The instrument allows 40 g. What input should the shaker run on our Shockproof plastic instrument case?

Answer: Work back from transmissibility. At a resonance figure of 3, input cannot exceed 13 g.

Can a drop test replace the shaker?

Answer: Only for the shock item. Drop energy sits inside 2 ms and cannot show the 20 to 200 Hz gain.

How long is a report valid?

Answer: Twelve months while design, insert and supplier stay unchanged. A new foam density restarts the type test.

We changed insert supplier only. Is a full retest needed?

Answer: No, but vibration and shock are mandatory. Same density with different hardness can halve transmissibility.

Is transmissibility taken once or three times?

Answer: Mounting face over table, maximum of three axes, repeated three times. More than 15 percent scatter means a loose mounting.

Sealing failed but the customer says the duty is mild. Can it ship?

Answer: Outdoor or cold-store duty needs rework; a conditioned workshop allows concession with a lower IP marking.

Shockproof plastic instrument case: 3 channels, 18 shocks

Quick answer: Acceptance of a Shockproof plastic instrument case is judged at the instrument mounting face, not at the shell. Three channels go on the table, the case base and the mounting face; a transmissibility above 3 fails, and the shock run is a 15 g, 11 ms half-sine on three axes.

Three Layers of Criteria
Mount It on the Instrument Face
Sweep 20 to 200 Hz
Shock at 15 g, 11 ms
Sealing and Condensation Checks
Three Routes for a Failed Unit
FAQ

1. Three Layers of Criteria

Most failed negotiations start with three layers collapsed into one phrase about the standard. The environmental standard sets tests and severity, the method standard sets mounting and sampling, the contract sets sample size and disposition.

Layer	Typical documents	What it fixes
Environmental	GJB 150.16A, MIL-STD-810H	Tests and severity
Method	IEC 60068-2-27, 60068-2-64	Mounting, sweep, sampling
Ingress	IEC 60529, IP67	Dust and short immersion
Delivery	Contract annex, drawing notes	Sampling, pass mark

The usual gap is the third layer. A report stating the unit functioned normally, with no mounting-face peak and no transmissibility figure, reads as both a pass and a fail.

2. Mount It on the Instrument Face

Pick the wrong point and everything downstream is wasted. Shell response depends on ribs and the gasket groove, so spots on the same shell differ by 40 percent; the instrument is loaded where it meets the insert.

Shockproof plastic instrument case: black shell open on a woodworking bench, egg-crate foam in the lid, knob board, pliers, screwdrivers and a coiled cable inside

Three channels divide the work: table as input reference, case base for structural response, mounting face for the verdict. Keep a service loop in the cable; a taut lead transmits force.

Sample at 10 kHz or above, anti-alias filter at 0.4 times the rate, both in the report.

Channel	Position	Range	Role
CH1	Table	50 g	Input spectrum
CH2	Case base	200 g	Structural gain
CH3	Mounting face	500 g	Pass or fail

Calibrate the three sensors as one batch at 10 mV per g; mixed batches bias transmissibility by more than 10 percent.

3. Sweep 20 to 200 Hz

Road energy sits between 20 and 200 Hz: suspension at 2 to 8 Hz, floor panels at 10 to 20 Hz, frame coupling at 60 to 200 Hz. A resonance of the Shockproof plastic instrument case in that band is amplified on every kilometre.

Sweep 5 to 500 Hz at one octave per minute, 0.5 g input, one pass per axis. The pass mark is a transmissibility of 3 or less at resonance; above that the insert has stopped isolating.

Resonance needs a dwell: 10 minutes either side of the peak, then sweep again. A shift above 10 percent means foam compaction or a loosened latch.

4. Shock at 15 g, 11 ms

Shock runs as a half-sine at 15 g and 11 ms, three shocks in each direction on three axes, 18 in total. That matches roughly a 0.8 m drop, the common event at a tail lift.

Shockproof plastic instrument case: black shell on an old timber floor, lid ajar, two latches and a moulded handle, two acoustic guitars behind

Three conditions hold together: mounting-face peak under the instrument limit, insert set under 1 mm, latches and hinges intact.

With a 40 g instrument limit, a 15 g input leaves 2.6 times margin; an insert that amplifies the peak to 45 g turns that margin negative. Strip the insert afterwards: crushed foam cells and a base pad down from 15 to 12 mm count as set.

An intact shell with an over-limit mounting face accounts for over half the failures in practice: a cargo case is judged on cracks, an instrument case on the g-forces it passed on.

5. Sealing and Condensation Checks

Vibration is not the only risk. Sealing is checked to IP67: hold 20 kPa for 60 seconds with no more than 0.3 kPa drop, or immerse 1 m for 30 minutes. Gasket compression stays at 25 to 30 percent; at 50 it seals this year and not the next.

Condensation hides better. Run five cycles between −20 °C and 55 °C at four hours each, then require no water marks and under 0.5 percent insert growth; a 0.1 mm gasket gap lets moisture in within a day.

Pressure valves are the blind spot: a relief valve can leak at 20 kPa alone, so plug it and test the shell, or test the valve.

6. Three Routes for a Failed Unit

A failure is not automatically a rejection. Sort by defect type and record every case.

Rework: transmissibility 3 to 5 with an intact shell; insert density 45 to 60 kg per cubic metre, base pad 8 to 15 mm
Concession: transmissibility above 3 with a delivery radius under 300 km; cut the load 20 percent, mark it restricted, get written acceptance
Rejection: transmissibility above 5, a through-crack, or a latch that opens during shock
Records: unit number, sensor position, spectra and shock traces kept for three years

Write those boundaries into the contract. Say only that failures are returned, and every problem drifts toward concession.

Conclusion

Acceptance of a Shockproof plastic instrument case rests on mounting-face acceleration, not on a report paragraph. Three layers set the tests, sensor position sets the truth, transmissibility sets the verdict, three routes set what follows for the Shockproof plastic instrument case.

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.