What minimum order does a plastic equipment case supplier set?

Answer: 300 pieces for a 468 mm cavity, with a 1.4 multiplier below that. A new mould can be negotiated at 200 pieces, at a higher price.

How detailed should the match sheet be?

Answer: Net cavity on three axes, rib intrusion, coordinates and diameter of every hole, and the latch model. Appearance goes on the sample form.

Must all six checks run?

Answer: A new mould runs all six; repeat orders run drop, stack and airtightness, adding the rest when structure changes.

Is amortising tooling cheaper?

Answer: Under 3,000 pieces it keeps cash flow light; above that, a separate line is cheaper once the tool is paid off.

What do I ask first when quotes differ by 30 percent?

Answer: Foam density and hole process. Once a plastic equipment case supplier hears those two, the quote turns specific.

Can the 28 days shrink?

Answer: Yes, running matching and sampling in parallel saves up to 4 days. Beyond that you need an existing mould, with tolerance widened to ±1.0 mm.

Why plastic equipment case supplier quotes differ by 30 percent

Quick answer: When plastic equipment case supplier quotes spread 30 percent on one drawing, the gap usually sits in three matching details rather than machining cost: cavity tolerance, foam density and how holes are cut. Match the drawing, verify a sample, then settle minimum order and mould ownership.

Where the three differences sit
Drawing match: cavity and hole positions first
Six checks a sample must pass
Minimum order and who owns the mould
Delivery, payment and audit: three hard lines
Five traps in the quote sheet
FAQ

1. Where the three differences sit

Last month a client building inspection units needed a case with a 468 × 352 × 210 mm cavity for two probes and a harness, under 7.5 kg. Five replies came between 320 and 452 CNY, a 41 percent spread.

Same drawing, five prices.

Source	Cheap route	Costlier route	Effect in use
Cavity tolerance	±1.5 mm	±0.5 mm	Brackets rattle
Foam insert	18 kg/m³ sponge	25 kg/m³ high density	Collapses in months
Holes	Punched, burr left	CNC milled, chamfered	Jacket cut
Latches	Bought-in generic	Dedicated mould	Grip fades at 2000 cycles
Wall	3.0 mm uniform	4.5 mm plus ribs	Lid sags

Two of the five itemised foam and holes; the rest quoted one figure per case.

Cavity tolerance is the first hidden line: ±1.5 mm to ±0.5 mm adds 8 to 12 percent and decides whether the probe sits still.

Foam and holes are the other two. An 18 kg/m³ sponge under 7.2 kg prints within three months; a punched hole burr wears a jacket through.

2. Drawing match: cavity and hole positions first

Matching is not sending a drawing and waiting. The plastic equipment case supplier checks cavity size, rib intrusion and hole-centre distance against your unit.

Plastic equipment case supplier workshop: navy case open on a steel bench, grey foam insert with coiled cables and black modules, shelving behind

Start with a match sheet: allowance on three cavity axes, rib clearance, coordinates of every hole, and which side the harness exits. On a 4.5 mm wall, rib roots thicken to 6 mm and take 3 to 5 mm of clearance; unmarked, the unit hits them at trial fit. Holes closer than 12 mm to a corner sink, so the plant shifts them or adds a pad. Both sides sign, then quoting starts.

3. Six checks a sample must pass

Sampling takes 7 days and yields three cases that a plastic equipment case supplier puts through the checks below.

Drop: 1.2 m, once per face, three corners, no cracks.
Rain: 30 minutes on a 15° incline, no pooling.
Temperature: 4 hours at -20 ℃, 4 hours at 60 ℃, two cycles.
Stack: five units for 24 hours, set under 2 mm.
Latch life: 2000 cycles, grip loss under 20 percent.
Airtightness: -20 kPa held 60 seconds, drop under 5 percent.

Repeat orders take drop, stack and airtightness; a new mould takes all six, logged in the first-article report. Sample 5 percent per batch, counting destructive units into the order.

Airtightness is the check most often skipped, and one unsealed seam grows mould inside a case within two weeks.

4. Minimum order and who owns the mould

Three hundred pieces is the usual minimum; below that, the plastic equipment case supplier applies a 1.4 multiplier.

Plastic equipment case supplier inspection bench: close-up of a translucent grey latch on a pale case, glass slides nearby, lab equipment blurred behind

A 468 mm cavity needs a 2.4-tonne mould on a 550-tonne machine, costing 52,000 CNY, or 17.3 CNY per case across 3,000 units. Ask whether the mould number, storage address and collection notice appear in the contract.

The tool is rated near 120,000 shots, after which venting carbon builds up. A written maintenance interval beats arguing over 2 percent.

5. Delivery, payment and audit: three hard lines

A delivery date becomes enforceable only once it is split.

Stage	Days	Deliverable	Payment
Match and sign-off	6	Signed sheet, model return	20%
Sampling	7	3 samples, six records	0
Production	11	300 pieces, batch sheet	70%
Inspection	4	Inspection record, packing list	10%

The stages total 28 days. The clock starts when the signed sample returns, not at order placement.

Payment runs in three parts: 20 percent after matching, 70 percent against dispatch notice, 10 percent 15 days after acceptance. A supplier demanding full prepayment is short of capital, so raise the risk.

Audit two rooms of the plastic equipment case supplier: the foam shop and the hole-cutting cell. A punch press, not a mill, tells you what the hole edges will look like.

6. Five traps in the quote sheet

One: the set price. Foam and dividers billed separately, 20 percent above quote.

Two: split tooling. Development and trial fees as two items, the second after you sign.

Three: paid revisions. Holes changed at 800 CNY each; three changes cost a fixture.

Four: the refund threshold. The sample fee is refundable at 500 pieces, not 300.

Five: a seven-day validity. Locking the price costs 3 percent, and deadlines kill comparison.

Conclusion

A 30 percent spread rarely comes from machining rates. It comes from a loose match sheet, a sample that never saw an airtightness check, and a mould whose ownership was never written down. Picking a plastic equipment case supplier starts with whoever fills in that sheet.

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.