How many points should an Equipment Protection Case wall be measured at?

Answer: Five per unit, centre plus four corners, clear of ribs. A single reading can sit 0.6 mm above the thinnest point.

Where should the vacuum limit sit?

Answer: 0.25 kPa over sixty seconds at minus 3 kPa is common. Past 0.5 kPa the contact line is broken.

Can a strap rescue a weak latch?

Answer: Only as a concession. A strap covers release, not boss deformation.

Must a whole lot go back after one failure?

Answer: No. Track it to a cavity, shift or batch, then reject that scope.

60-Unit Equipment Protection Case Audit: Limits and Verdicts

Quick answer: An Equipment Protection Case is accepted on numbers, not looks. Thirteen samples from a sixty-unit lot pass six checks, and each result read against a limit fixed before opening.

Why thirteen samples from a sixty-unit lot
Appearance, marking and stack condition
Dimensions and wall thickness: three gauges
Seals, latches and the pressure valve on site
Foam fit, drop and stack tests
Verdicts and disposition: rework, concession, rejection
FAQ

1. Why thirteen samples from a sixty-unit lot

Sixty Equipment Protection Case units arrived to carry a portable spectrometer of 7.4 kg. Sampling followed GB/T 2828.1 level II: a lot of sixty gives code letter E, thirteen samples, AQL 1.0, zero acceptance and one rejection.

One bad unit in thirteen stops the lot.

Verdict lines were signed off before the first lid opened, allowing only pass, fail or retest.

Four units came from each of three pallet layers, with cavity numbers covering all four moulds.

2. Appearance, marking and stack condition

Inspection began at the loading bay, in good light. The delivery stood five high, and a bulging bottom unit meant load was pressing the lid.

Equipment Protection Case: olive green rotomoulded case on a rusted steel shelf, two latches and a recessed handle, scuffed shell, warehouse racking behind

Seven points, by eye and hand:

Flash: finning over 0.5 mm at the parting line
Colour: drift beyond 1.5 units in daylight
Flow marks: broad patches on the base
Plate: model, batch, cavity number
Latch boss: whitening cracks at the root
Gasket end: joint offset over 1 mm
Feet: four touching, rock under 1 mm

3. Dimensions and wall thickness: three gauges

Two people can measure one unit 2 mm apart, so gauge, point and limit were fixed in advance.

Item	Gauge	Points	Limit
Outline	Steel tape	Three directions	Within 3 mm
Cavity	Tape and square	Two directions	Within 1.5 mm
Wall	Ultrasonic	Five per unit	3.8 mm minimum
Wall range	Ultrasonic	Same five	0.4 mm or less
Tongue	Vernier	Four per unit	7.5 mm plus or minus 0.3 mm
Latch boss	Vernier	Two per unit	5.0 mm minimum

Wall thickness carried the only systematic bias in this Equipment Protection Case lot. Three units read 3.6 mm at the base centre against 4.4 mm at the corners, an 0.8 mm spread where 0.4 mm was allowed. Powder piles in corners and thins across flats, so nominal sits at 4.2 mm, keeping margin at the thinnest point.

Those three went on hold.

4. Seals, latches and the pressure valve on site

The seal was proved by vacuum, not water.

Four latches closed, a pump on the valve port, minus 3 kPa, then sixty seconds of watching against a 0.25 kPa ceiling. Two units lost 0.4 and 0.6 kPa, gasket pushed 2 mm out on the hinge side.

Latches were pulled sideways with a force gauge. The limit was 220 N, eight Equipment Protection Case units read 240 to 280 N, and the weakest at 205 N traced to a thin boss rather than the latch.

The valve had to balance 0.1 bar in ten seconds.

5. Foam fit, drop and stack tests

The insert ran three layers: egg-crate sheet, compartment trays, two flat sheets.

Equipment Protection Case: open olive green case on a steel bench, black lid foam cut with long slots, compartment trays of sealed packs, racking behind

Fit is read on remaining travel. A 3 mm cork shim, ten seconds of lid pressure, and the imprint decides: broken means no contact, see-through means densification. Four units showed split imprints from glue laid without full pressure.

The Equipment Protection Case drop used two units: one corner, three edges, six faces, 1.2 m onto concrete after four hours at minus 25 °C. No crack, no latch release, no shift past 3 mm.

Stack ran five high at 60 kg, replaced by a 400 kg plate for twenty-four hours, capped at 3 mm.

6. Verdicts and disposition: rework, concession, rejection

Ten passed, three failed: wall at 3.6 mm, latch at 205 N, gasket offset of 2 mm, all from one cavity.

Failure	Risk	Disposition	Recheck
Thin wall	Weak drop margin	Reject cavity, supply 8	Five-point gauge
Latch at 205 N	May pop in a drop	Concession plus strap	Pull every unit
Gasket offset	Vacuum loss	Re-seat, then retest	60 seconds at minus 3 kPa
Collapsed foam	Load shifts	Rework, press 10 seconds	Continuous imprint

Wall and latch touch safety margin and get no concession. Foam glue and print position rework and recheck. Anything between is accepted with written conditions.

Rejecting an Equipment Protection Case lot over one unit is hard, since a pallet goes back and the schedule moves. Here all three went back, but only across the fifteen units from that cavity.

Conclusion

An audit closes on one sheet when gauges are assigned, limits are written and rejection scope follows the evidence. Thirteen units out of sixty pointed at one cavity. Numbers on the sheet decide it, and an Equipment Protection Case stops resting on opinion.

This article discusses only the container (case body) side of specifications and design intent, and does not cover any handling, loading or use of the contents.