Blow Moulded Bottle Weight Trimmed until the Drop Test Fails
Trimming blow moulded bottle weight reduces unit resin costs but narrows drop test safety margins along bottom pinch seams and heel radii.
Hall Effect Gauge
Meaning
Precision non-destructive inspection instruments measure the thickness of non-magnetic materials by detecting magnetic field strength variations across a target. Operation of a hall effect gauge positions a magnetic probe against the outer surface of a plastic container while a ferromagnetic target ball rests against the corresponding inner wall. The technique provides accurate thickness measurements for blow moulded bottles, thermoformed trays and composite structures without requiring destructive sectioning, stopping where ferromagnetic materials or inaccessible interior cavities prevent target ball placement.
Measurement Physics
A sensor positioned inside the external probe produces an electrical voltage proportional to the perpendicular magnetic field strength generated by a permanent magnet. Placing a small steel target ball inside the plastic container creates a localized magnetic circuit through the non-magnetic plastic wall. As material thickness increases, the physical distance between the probe tip and the target ball widens, attenuating the detected magnetic flux density.
The internal microprocessor converts this voltage change into a direct thickness readout with precision down to one thousandth of a millimetre.
Plant Metrology
Quality inspectors scan the probe across complex container geometry to map wall thickness profiles in real time. The target ball tracks the probe movement continuously along the exterior surface, rolling smoothly across tight internal radii, recessed base chimes and handle pinch zones. Unlike manual mechanical calipers that require cutting the container apart, a hall effect gauge preserves the specimen for subsequent top-load, drop impact or environmental stress cracking evaluation.
Operators detect thin spots caused by improper parison programming or mold temperature imbalances without damaging finished goods inventory.
Tooling Verification
Tooling qualification and new mould commissioning utilize non-destructive thickness mapping to validate cavity balance. Multi-cavity extrusion blow moulding operations exhibit subtle wall thickness variations between cavities due to manifold flow imbalances or cooling circuit differences. Measuring containers with a hall effect gauge verifies that parison profile settings deliver required minimum wall thresholds across all active mould cavities.
Calibration routines employ certified plastic shims to maintain gauge accuracy across shifting ambient shop-floor temperatures. Metrology records provide defensible wall distribution data for quality audits and customer specification compliance.