Why does rugged plastic storage case OEM work start at 300 units?

Answer: It is where tooling stops dominating unit price: 140 CNY at 300 units against 420 at 100, a share falling from 51 to 8 percent.

Who pays for the mould, and is it charged again?

Answer: Under OEM the buyer owns it and repeats carry no tooling charge. Under ODM the supplier owns it, so fix a buyout price.

Can sampling skip the SLA print?

Answer: Yes, but the risk moves into the mould: a print costs 1,800 CNY, while altering a parting line costs 26,000 CNY and 12 days.

Which line of a rugged plastic storage case OEM quote needs the closest reading?

Answer: Moulding: hourly rate, cycle and cavity count must appear separately, since a lump sum absorbs scrap.

Can 49 days be compressed?

Answer: To about five weeks. Tooling and repair overlap; trial stabilisation and inspection do not.

Rugged Plastic Storage Case OEM: Quotes, MOQ and Lead Time

Quick answer: A rugged plastic storage case OEM quote is six cost blocks plus overhead. MOQ of 300 units is where a 42,000 CNY steel mould stops dominating unit price at 140 CNY; 26 of the 49 days to shipment are tooling and repair.

How a Rugged Plastic Storage Case OEM Quote Is Built
Where OEM and ODM Responsibility Divides
The Three Sampling Steps
Setting the Trial Moulding Window
Factory Audit Evidence
FAQ

1. How a Rugged Plastic Storage Case OEM Quote Is Built

A rugged plastic storage case OEM quote is six cost blocks plus overhead. Five fall slowly with volume; tool amortisation falls in a straight line.

On a 620 × 420 × 260 mm case at 3.2 kg, resin at 11.5 CNY per kilo is 37 CNY, and a 960-tonne press at 600 CNY per hour on a 105-second cycle adds 18 CNY of moulding. A 42,000 CNY single-cavity P20 mould adds 140 CNY at 300 units and 42 at 1,000, landing the case at 276 and 166 CNY. Decomposition, not a quote.

Cost block	300 units	1,000 units
PP resin	37 CNY	35 CNY
Moulding	18 CNY	18 CNY
Hardware	26 CNY	24 CNY
Seals and foam	14 CNY	13 CNY
Assembly	11 CNY	10 CNY
Tool share	140 CNY	42 CNY

2. Where OEM and ODM Responsibility Divides

What differs is not who draws the case but what gets measured on failure. OEM is accepted against drawings, so an oversized dimension is the supplier's problem. ODM is accepted against performance, so dimensions are the supplier's call, yet a failed drop test still lands there.

Rugged plastic storage case OEM: black case open on a timber bench, compartment foam inside, a scanner, batteries and cable beside it, orange racks behind

Tool ownership is the grey zone. A 65,000 CNY two-cavity mould the supplier funds is bought out on remaining shots: total divided by 300,000 design shots, times shots run, near 48,000 CNY at 80,000. Set ECN rules early: a new rib is free, changing the parting line costs 60 percent of rework.

3. The Three Sampling Steps

An SLA print checks proportion and latch feel, a machined prototype checks assembly, and first-article inspection checks whether the moulded part is still the same case. Skip one and the fix lands on steel.

The print runs five days at full scale, 2.5 mm walls. The prototype takes eight days, closing force held at 25 to 35 N. Inspection takes two days over twelve dimensions: depth at ±0.8 mm, lid gap under 0.5 mm, mismatch under 0.3 mm. Sampling costs 15 days and 19,000 CNY, cutting rework from three rounds to one.

4. Setting the Trial Moulding Window

Trial moulding fixes the process window that goes onto the card the floor follows every shift.

Rugged plastic storage case OEM: grey case open on a workshop bench, instrument foam and wiring inside, three foam inserts, a knife and steel rule

The card holds clamp force at 650 tonnes, melt at 225 °C, mould at 45 °C, packing at 60 MPa, cooling at 28 seconds and cycle at 105 seconds.

Measure shrinkage on the grade, never a datasheet. Homopolymer PP sits at 1.6 to 2.0 percent; at 1.8 a 620 mm case loses 11.2 mm, so the cavity goes to 631 mm. Keep first-shot against last-shot dimensions and a twelve-point wall map; drift above 0.4 mm means uneven cooling.

5. Factory Audit Evidence

An audit rests on three proofs: machines matched to records, documents that can be looked up, material traced backward.

Check	Pass criterion	Common gap
Machine list	8 or more presses, 400 to 1,300 t	Tonnage overstated
Tool register	Shots counted, service every 5,000	No records
ISO documents	ISO 9001 number verifiable	Scope excludes moulding
Incoming traceability	12-month retained samples	None kept
Records	2-hourly patrols with numbers	Boxes ticked

A 1,300-tonne press runs a 620 mm case comfortably; 650 tonnes adds 15 seconds. PP samples are kept 12 months at 500 g per lot. Settle rugged plastic storage case OEM lead time here: 3 days drawing freeze, 20 tooling, 5 T1, 6 repair, 12 production, 3 inspection, 49 total. Reaching 35 means overlapping tooling with repair at 2,800 CNY per machine day.

Conclusion

Good buying separates one-time from recurring cost: the mould is paid once, amortisation follows volume, the window comes from data. Contract those three and quotes become comparable. That is how a rugged plastic storage case OEM project becomes a plan you can commit to.

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.