning errors in composite manufacturing lines.
Uncorrected drift causes subtle stoichiometry deviations, resulting in out-of-specification material properties in final extruded products.
Sensor Creep
Thermal expansion and mechanical vibration induce progressive zero-point shifts in strain gauge sensors. Load cell creep generates false mass flow calculations, causing the control system to speed up or slow down feeder screws inappropriately. Scheduled recalibration cycles re-zero load cells under empty hopper conditions to prevent cumulative dosing errors.
Control Stability
Proportional integral control loops adjust motor speeds to match target mass loss rates over time. Excessive gain settings amplify signal noise from mechanical agitators, generating artificial fluctuations that accelerate gravimetric feeder drift. Tuning algorithm response damping filters out low-amplitude mechanical noise while maintaining precise mass delivery rates.
Process Risk
Unnoticed dosing deviations lead to off-spec polymer blends or improper additive ratios. Extrusions containing improper filler ratios fail tensile strength tests during batch audits, forcing expensive scrap reclaims or product recalls. Automated material tracking systems trigger safety alarms when dosing corrections exceed historical baseline thresholds.
