Does a case factory audit have to be on site?

Answer: A first pass runs on video, but 4 of the 8 checks need a visit.

How many auditors, and what tools?

Answer: Two people with digital callipers, a 1 g scale and a torch; the plant's rig and CMM are fine with certificates.

What if the case factory has no 1000 t machine?

Answer: The product follows the machine. A 650 t press handles up to 500×320 mm; an 800×500 mm order goes to a subcontractor.

How often is the audit repeated?

Answer: Every 12 months while production is stable, and within 30 days of any recall, resin change or mould change.

Which point is easiest to fake?

Answer: Regrind ratio, inferred from colour shift and part weight.

Auditing a Case Factory: Eight Things to Check

Quick answer: A case factory audit needs eight checks and 120 minutes: clamp force against projected area, resin grade against a regrind cap, 2.8 to 3.2 mm walls at five points, and a 20 kPa leak test losing under 0.5 kPa in 60 seconds.

Eight points and a two-hour route
Tonnage against projected area
Resin grade, regrind and part weight
Leak test, hardware and salt spray
Gauges, first article and sampling
5S, the yard and three red lines
FAQ

1. Eight points and a two-hour route

A case factory audit wastes half a day when it opens in a meeting room. Six of the eight checks exist only on the floor. Spend the 120 minutes as 35 in moulding, 15 in resin, 25 at the leak bench, 10 in hardware, 20 in quality and 15 in the yard.

Point	Look at	Weight	Fail line
Machine	Tonnage, moulds	15	Clamp force short
Resin	Grade, regrind	15	Regrind above 30%
Wall, weight	5-point calliper	15	Under 2.6 mm
Leak	Decay rig	15	Decay above 1 kPa
Hardware	Latch source	10	No purchase record
Gauges, FAI	Report, certificate	10	No FAI report
5S, yard	Clearance, stack	10	Work on the floor
Outgoing	AQL records	10	No sampling record

Above 80 moves to samples, 60 to 79 returns after corrective action.

2. Tonnage against projected area

Tonnage is the figure a case factory audit most often hears rounded up. Clamp force must cover the largest projected area at 0.4 t/cm² of cavity pressure: a 520×380 mm case projects 1976 cm², needs 790 t, and runs on a 1000 t machine at 21% margin. Below 15%, flash shows along the long side first.

Case factory audit check on latches and handle: closed black case on white, two red catches, recessed grip, four moulded feet

Tonnage	Max projected area	Typical case
250 t	600 cm²	300×200 mm
400 t	1000 cm²	400×250 mm
650 t	1600 cm²	500×320 mm
1000 t	2500 cm²	620×400 mm
1600 t	4000 cm²	800×500 mm

Mould count matters: 12 machines with 2 above 1000 t cannot carry 800×500 mm cases monthly.

3. Resin grade, regrind and part weight

Three moves in the resin store: open a bag, read the grade, ask about regrind. Homopolymer PP for a case body sits at a melt index of 8 to 12 g/10min.

Set the regrind cap by part: 20% for structure, 10% for sealing faces and latch seats, 5% for visible surfaces. A case factory promising 10% and running 30% is caught by weight and colour: a batch-to-batch ΔE above 1.5 means the ratio moved. Wall thickness takes five calliper readings: a nominal 3.0 mm wall passes between 2.8 and 3.2 mm, and any spot under 2.6 mm fails.

Part weight backs the calliper up: a 620 g case carries ±3%, or ±18.6 g, and ten parts from one mould spreading more than 25 g point to unstable melt or pack pressure.

4. Leak test, hardware and salt spray

Leak tightness yields a number on the spot. Charge the case to 20 kPa, hold 60 seconds, accept a drop of 0.5 kPa or less; past 1 kPa the gasket has stopped sealing.

Case factory audit measurement of the shell: case standing upright, handle across the top, two red latches, four square feet

For IP67 the case sinks to 1 m for 30 minutes, then the inside is wiped and inspected, with a timer and depth scale on the tank. Hardware is traced by purchase slip: latches, hinges and valves carry a supplier and a batch; 304 springs must survive 48 hours of neutral salt spray; carbon steel below 8 μm spots within one voyage. A latch cycled 500 times may lose 15% of closing force at most. Gaskets sit near Shore A 55, and more than 2 joints fails the bench.

5. Gauges, first article and sampling

A first article report is the hard currency of a case factory audit. Twelve key dimensions, covering cavity size and latch seats, are measured on a CMM to 0.02 mm within 48 hours; a report with no values is not a report.

Gauges must be traceable, and the usual miss is a pressure gauge untouched for three years. Sampling runs on AQL: a 1200-piece lot at level II takes 80 pieces, majors at 2.5 accept 5 and reject 6, and 3 pieces stay on file for 12 months.

6. 5S, the yard and three red lines

Read 5S from the floor: work in progress sits 150 mm up on stillages, aisles stay 1.2 m clear, and moulds stand on numbered racks.

In the yard, finished cases stack 3 high with board on top. Three red lines end the visit: regrind above 30%, leak decay above 1 kPa, no FAI report.

Conclusion

A case factory audit earns its keep on four pass-or-fail numbers: clamp force matched to projected area, resin grade matched to the regrind cap, wall thickness inside 2.8 to 3.2 mm at five points, and a 20 kPa leak test losing no more than 0.5 kPa in 60 seconds. Clear those and price and lead time become a real conversation; miss them and a low price only shifts rework cost to your warehouse. Re-audit every 12 months, and within 30 days of a resin, mould or recall event.

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.