What AQL suits a military box acceptance standard?

Answer: 1.0 for major defects, 2.5 for minor, and no sampling for critical ones, which reject the lot on sight. At 501 to 1200 pieces, 80 samples give Ac 2 and Re 3.

Must illuminance and viewing distance be fixed?

Answer: Yes. D65 light, 800 to 1000 lx, 500 mm and 10 seconds per piece; without them one case passes in two rooms with two verdicts.

How long is a sealed sample kept?

Answer: Six months after delivery, with records held for 3 years. The sample is the physical reference for colour and feel disputes.

Can one customer sample serve as the basis?

Answer: Only as a reference. Convert it into drawing tolerances plus a defect scale, then seal it.

Military Box Acceptance Standards: Inspection and Judgement

Q: How are destructive tests sampled?

Answer: They are not counted. Drop, salt spray and pressure decay take 3 pieces per lot, and one failure rejects the lot.

Quick answer: A workable standard is not a checklist. It is a defect scale, a sampling plan and a failure criterion working together: grade defects by function, fix the sample size and accept number, then give every test a visible failure point.

Grade Defects Before Measuring
Sampling Plans and Accept Numbers
Visual and Dimensional Checks
Functional and Environmental Limits
First Articles, Samples and Records
FAQ

1. Grade Defects Before Measuring

Grading comes before measuring. The same scratch shortens life on a load-bearing face and merely offends the eye on the underside, so an ungraded military box standard turns every verdict into a personal opinion.

Three classes cover most programmes. Critical defects break sealing, load capacity or latching, such as a pierced wall or a broken catch; major defects affect assembly or service life, such as sink marks deeper than 0.5 mm; minor defects stay cosmetic, such as flow marks under 4 mm². One critical piece rejects the lot and triggers traceability by mold number.

Class	Definition	Examples	Action
Critical	Breaks sealing, load or latching	Pierced wall, broken catch	One piece rejects the lot
Major	Affects assembly or life	Sink marks over 0.5 mm	Counted against AQL
Minor	Cosmetic only	Flow marks under 4 mm²	Capped by ratio

2. Sampling Plans and Accept Numbers

Sample size on a military box lot follows lot size. A lot of 501 to 1200 pieces at inspection level II gives code letter J and 80 samples; 1201 to 3200 moves to K and 125 samples. At AQL 1.0, Ac 2 and Re 3 decide the lot: two nonconforming pieces accept it, three reject it.

Major defects run at AQL 1.0 and minor at 2.5, judged separately and never pooled. Destructive tests on a military box sit outside counting sampling: drop, salt spray and pressure decay take 3 pieces per lot as type confirmation, and a single failure rejects the lot.

Lot size	Code	Sample	Ac / Re
281–500	H	50	1 / 2
501–1200	J	80	2 / 3
1201–3200	K	125	3 / 4

3. Visual and Dimensional Checks

Visual checks on a military box need fixed conditions: D65 light at 5000 to 6500 K, 800 to 1000 lx on the surface, a 500 mm distance, 10 seconds per piece and a 45 degree sight line. Left unwritten, the same case passes in the workshop and fails in the inspection room.

Critical military box dimensions, the 5 to 8 features tied to sealing, stacking and latching, are checked on every piece with calipers and plug gauges. General dimensions take 5 samples per lot on a CMM, plus 10 more on any deviation. Colour holds within ΔE 1.5 at three points, and marking text at 6 mm survives three tape pulls.

4. Functional and Environmental Limits

A military box latch must still close one-handed after 5000 cycles, with no hinge play. Sealing is measured by pressure decay: charge to 20 kPa, hold 60 seconds, and allow no more than 0.3 kPa of loss. Both values go into the record, not a tick box.

Conditions follow the actual logistics chain. Drop from 1.2 m onto six faces, three edges and one corner with the case ballasted; 30 minutes of rain under an oscillating tube; 96 hours of salt spray; 4 hours at minus 40 °C and at plus 60 °C. After a drop, check latches, gasket and foam, not just shell cracks.

Item	Condition	Failure criterion
Latch life	5000 cycles	Cannot close one-handed, hinge play
Pressure decay	20 kPa held 60 s	Loss above 0.3 kPa
Drop	1.2 m, six faces, three edges, one corner	Cracks, open latch, shifted gasket

5. First Articles, Samples and Records

A military box batch starts with a first article: once mold, material and parameters settle, 3 pieces are inspected in full and 1 is sealed, kept 6 months after delivery. Lot, mold, material batch, inspector and date form five aligned columns held for 3 years, with rework, concession or scrap written against every nonconforming piece.

Change control on a military box belongs here too. A new material grade, mold or supplier needs a fresh first article plus drop and pressure-decay confirmation, otherwise the old record does not cover the new batch.

Conclusion

Reliability comes from three pieces: a defect scale that turns opinion into classes, a sampling plan that fixes sample size and accept number, and failure criteria an inspector can see. Fixed in a document, a military box acceptance standard becomes reproducible.

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.