Industry guide
QR codes for manufacturing
Manufacturing QR codes are usually direct part marks on metal or plastic, where contrast comes from surface texture rather than ink. Use error correction H, modules of 0.5 mm or more, and grade marks against ISO/IEC 29158 rather than eyeballing them.
Direct part marking is a different discipline
There is no ink. A laser, dot peen or chemical etch changes the surface, and the decoder sees the difference between a diffuse marked area and a specular unmarked one. That difference depends on the lighting angle, which is why a mark that reads on the bench fails on the line.
| Method | Contrast quality | Notes |
|---|---|---|
| Laser annealing (steel) | Best | Dark oxide, genuine luminance difference |
| Chemical etch | Good | Consistent, needs masking |
| Dot peen | Fair | Relies on shadow; needs dome lighting |
| Deep engraving | Poor | Shadow only, highly angle-dependent |
Specification
- Modules 0.5 mm or larger.
- Error correction H — oil, swarf and handling damage are routine.
- Dark mark on a light substrate, not inverted.
- Bead-blast or brush the surrounding area so unmarked modules are diffuse, not mirror.
Grade the mark, do not eyeball it
ISO/IEC 29158 (AIM DPM) grades marks on cell contrast, modulation, axial non-uniformity and reflectance margin. Ask your marking supplier for a graded sample under the illumination your line actually uses. A mark that passes on their bench under dome lighting may fail under your bar lights.
Payload
A serial number, not a URL. Short, offline-readable, and resolved by your MES. Uppercase alphanumeric keeps the encoder in the cheaper mode.
Micro QR and rMQR
For small components, Micro QR fits in 11–17 modules. For long thin surfaces — cables, pipes, vials — rMQR is rectangular. Both are read by industrial imagers and largely not by phones, so confirm your reading hardware first.