Why measure the lid gap of a Fuze Pack Assembly in three places?

Answer: Centre front proves seating, the corners show whether shrink is symmetrical, and 0.3 mm of spread settles it without a survey.

How many drops are enough?

Answer: Nine, on one case. Swapping midway destroys comparability, since every impact rearranges stress in the corners.

Are more latches always safer?

Answer: No. Two up to a metre, four beyond 1.2 m; crowd them and the land arches between latches, where the gasket loses contact.

Should a cold drop test come before signing?

Answer: After the ambient drops pass. Ambient proves the structure, cold proves the material.

A Sampling Rework: Judging Fuze Pack Assembly Fit

Quick answer: Most sampling reworks trace back to three interfaces, not a weak shell: lid to rim, insert to part, latch to rim. One rework, six values a buyer can measure: lid gap, cavity clearance, corner rebound, latch retention, stacking creep, empty weight.

First sample: the lid gap on a Fuze Pack Assembly
Cavity clearance decides how hands lift
Corner rebound after the drop
Latch retention and opening effort
Stacking and the closing checks
FAQ

1. First sample: the lid gap on a Fuze Pack Assembly

The first sample died at the bench before anyone argued about colour: a 0.8 mm feeler slid in at the corner where 0.5 mm was allowed, and slid in easily.

Pulling the tool found the cause: the land around the rim sat 1.2 mm narrower than the box mouth, so the latches bowed it rather than seating it. Corners cool faster and drag the land inward.

Measure three points, latches closed: centre front, both corners. Beyond 0.3 mm of spread, the hinge side lifts first.

Criterion	Instrument	Pass line	This sample
Lid gap	0.5 mm feeler	no entry at three points	0.8 mm at corner
Land flatness	straight edge plus feeler	spread within 0.3 mm	0.6 mm
Wall thickness	ultrasonic gauge	6.5 mm mean	5.6 mm at corner
Empty weight	platform scale	11.2 kg plus or minus 0.3	11.9 kg

2. Cavity clearance decides how hands lift

The second failure sat inside. The cavity was drawn 0.5 mm oversize per side, fine on paper and useless on the line: fingers cannot get under the part, so the operator tips the case out. Once tipping is routine, corners meet the floor far more often than any drop schedule assumes. A Fuze Pack Assembly needs its cavity derived from the pick action.

Fuze Pack Assembly: olive case open on a steel bench, egg-crate foam in the lid, six base cavities with grey wrapped blocks, white walls, shelving

A 1.5 mm gap to the wall is enough; tighter and mouth flash shaves the insert during loading.

0.3 to 0.5 mm clearance per side, proved with a shim;
pocket depth 1.2 mm above the part, room for lid foam;
finger notch 25 mm wide and 20 mm deep.

Depth is where buyers give ground: a shallower pocket feels tighter, and it is, because the part is pinched and thrown against the rim.

3. Corner rebound after the drop

The old routine dropped a case once from 1.2 m and looked for cracks. This round used six faces, three edges and one corner, dent measured inside 45 seconds, capped at 2 mm, then re-checked after 30 minutes for 85 percent recovery.

Rebound says more than the dent: ribs hold a dent down, but they cannot fake recovery, which tracks whether the chains are intact. From the same batch, the poor case cracked at minus 18 degrees Celsius, ten centimetres of split from a latch hole. Cold soak is the step schedules cut when the calendar is tight, and it catches what room temperature hides.

4. Latch retention and opening effort

The latches on this Fuze Pack Assembly read 780 N on the pull gauge, inside the drawing, and opened at 60 N. Anything that light opens when a sleeve brushes it.

The bridge angle on the tongue was too flat to pass over centre. Raising it 1.5 degrees put opening at 90 to 120 N with an audible click; past 150 N a gloved hand cannot press it, people use a knee, and the hinge takes the load.

Fuze Pack Assembly: closed olive case on concrete floor, four latches across the front, round pressure valve at centre, folding handle left, bare plant room

Latch type	Retention	Usable case length	Feel
Plastic over-centre	700 to 850 N	up to 800 mm	one finger, sharp click
Metal draw latch	above 1200 N	1000 mm and up	two fingers, strong spring

5. Stacking and the closing checks

Stack four high, 68 kg on top, 24 hours, then measure the bottom corners: 1.5 mm of creep is the ceiling. Four cycles between minus 20 and 55 degrees Celsius follow, the lid closed as it leaves the chamber to hear the gasket grab.

Weight gets skipped. The Fuze Pack Assembly weighed 11.9 kg against 11.2 kg on the drawing, all of it in the ribs; twenty on a pallet is 14 kg.

Six numbers in range and the round closes: new cooling circuit, raised bridge, thinner ribs, a sample that passed 12 days later.

Conclusion

The lesson was sequence, not craft: measure the interfaces, drop, weigh, and sign only when all six numbers sit inside their lines. Fit on a Fuze Pack Assembly is measured, not eyeballed, and a feeler gauge settles more than experience does.

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.