Is a QR code required for Case ID and Traceability?

Answer: No. Ten digits with a readable row also work, just slower to key in. The code earns its place at 0.2 to 1.5 m without focusing during a stock count.

How soon must a label go on after treatment?

Answer: Within 4 h, and never past 24 h. After that the surface falls back toward 33 mN/m and the bond becomes a gamble.

Answer: Side wall. The lid carries the stack load and the most rubbing; the flat area near the handle is the steadiest spot, provided it sits 8 mm clear of the seal.

PET label or aluminium plate?

Answer: Count rework first. Above 20 percent a year PET peels off cleanly; below it, aluminium buys 8 years at the cost of holes.

What if the code wears off?

Answer: Apply a fresh label with the same code at least 20 mm below the old one and leave the old label in place as a reference. Log both positions.

Case ID and Traceability: QR That Stays On

Quick answer: A Case ID and Traceability scheme fails at the label rather than the code, so treat PP to 38 mN/m and keep a 0.3 mm module clear of the seal.

Ten Digits Before Any Label
Getting It to Stick: 30 to 38 mN/m
Making It Scan: The 0.3 mm Module
Where Not to Put It
Rework, Residue, Peel Rate
FAQ

1. Ten Digits Before Any Label

Ten digits carry the whole Case ID and Traceability scheme: category 2, year 2, serial 6. Category separates box types, year keeps life-cycle sorting possible, and 6 digits hold a million units without a repeat.

Short codes survive being read by eye. When a scanner dies or half a label wears off, 6 serial digits can still be keyed in and matched against the record. A long random string fails completely once one corner is gone.

Keep the letters I and O out of the category positions; they get confused with 1 and 0 at reading distance. A digit-only alphabet lifts the hit rate on manual entry.

One code belongs to one case for life. New lid, new latch seat, same code. It is retired only when the case is scrapped, and never reissued.

2. Getting It to Stick: 30 to 38 mN/m

PP and PE sit at 30 to 31 mN/m, low enough that ordinary pressure-sensitive adhesive only makes point contact. It holds on day one and peels within 3 months. Roughly 80 percent of label failures begin here.

Case ID and Traceability label position check on a closed black case from above, red latches hooked over the front rim, plain white backdrop

The target is 38 mN/m or better. Flame, corona and plasma all reach it, and plasma is the steadiest, applied within 4 h of bonding because the surface drifts back toward 33 mN/m inside 24 h.

A dyne pen settles whether treatment worked. Grade 38 fluid that holds its edge for 2 s passes; fluid that pulls into beads is one grade short. Ten seconds here beats a batch of rework later.

Wipe with ethanol before bonding to clear dust and mould release. Release agent is the quiet failure: invisible, and the adhesive ends up gripping it instead of the polymer.

Thin sections need care. Under 2 mm a flame pass overheats the surface until it glosses, and adhesive grips worse; 2 plasma passes spread the effect instead.

Method	Outdoor life	Reading distance	Rework
PET label, 0.1 mm	3 to 5 years	0.2 to 1.5 m	Peels off whole, residue manageable
Aluminium plate, 0.5 mm	Over 8 years	0.3 to 2 m	Drilled or riveted, leaves holes
Laser marking	Life of the case	0.2 to 1 m	Permanent, can only be covered

3. Making It Scan: The 0.3 mm Module

Scanability is set by module size in millimetres, not by image resolution. A 0.3 mm module is the practical floor for handheld readers at 0.2 to 1.5 m; go smaller and a phone may still read while an industrial scanner starts missing.

Code width is module count times 0.3 mm. A 25-module symbol is about 7.5 mm square, and a quiet zone of 4 modules on each side brings the block near 10 mm.

The quiet zone has to stay blank. Print, rivets or a rib shadow inside 4 modules cut working distance from 1.5 m to under 0.5 m.

Print resolution has to match. At 300 dpi a dot is about 0.085 mm, so a 0.3 mm module gets 3.5 dots and its edges go ragged; run 600 dpi or widen the module to 0.4 mm.

Application runs 25 s: clean 8 s, place 6 s, roll 5 s, verify 6 s. Two passes with a 2 kg roller push trapped air out, and trapped air is where peeling starts.

4. Where Not to Put It

Placement decides whether adhesive migrates. The expensive lesson is a label set beside the seal: tackifier creeps along the wall at 40 °C, and anything inside 8 mm eventually contaminates the seal, pushing leak-down over the limit while the outside still looks clean.

Case ID and Traceability rework view of an empty black case with the lid raised, red latches standing up, hinge knuckles along the rim

Four hard lines: 8 mm from the seal land, 20 mm from the case edge, clear of latch and hinge seats, clear of radii and gate marks. On a radius under 20 mm the corners lift within a season. Near a gate mark the surface carries a 0.05 mm bump, the adhesive never wets it, and that dry patch becomes an air path.

Zone	Reason	Minimum gap
Seal land	Tackifier migration	8 mm
Case edge	Drop stress, corner lift	20 mm
Latch and hinge seats	Flex under load, shear	15 mm
Radius	Curved surface springs back	20 mm onto flat
Gate mark	Bump keeps adhesive from wetting	10 mm

Centre the label a third of case height above the base, 20 mm from the front face; that misses the 4 corners that land first in a drop.

5. Rework, Residue, Peel Rate

Peeling for rework leaves residue. Above 0.2 mm it has to be scraped off and wiped 2 times with IPA. Bonding a new label over old adhesive is the common mistake: shear strength halves and it will not survive a summer.

Aluminium plates in a Case ID and Traceability system need holes. A hole closer than 10 mm to the edge weakens the corner, and rivets should stay at 3 mm or under, sealed on the back.

The annual peel rate target is under 1 percent: labels replaced divided by cases in service. Past 1 percent, check treatment first, then adhesive thickness at 0.05 to 0.08 mm, thin enough to fail and thick enough to creep.

Take scrapped cases out of the denominator. Leaving retired units in dilutes the rate below 0.3 percent and hides the cases actually losing labels.

A re-lidded case keeps its old code. If a new label is unavoidable it repeats the code, the old one is photographed and destroyed, so two cases never share a code.

Conclusion

Case ID and Traceability usually fails on physics rather than on software: surface energy short of 38 mN/m, a label inside 8 mm of the seal, or a module under 0.3 mm. Any one of those and the label comes off inside 3 to 5 years, which is exactly when the record matters most. Ten digits, a 25 s application, adhesive of 0.05 to 0.08 mm and a peel rate under 1 percent make it something a line can hold.

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.