How many years should a custom reusable transport case be rated for?

Answer: Multiply annual trips by service years and add 20%. Six openings a day over 300 days for three years is about 5400, but full-case moves rarely pass 1200, and the two cannot be swapped.

Does a five-high stack test need a full 24 hours?

Answer: Yes. About seventy percent of creep lands in the first two hours, but the rest keeps accumulating, and only a 24 hour reading shows the long-term sag.

Does a 1:3 fold ratio weaken the load rating?

Answer: Only if the two duties share a path. The band folds, the posts carry the stack, so the rating does not depend on the fold.

What does a recycled content clause buy?

Answer: A traceable boundary. Once the ratio and grade are fixed, incoming inspection checks melt index and density, and an over-blended batch is rejected before it cracks in the cold.

Custom reusable transport case: 2000 cycles, 1.2 m drops

Quick answer: A custom reusable transport case is derived backwards from the life target, not picked from a catalogue. Cycle count and stack height set the load per unit, the load path sets thickness and rib pitch, and drop plus wash duty close the loop.

The load path that sizes a custom reusable transport case
Turning cycle counts into wall thickness and ribs
Drop energy and five-high stack loads
The structural cost of folding and recycled content
Wash duty and acceptance parameters
FAQ

1. The load path that sizes a custom reusable transport case

Four steps in a fixed order: stack height sets the base load, unit mass sets pressure, pressure and span set thickness, thickness and draft set ribs.

Step	Input	Output	Value
Stack height	2.4 m racking, 340 mm body	Base load	5 high, 120 kg at the bottom
Unit mass	8.5 kg body, 15.5 kg payload	Pressure	24 kg over 0.42 square metres
Thickness	Load and a 480 mm span	Panel gauge	3.5 mm, 4.2 mm at corners
Ribs	Mid-span, hinge clearance	Height, pitch	12 mm high on a 90 mm pitch
Closure	6 opens a day, 300 days	Pin, latch	6 mm pin, 220 N per latch

Reverse the order and a custom reusable transport case is trapped by its outline: corners thin to 2.8 mm, a rib recovers stiffness, a second mould appears.

Closures decide where a unit retires: the hinge loosens first.

2. Turning cycle counts into wall thickness and ribs

A cycle count is a life promise that converts into three wear limits: latch retention down no more than 15%, hinge clearance no more than 0.8 mm, panel wear no deeper than 0.2 mm.

Custom reusable transport case: a dark green case open on forest soil, two steel latches, folded side handle, blue mat and split logs inside

500 cycles covers in-plant handling on a shelf, so 3 mm with one rib is enough. 1200 cycles covers palletised freight, calling for 3.5 mm, two long-side ribs and a 5 mm hinge boss. 2000 cycles covers a closed route, where a replaceable corner insert takes the abrasion.

Gauge and ribs are not interchangeable. Going from 3.5 mm to 4.2 mm adds 20% weight for 44% bending stiffness; the same weight on ribs can pass 60%, at the cost of extra slides and longer cooling.

Ribs are cheaper than gauge but eat cavity volume.

3. Drop energy and five-high stack loads

In a 1.2 m six-face drop, a custom reusable transport case takes the energy at corners and edges, and the panel returns it. What counts is corner radius: R8 down to R4 shifts peak acceleration by 20 g.

Condition	Loading	Governing area	Acceptance
Six-face drop	1.2 m, one drop per face	Corners, hinge side	75 g or less, no release
Edge drop	1.2 m on three long edges	Mid-span	No through-crack, set under 2 mm
Five-high stack	120 kg for 24 h	Lid plane, posts	Creep under 1.5 mm
Forklift clamp	400 N on the side wall	Side wall centre	Dent under 1 mm

Twenty-four kilograms times five is 120 kg, spread unevenly: posts take seventy percent, the lid centre thirty. If the posts match the panel, tier four sags. A double wall at each post, 2.5 mm inside and 3.5 mm outside with a 6 mm cavity, adds 11% weight. Stacking and dropping pull in opposite directions. Stiffness goes into the posts, while the rib field in each panel stays free to buckle and recover.

4. The structural cost of folding and recycled content

A 1:3 fold ratio means the collapsed height is about a third of the open height: 340 mm down to 115 mm. It relies on a 45 mm double-wall band, 2.8 mm thick, that must survive 300 folds.

Custom reusable transport case: three olive-green cases on a concrete pad, the front one open over grey foam, two closed with double latches

The band is thinner than the panel because it must bend, so it becomes the weakest link of a custom reusable transport case. Let it fold and nothing else: under stack load the posts bear directly, with a 1 mm gap to the lid.

At 30% post-consumer resin a panel loses about 8% tensile strength and 12% notched impact, invisible at room temperature and both turning into cracks at minus ten. Recycled resin belongs in panels and lids only; hinge ears, latch seats and posts stay on virgin compound.

5. Wash duty and acceptance parameters

Every empty trip goes through a wash line, so the gasket and drains become consumables.

Rinse at 60 °C and 8 MPa, 90 seconds per face, no spot above 70 °C;
Four 8 mm drain holes, chamfered 0.5 mm;
Gasket groove 3.2 mm, assembled at 25% compression;
After 200 washes, gasket set no more than 20%;
Detergent limited to pH 6 to 9;
Acceptance: no standing water, no seepage, latch effort above 180 N.

The 60 °C ceiling comes from detergent and pressure, not the resin heat limit. Past it the gasket interval drops from two years to one, costing more per trip than the water saved.

Conclusion

The specification of a custom reusable transport case is a set of numbers that hold each other: cycles set the wear limits, the limits set gauge and ribs, stack height sets the post form, the fold ratio caps the band.

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.