Fifteen units, Missile Box or steel?

Answer: Steel. The 80,000 yuan mould adds 5,333 yuan to each of 15 cases and cancels the 8 year advantage.

Can an aluminium case replace a missile box?

Answer: Within 12 cycles and no side impact, yes; at 3 mm the wall dents and repair runs 600 yuan.

Rental is cheaper, so why does anyone buy?

Answer: Rental needs a backhaul. At 1,200 km the return leg adds 180 yuan, cutting the gap to 60.

Is the 8 year life a calculation or a claim?

Answer: Both. It assumes 40 plus cycles and 720 hours of spray; stack height and UV decide the rest, as on any missile box.

When does steel come out ahead?

Answer: Under 30 units a year, 3 years of life or less, dry storage: then 2,600 yuan wins before weight is counted.

When a Missile Box is the wrong buy, and what to use instead

Quick answer: Under 20 units, inside 1,200 km, used once: in those three cases something other than a missile box costs less. Four tables cover tooling, weight, cycle count and the 8 year sum, plus the three duties where nothing else survives.

Three signals that this order is not a Missile Box job
Welded steel instead: 80,000 yuan saved, 24 kg added
Aluminium and plywood: two hard limits
One-way shipments: rental and paper-wood options
Eight years against three: the whole-life sum
Three cases where only the Missile Box works
FAQ

1. Three signals that this order is not a Missile Box job

The first question is not the unit price, it is whether the order repeats. At 300 units a year an 80,000 yuan mould spreads to 8 yuan a case. On one order of 24 the same tooling is 3,333 yuan per case against a 4,800 yuan box, so it becomes 40% of the quote.

Signal one is batch size: rotomoulding starts at 20 units, and below that the price is mostly amortisation. Signal two is distance: 1,200 km one way, pallets of 1,200 by 1,000 mm, 2 loading points, and the case never nears its design load, so the extra wall buys nothing.

Signal three is the return path. Without a backhaul the cases become stock, and 5 high stacking holds 0.9 square metres of floor for years. Tooling ownership follows: pay the 80,000 outright and the mould travels with you; pay only a tooling charge and later batches add 30 yuan a case.

2. Welded steel instead: 80,000 yuan saved, 24 kg added

Item	Rotomoulded	Welded steel	Delta
Tooling	80,000 yuan mould	12,000 yuan jig	68,000 saved
Minimum order	20 units	2 units	18 fewer
Unit price	4,800 yuan	2,600 yuan	2,200 lower
Empty weight	38 kg	62 kg	24 kg more
Salt spray	720 hours	240 hours	480 fewer
Lead time	45 days	12 days	33 days faster

A Missile Box loses the first invoice and wins the eighth. On 20 units steel saves 68,000 yuan in tooling and 44,000 in price, yet the added 24 kg pays out at the dock: 300 cases a year over 1,200 km becomes labour and forklift hours.

Missile Box: olive green rotomoulded case closed on a white background, two latches and two folding handles, a round valve in the middle

Welds and paint are the second bill. A 1.5 mm shell carries 12 m of seam, primed at 30 yuan a metre; at 95% humidity rust starts at the seam ends after 2 voyages, and the 240 hour coating needs a coat every 2 years at 450 yuan.

Stacking decides it: 5 high, the bottom case carries 440 kg at a 110 kg payload.

3. Aluminium and plywood: two hard limits

Option	Panel	Empty weight	Cycles	Unit cost
Aluminium	3 mm sheet	29 kg	12	6,200 yuan
Plywood	12 mm board	34 kg	1	800 yuan
Rotomoulded	7 mm wall	38 kg	40 plus	4,800 yuan

Aluminium is light and reworkable, so a 1,050 mm cavity is easy to change, but a side impact dents the 3 mm wall and the liner no longer sits flat, 600 yuan a repair. Its anodised film is 15 microns; once cut, white rust creeps 20 mm in 3 months.

Plywood fails on moisture: at 95% humidity a 12 mm board swells for 6 months, diagonals move 4 mm and the gasket never seats. Export adds fumigation at 60 yuan with a 21 day certificate. One trip, then scrap.

Both limits fit in a line: to cycle the case, drop timber; to resist dents, drop thin aluminium.

4. One-way shipments: rental and paper-wood options

Option	Cost per case	Lead time	Reuse	Precondition
Rental	260 yuan	5 days	yes	backhaul network
Paper-wood	380 yuan	7 days	no	single trip
Rotomoulded	900 yuan	45 days	40 plus	300 units a year

Missile Box: sand case open on an outdoor wooden table, five foam compartments inside, folded canvas on cracked ground behind

Rental looks cheapest until the return leg is priced: beyond 1,200 km the backhaul runs 180 yuan a case, lifting the total to 440 and leaving a 60 yuan gap plus loss risk. Paper-wood is not uniform either: a 15 mm honeycomb holds 4 kN at 380 yuan, 5-ply corrugated only 2.2 kN at 210 and collapses at 3 high.

Two contract numbers matter: a 1,500 yuan deposit per case and losses charged at 4,800.

5. Eight years against three: the whole-life sum

Item	Rotomoulded	Welded steel	Delta
Purchase	4,800 yuan	2,600 yuan	2,200
Annual upkeep	300 yuan	900 yuan	600
Service life	8 years	3 years	5 years
8 year total	7,200 yuan	14,100 yuan	6,900
Cost per year	900 yuan	1,767 yuan	867

A Missile Box totals 7,200 yuan over 8 years; steel, replaced more than twice in that window, lands near 14,100. That is 867 yuan a year and 6,900 overall, before cash: 20 cases lock 96,000 yuan, costing 3,840 at 4% a year, or 192 a case, against 52,000 for steel.

The sum flips only when 20 units and a real 8 year life arrive together. At 200 units a year the mould share is 400 yuan, at 100 it is 800, and the annual cost reaches 1,700, level with steel.

6. Three cases where only the Missile Box works

storage from -40 to 60 degrees Celsius at 95% humidity, mixing yard and sea freight
a seal that holds -0.08 MPa vacuum or vents through a 0.2 bar valve
reuse after a 1.5 m drop, stacked 5 high, cycled beyond 12 times

Qualify any one of the three and the steel repaint cycle and plywood swell both fail. Sampling takes 3 steps: 6 faces dropped from 1.5 m, 2 hours of random vibration, 4 hours at -40 degrees Celsius; the latches must still need 150 N.

Conclusion

The three signals agree: treating a Missile Box as the default is what costs money on small batches, short hauls and single trips. Count the batch and the cycles, then the 8 year sum, and compare unit price last.

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.