Should pad hardness in a testing equipment protective case follow machine weight?

Answer: Yes, by load per support point, not total. Divide weight by the point count, then pick density; 90 and 130 kg/m³ differ twofold.

Is a 200 km trip too short for three level readings?

Answer: Two are enough, empty and loaded. Skip the re-torque but re-verify repeatability on arrival, because short trips are not automatically gentler.

Can one testing equipment protective case hold two machines?

Answer: Yes, if each is fixed independently, they never touch, and 40 mm of buffer sits between them.

Why carry a certificate copy in the case?

Answer: It is the baseline for arrival checks. The original stays at the institute, so the copy tells you whether a deviation came from transport.

Can the case replace a timber crate and skip fumigation?

Answer: Yes, a plastic hard shell is not wood packaging. It still has to stack, so a mid-layer case going by sea should be proven at 1.2 tonnes.

How a testing equipment protective case carried a CMM 380 km

Quick answer: A 700×1000×600 mm CMM travelled 380 km for annual calibration, and the testing equipment protective case was the easy part. Pad compression, bolt order and second lifts decided the result. What follows: 25 mm pads, 6 N·m diagonal torque, a 0.02 mm/m level check, arrival re-verification.

What this testing equipment protective case had to carry
Loading the CMM: pad thickness and bolt order
Spectrometer and accessory bays
Level and pad compression checked on site
Counting the second lifts
Paperwork inside the case and re-verification on arrival
FAQ

1. What this testing equipment protective case had to carry

A tier-two automotive supplier in Suzhou sends a four-year-old CMM 380 km for annual calibration. Two earlier trips went in a timber crate, and the Z-axis error arrived at 4.7 μm instead of 2.1 μm — inside tolerance, but enough for an auditor to ask why.

Three dimensions came first: door clearance 1.6 m, tail-lift height 0.9 m, lifting-point spacing 1.2 m. They decide whether the machine travels assembled.

The load is four items.

Item	Net weight	Envelope mm	Sensitive point
CMM main unit	620 kg	1180×1420×2050	guideways and glass scales
Control cabinet	45 kg	600×800×1200	board connectors
Portable spectrometer	18 kg	480×380×220	optical window
Probe and master ball	3.2 kg	210×160×90	ruby tip

The envelope of the testing equipment protective case is set by the longest item, the interior split by the most sensitive one.

2. Loading the CMM: pad thickness and bolt order

A cast-iron base cannot sit straight on the case floor. Without continuous bearing, four uneven contacts twist the column.

Testing equipment protective case: a long flat brown shell lying closed on a cabin porch deck, both latches shut, scuffed lid, firewood and boots behind

Padding is 25 mm closed-cell EPDM, cut into 120 mm × 100 mm blocks at six points, never one sheet. A sheet leaves the base spanning air and turns the pad into a drum skin.

Thicker is not better; past 30 mm the machine rocks.

Torque goes diagonally: two diagonal points at 6 N·m, the centre pair at 2 N·m preload, the last two re-tightened after two hours because the foam creeps 1 mm. Four hours on, two points had fallen to 5.2 N·m.

One pass never holds.

3. Spectrometer and accessory bays

The main unit takes seven tenths of the interior; the rest of the testing equipment protective case goes to the spectrometer and accessories, listed rather than tabulated because each is counted as it goes in.

Portable spark spectrometer, 18 kg, own bay with 15 mm clearance
Electrode stand and spark stand on the shelf above that bay
Four reference blocks, each in a slot 12 mm deep
Two argon hoses coiled to 200 mm and tied to the wall
Mains and signal leads in one bundle, 50 mm slack at each end
Manual and certificate copy in a dry bag on the top layer
Two spare probes, ruby tips up, in foam pillars

Bays exist so counting is possible. Read the list aloud, then close the lid; a missing part surfaces on arrival and costs two days.

4. Level and pad compression checked on site

Packing is not the finish line. Before the lid closes, level is read again at four points on the worktable.

Testing equipment protective case: olive green shell open on a cabin deck, orange dividers making four bays, flat lid liner, two latches and side knob

The spread must stay inside 0.02 mm/m. Tolerance is 2.5 μm, and every 0.01 mm/m adds about 0.4 μm of cosine error over a 1 m stroke, leaving no margin for road vibration.

Compression is read at the same time. A 25 mm pad under 103 kg per point should compress under 3 mm.

Order matters too. Empty case first, machine in second, two hours after torque third. The readings went on one sheet: 0.008, 0.014 and 0.011 mm/m. If the third is worse than the second, look at the bolt order, not the shell.

5. Counting the second lifts

Count the lifts: four on this route — pallet truck, tail lift, tail lift, forklift — and two involved a turn.

Straight runs peaked at 1.8 g; a turning lift peaked at 3.4 g, because one side leaves the ground and load runs through the pad edge.

Avoid the turn.

Tilt indicators stayed clear; a 20 mm corner scuff showed a grazed van pillar.

6. Paperwork inside the case and re-verification on arrival

Paper travels too inside the testing equipment protective case: certificate copy, packing list, torque record and level readings, in a dry bag.

Three checks on arrival.

Check	Criterion	Recorded by
Repeatability	within 1.0 μm of factory value	laser interferometer, three points
Indication error	within 2.5 μm over full range	five-step gauge block comparison
Probe trigger force	within 0.02 N in any direction	force gauge, probe by probe

Repeatability moves first. It follows shell stiffness, but also pad shift: 5 mm of shift can cost 0.6 μm.

Conclusion

Most of a calibration trip is settled before the lid closes. Counting the load, cutting the pads, torquing diagonally and re-reading the level keep numbers stable over 380 km. Holding those conditions is the job of a testing equipment protective 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.