How many units should carry the equipment protection case tooling?

Answer: Injection from 300 up, rotomoulding below 200. At 120 units the rotomoulded total is 42,400 lower.

At 120 units is rotomoulding really cheaper than injection?

Answer: Yes. Tooling saves 85,000 while the unit price adds 420, so 120 units pay 50,400 more.

When does aluminium justify twice the price?

Answer: Shielding, weight and appearance. At 5.6 kg empty it is 1.6 kg lighter, which shows on air freight.

When is a soft bag sufficient?

Answer: Bumpered devices, no stacking, movement inside one site. Above 20 openings a month the zip fails.

How is the cost of one ingress calculated?

Answer: Parts plus downtime, 15,000 here, plus 3 person days of service time.

Can the case be reused after five years?

Answer: A rotomoulded shell takes new gaskets and foam for about 120 and runs three more years.

Five Year Bill: Equipment Protection Case vs Four Alternatives

Quick answer: An equipment protection case costs more at the counter and less over five years. At 120 units, rotomoulding needs a 35,000 mould and a 680 unit price for 116,600; injection moulding is 260 a unit but carries a 120,000 mould, landing at 159,000. Below 200 units the dearer box is the cheaper project.

The Equipment Protection Case Cost Spread Over Five Years
Injection or Rotomoulding: Where the Volume Line Sits
Aluminium and Soft Bags: Where They Stop Working
The Rework Bill Behind One Water Ingress
When to Walk Away
FAQ

1. The Equipment Protection Case Cost Spread Over Five Years

A testing company equips 120 handheld spectrometers, keeps them five years and ships six times a year. Three quotes arrive: 90 per carton with a timber frame, 260 per injection moulded case, 680 per rotomoulded case, 1,450 for aluminium.

On unit price it looks seven times dearer than cardboard. Put five years of spending on one sheet first.

Cost item	Once	Per year	Five years
Tooling	120,000 or 35,000	0	By route
Unit purchase	260 to 1,450	0	Times 120
Gasket renewal	0	35 each, every 2 years	About 2,100
Packaging	0	64,800 on cartons	324,000
Rework	0	See section 4	Adds up

The packaging row hurts: cartons are single trip, so six shipments of 120 sets a year reach 324,000 over five years.

2. Injection or Rotomoulding: Where the Volume Line Sits

The processes differ in tooling amortisation, not unit price. Injection tooling runs 120,000 with a 260 unit price; rotomoulding runs 35,000 with 680. Plotted together, the lines cross at 202 units.

Equipment Protection Case: closed olive green case on a rusty grey rack shelf, two side latches and folding handle facing the camera

At 120 units the project sits left of the crossing, so rotomoulding wins: 120 times 680 plus 35,000, or 116,600. Injection is 120 times 260 plus 120,000, or 151,200, and year four adds 30 replacements at 7,800, reaching 159,000. The extra 42,400 buys a thinner, lighter shell. Thinner is not automatically bad, but rotomoulded walls run twice the thickness and resist cracking after a knock.

Route	Tooling	Unit	120 units, five years
Injection	120,000	260	About 159,000
Rotomoulded	35,000	680	About 116,600
Aluminium	0	1,450	About 174,000
Carton and frame	0	90 per trip	About 324,000

Past 300 units it flips, as tooling thins and the 260 price takes over.

3. Aluminium and Soft Bags: Where They Stop Working

Both get sold as upgrades, and both have hard limits.

Aluminium: 1,450 a unit, 5.6 kg empty, dents fixed only by a panel swap at 180. It wins on shielding and appearance, loses on daily rack handling.
Soft bag: 180 a unit, 0.6 kg, foam as the only buffer, no rigid lip. Fine for a bumpered device that never stacks; stack two and the load sits on the shell.
Carton and timber: right for a one way export discarded on arrival, but it survives no third trip and no rain.
Plastic tote: cheap and stackable, with no seal at all.

An equipment protection case sits between them: heavier than a bag, cheaper than aluminium, and stackable.

4. The Rework Bill Behind One Water Ingress

Rework is not spent on the case, it is spent behind it. One failed seal took out two boards at 4,200 in parts and stopped a line for 6 hours at 1,800 an hour, another 10,800. That is 15,000 per event, enough to buy 57 injection moulded cases.

Equipment Protection Case: open olive green case on a steel bench, black egg-crate foam in the lid, four latches and a round pressure valve

Cartons leak three times in five years: 45,000 in rework on 324,000 of packaging, or 369,000. The rotomoulded route spends 116,600 with no rework. The gap is 3.2 times, not tens of percent.

A hidden cost is easy to miss: each ingress pulls a service engineer for 3 person days at 800 a day, 2,400 that never appears in a purchasing comparison.

5. When to Walk Away

An equipment protection case is not the answer everywhere.

For a one way export opened at the far end, cartons and timber at 90 beat every reusable option. Under 30 units, with devices carrying hard bumpers, a foam lined bag is enough. Inside one building, a plastic tote costs a sixth of the price.

Four triggers reverse it: over three trips a year, stacking two high, rain or dust, or a device worth over 20,000. Two of them and rework eats the price gap.

Conclusion

Count the equipment protection case over five years: tooling, consumables, rework and downtime together, and the dearest unit price is rarely the dearest project. At 120 units, rotomoulding lands at 116,600, injection at 159,000, cartons at 369,000. Read volume first, rework second, unit price last, and the equipment protection case stops being a line item argument.

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.