What drop height should a shockproof case be rated for?

A: Band by weight: 1.0–1.2 m at 12 kg, 0.8 m at 25 kg, or the carrier standard.

Is a thicker liner always better?

A: Gains flatten past 50 mm, and extra thickness only shrinks the cavity.

Can an empty case be drop tested?

A: Not as the only evidence. Ballast it to the real weight and centre of gravity first.

Can a shockproof case also be waterproof?

A: Yes, but test separately, or a drop-induced seal failure looks like a factory defect.

Does foam recover after one impact?

A: Mostly. EVA returns about eighty percent; three to five drops cost a permanent ten percent. ---

Shockproof Case Specifications: Drop Height, Liner and Clearance

Quick answer: A shockproof case is specified not by the word rugged but by three numbers: drop height, impact points, and the cushioning travel between load and wall. Fix those, and wall thickness, ribs and foam density follow.

Shockproof case specifications: three numbers
Drop height: from where, and how many times
Liner: density, thickness and compression
Clearance: how much between load and wall
Writing the three numbers into an RFQ
FAQ

1. Shockproof case specifications: three numbers

A shockproof case is an energy converter. A 12 kg case dropped from 1.2 m lands at 4.85 m/s with 141 J, absorbed within a few dozen millimetres. Acceleration is velocity squared over twice the travel: 25 mm gives about 48 g, 50 mm gives 24 g.

The numbers pull against each other: 1 mm more wall costs 2 mm of cavity. Work back from the load, never the outside.

Parameter	Sets	Typical value	Decided by
Drop height	Input energy	0.6–1.2 m by weight	Transport mode
Cushioning travel	Acceleration peak	25–50 mm per side	Cavity and liner
Liner density	Absorption	45–80 kg/m³	Load weight

The shell owes three things: no through-cracks, no popped latches, no direct impact path. A 3.0–3.4 mm polyethylene wall is enough once radii and ribs spread the load.

Shockproof case closed on a black chequered mat in a workshop, scuffed corners, wooden benches and grey-blue totes behind

2. Drop height: from where, and how many times

Height is banded by gross weight: 1.2 m below 9 kg, 1.0 m to 18 kg, 0.8 m to 27 kg, 0.6 m above that.

The corner is worst, since energy concentrates on a small area; the bottom edge is neglected, yet it loads the latches hardest. Drop each point three times: foam crushes a third of the way on the first hit and bottoms out on the second. Condition at minus 10 °C before repeating, because polyethylene turns brittle.

Gross weight	Drop height	Points	Main criterion
Under 9 kg	1.2 m	Corner, three edges, six faces	Corner cracks
9–18 kg	1.0 m	Corner, three edges, six faces	Joint gap, gasket
18–27 kg	0.8 m	Corner, three edges, base	Base set, liner
Over 27 kg	0.6 m	Corners and bottom edges	Handle roots

Pass criteria: no through-crack, latches engaged, gasket seated, liner compressed under ten percent. Miss one and the height stays off the datasheet.

3. Liner: density, thickness and compression

EVA at 60–80 kg/m³ rebounds slowly and suits heavy loads; EPE at 25–35 is cheap and takes a set after one hit; PU at 35–55 rebounds fast. Higher density absorbs more but passes more acceleration to the load, the commonest misjudgement.

Thickness is travel: 25 mm on the sides, 30 mm above and below, 40 mm sideways past 15 kg. Below 20 mm, foam is crushed in a 1.2 m drop. Cut pockets 3–5 mm shallower than the part and hold plus or minus 1 mm.

Shockproof case in black, three-quarter view, one rib along the lid centre, two latches pressing the joint, a grey gasket line showing

4. Clearance: how much between load and wall

Clearance is two gaps added: load to liner, liner to wall. Start at 25 mm per side and 30 mm at the top; too little and foam bottoms against the wall before compressing halfway.

Too much fails as well: a cavity 60 mm wider lets the load shift, and the second impact lands where no foam sits. Cavity length is load plus twice liner plus twice gap, so a 400 mm part needs 464 mm. An off-centre load turns in the air, and the face without ribs lands first.

Shockproof case standing upright in close-up, square handle raised, four vertical ribs from lid to body, fine grain texture

5. Writing the three numbers into an RFQ

An RFQ that says shockproof and extra thick leaves the supplier guessing. Pin five fields: weight and outside dimensions, internal cavity, drop height and impact points, test standard, liner material with density.

Add acceptance and cold conditioning, plus the residual liner thickness after compression, or two suppliers cannot be compared on one specification.

Shockproof case inside a van, a black strap across the lid toward a floor ring, ribbed rubber mat, white foam blocks around

Conclusion

Shockproof case specifications come down to one line: weight buys height, travel buys acceleration, clearance buys stability. Put all three on the RFQ.

This article covers container-side specifications and design implications only, not the handling, loading or use of the contents.