Which raw records must a temperature-controlled case file contain?

Answer: Probe map with IDs, valid calibration certificates, measured transfer time per cycle and unedited curve files.

If the sample passed IEC 60068-2-14, must a temperature-controlled case in production be retested?

Answer: Yes, with a smaller scope: the sample proves design, production proves process stability, so first article plus short-cycle lot sampling.

A case is marked both IP65 and IP67. Which governs?

Answer: The duty in the contract, not the label. Test IP66 for washdown, IP67 for credible immersion.

How does a buyer verify a supplier's insulation curve?

Answer: Run one independent test on a case of the same specification and compare hold deviation.

Temperature-Controlled Case Tests to MIL-STD-810H, IEC 60068

Quick answer: Acceptance of a temperature-controlled case should rest on three things a third party can re-check: the clause cited, the curve recorded, the sample kept. This article gives the clause, the on-site method and the pass line for thermal cycling, insulation, ingress, vibration and drop.

Three things to fix before acceptance
Thermal cycling: dwell and transfer limits
Insulation: reading pull-down and recovery curves
Seals and ingress: jet spray and pressure decay
Vibration and drop: levels, fixtures, read-out
Disposition: rework, concession, batch hold
FAQ

1. Three things to fix before acceptance

Most disputes about a temperature-controlled case are not about a broken product but about two parties meaning different things by pass: the buyer pictures a duty cycle, the supplier holds an outgoing report.

The bridge is a clause number: IEC 60068-2-14 Na and Nb for cycling, MIL-STD-810H 514.8 for vibration, 516.8 for drop, IEC 60529 for the IP code. Then a sealed sample with measured wall thickness and latch batch, and records that survive review six months later: equipment ID, probe positions, ambient temperature, untouched curve file. Leave one open and later tests become opinions.

Check	Clause	On-site method	Pass line
Thermal cycling	IEC 60068-2-14 Na	Two chambers, 3 hours each	No cracking or set after 5 cycles
Insulation	Contract curve	Log cavity centre and wall	Drift under 2.5 °C over 10 hours
Ingress	IEC 60529 IP67	Immersion 1 m, 30 minutes	No water or mist inside
Vibration	MIL-STD-810H 514.8	1 hour per axis	Latches shut, liner in place
Drop	MIL-STD-810H 516.8	Edge, face, corner at 1.2 m	No through-crack, lid closes

The pass line is a floor, not a target: put a floor plus tolerance in the contract.

2. Thermal cycling: dwell and transfer limits

Variation between laboratories sits in dwell and transfer. Under IEC 60068-2-14 Na the sample must be stable before the dwell starts: a change under 1 °C within 3 minutes at the reference point. Nb allows transfer before stability. A temperature-controlled case carries heater film and cold packs, so a wall-mounted probe runs minutes ahead of the cavity centre.

Temperature-Controlled Case: a long white case on a galvanised rack beam, two latches, moulded end handle, tan gasket line, strip lights

Transfer time is where protocol meets reality: five minutes in the plan becomes seven in a corridor. The record sheet needs a measured transfer time column; an excursion beyond the limit invalidates that cycle.

3. Insulation: reading pull-down and recovery curves

Judge insulation on curve shape; a single number can come from any construction.

Start point: load the case, measure the cavity centre, record the measured value.
Pull-down: active units log the drop per minute; passive units log start and end.
Hold: 10 hours, one reading per hour, keep the worst deviation.
Recovery: from -25 °C into a 23 °C room, log every 15 minutes.
Verdict: hold within 2.5 °C, no pooled condensate within 90 minutes.

Step three is the one most often faked: a probe pushed into foam reads foam. Suspend it at the cavity centre, 50 mm clear of the wall. Wall thickness then decides whether the hold stays flat: 38 mm is a common nominal, 36 to 40 mm is normal scatter, and a point below 34 mm means uneven powder in the rotomould, which shows on the curve as 4 to 6 °C a day.

4. Seals and ingress: jet spray and pressure decay

Ingress disputes stall between IP65 and IP66: water jets against powerful water jets, different pressure and nozzle. For IP66, fix four items on the record: nozzle bore, pressure, spray distance, time per face.

Temperature-Controlled Case: a cream case open on a worn bench, black foam in the lid, cut-out pockets, grey pouch, coiled cable, wrenches

A workable setup is a 12.5 mm nozzle at 100 kPa from 3 m for 3 minutes per face. Open it at once and check the corners, latch seats and gasket root.

Log the gasket separately: 55 to 65 Shore A at about 30% compression holds; past half compression the profile takes a set and leaks within six months. For line sampling, charge to 3 kPa and read the drop over 60 seconds; beyond 0.5 kPa the seal fails.

5. Vibration and drop: levels, fixtures, read-out

Random vibration follows the transport mode: road sits near 1.04 grms, rail and air differ, and mixing them means nothing. MIL-STD-810H 514.8 gives the method, not the level, so spectrum and duration per axis belong in the contract.

A flexible fixture eats vibration, so ask for fixture photographs. Drop testing follows 516.8 at 1.2 m, edge, face and corner onto steel, read on structure and function.

6. Disposition: rework, concession, batch hold

Disposition has three buckets; blanket rejection is as indefensible as blanket release. The split follows whether a defect is reversible and whether it touches function.

Type	Applies to	Follow-up	Sign-off
Rework	Thin wall, mis-set latch seat, loose foam	Repeat the failed test	Quality engineer
Concession	Colour drift, flow marks, shifted label	Signed waiver, 5% cap	Buyer and quality
Hold	Seal failure, dead module, through-crack	Line stop, root cause, lot re-test	Programme manager

Rework cannot stop at cosmetics: the unit repeats the test that failed. Batch hold usually points at mould or assembly.

Write the outcome as one line: rework, concession or hold, plus owner and date.

Conclusion

Acceptance turns a vague word into reproducible numbers: clause, probe position, transfer time, pass line. Split nonconformity into rework, concession and hold and the loop closes. Whether a temperature-controlled case meets its specification is decided by curves and records, not by a promise.

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.