Who writes the acceptance standard for a waterproof protective case?

Answer: The user sets functional limits, the maker sets process limits, and the two become one document.

Can four gates become two?

Answer: Small lots can merge final and pre-shipment; incoming and in-process stay apart, since mix-ups and drift differ.

Who rules on defect class?

Answer: Quality rules and files it; the inspector only finds and records.

How long are first-off samples kept?

Answer: 12 months, from the same resin, mould and shift, or they prove nothing later.

What if the customer standard conflicts with the internal one?

Answer: Apply the stricter side, write the difference into the contract annex, then revise the internal document.

Waterproof Protective Case: Inspection Items and Judgement

Quick answer: A waterproof protective case is accepted through four gates — 12 incoming items, 9 in-process, 8 final and 4 pre-shipment — each with a named signer and a release condition. Critical defects are never accepted, and concessions need three signatures.

Four Inspection Gates
Defect Classes and Wording
First-Off Approval and Patrol Timing
Final Inspection Thresholds
Sampling and Reject Handling
FAQ

1. Four Inspection Gates

The weak point in acceptance for a waterproof protective case is rarely a thin standard; it is a gate with no named judge. Dimensions get measured, nobody rules between pass and rework, and the numbers stay on paper while the verdict stays verbal.

The order is fixed: 12 incoming items, 9 in-process, 8 final, 4 pre-shipment. No material enters the line before incoming release, no batch starts before the first-off is signed.

Gate	Timing	Items	Signer	Release
Incoming	Within 24 hours	12	Incoming inspector	Release sheet and COA
In-process	First-off, then every 2 hours	9	Patrol inspector	Signed first-off
Final	Every unit	8	Final inspector	Unit record in the system
Pre-shipment	Before loading	4	Storekeeper and QA	Shipping report filed

Gates do not substitute. A thorough final check cannot recover a material mix-up, and waving product through shifts its risk onto the next three.

2. Defect Classes and Wording

Classes decide what happens next, so the wording is settled before any threshold. A waterproof protective case carries three: critical breaks the protective function, major eats into sealing margin, minor is appearance and marking.

Waterproof protective case: two dark grey cases side by side on a wooden pallet inside a delivery truck, pale strapping crossed over them

Wording works with examples, not adjectives: the same flash is major on the sealing face and minor on the base.

Class	Examples	Action	Release
Critical	Body crack, latch fracture, handle pull-out	Isolate the lot, no rework release	Nobody; scrap or return
Major	Sealing-face flash, joint gap over 0.3 mm, handle set over 3 mm	Rework, then full re-inspection	Quality supervisor
Minor	Flash off the seal, marking off by 2 mm, ΔE 2–3	Record and release or sort	Inspector

Once written, classes are not re-cut before shipment; downgrading a major breaks the rework trail.

3. First-Off Approval and Patrol Timing

First-off approval is the gate most often skipped on a waterproof protective case, because it happens before the batch exists and produces nothing visible. The workable rule is three units per mould per shift, all items passed, one of them retained for 12 months.

First-off carries more than patrol: cavity tolerance ±1.0 mm, envelope ±1.5 mm, rim flatness within 0.5 mm. Those three decide whether the lid presses the gasket evenly. Patrol then runs every 2 hours on five units, reading joint gap, flash height, latch feel and unit weight, where a 3% swing signals wall thickness or melt flow drift.

4. Final Inspection Thresholds

Final inspection of a waterproof protective case does appearance and latches unit by unit inside 90 seconds: look inside and out, cycle the latches, confirm the marking.

Waterproof protective case: a large black case open and flat on a grey background, packed with olive and orange pouches, a green coiled hose

Performance carries four limits: handle static load of 30 kg held 10 minutes with no more than 3 mm permanent set, hinges still tight after 3,000 cycles, normal opening after a 0.9 m drop onto steel, and a gasket that stays seated across a 40 °C wall differential. Write the verdict as a sentence: "Unit 7, handle set 4.2 mm, major, rework and re-test" survives six months.

5. Sampling and Reject Handling

Sampling for a waterproof protective case follows GB/T 2828.1 at level II. At 281–500 units the sample is 50: critical zero-accept, major at AQL 1.0 with acceptance 1 and rejection 2, minor at AQL 2.5 with 3 and 4.

Lot size	Sample	Critical	Major, AQL 1.0	Minor, AQL 2.5
91–150	20	Zero accept	Accept 0, reject 1	Accept 1, reject 2
281–500	50	Zero accept	Accept 1, reject 2	Accept 3, reject 4
1201–3200	125	Zero accept	Accept 3, reject 4	Accept 7, reject 8

Rejects are isolated with a tag carrying lot, quantity and class. Reworked lots are re-inspected at the original sample size and only those items are released. Concessions take three signatures, three retained samples for 12 months and 36 months of records.

Conclusion

What holds in acceptance for a waterproof protective case is not the threshold table but the judge, the timing and the release at each gate. Limits can be negotiated, gates cannot be dropped, and classes can be refined but not rewritten on the day of shipment. Signatures, retained samples and records carry a waterproof protective case from paperwork onto the line.

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.