Machine Design #88: Machine Labels — A Small Plate Carries the Equipment Lifecycle
Machine label must remain clear, manufacturable, searchable, inspectable, and maintainable when the boundary changes.
Function before naming
Write the function, input, expected result, failure symptom, acceptance limit, and measurement method before selecting a name, mark, material, or note. Assign an owner to every value.
Core checks
- Asset identity, model, serial, and revision: record value, source, method, owner, and pass/fail evidence.
- Rating, warning, and required user information: record value, source, method, owner, and pass/fail evidence.
- Location, material, attachment, and durability: record value, source, method, owner, and pass/fail evidence.
- Readable code and database link: record value, source, method, owner, and pass/fail evidence.
- Change, replacement, and inspection: record value, source, method, owner, and pass/fail evidence.
- End-of-life and record closure: record value, source, method, owner, and pass/fail evidence.
| Failure mode | Symptom | Verification |
|---|
| Ambiguous identity | Wrong part or record | Search and audit a real lot |
| Omitted interface | Purchase, assembly, or service error | Walk the real route |
| Documents out of sync | Correct name, wrong revision | Baseline every reference |
Labelling is a system, not a plate
Calling it "the machine label" makes people think only of the identification plate on the frame. In reality a machine carries several groups of labels, each serving a different person at a different moment.
| Label group | Who uses it and when | What happens if it is missing |
|---|
| Machine identity — name, model, serial number, year, manufacturer | Maintenance and spare-part purchasing, for the whole life | The configuration cannot be traced, wrong spares are bought |
| Supply data — voltage, phases, frequency, power, air pressure | The electrician at connection and at repair | Wrong supply connected, wrong protective device chosen |
| Warnings — hazardous voltage, hot surface, pinch point, laser | Anyone approaching the machine, at any time | A layer of safety information is lost |
| Operating instructions — direction of rotation, valve sequence, oil level, lubrication points | Operation and periodic maintenance | Wrong sequence followed, servicing missed |
| Service points — lifting points, isolation point, earthing point | Installation, relocation, repair | Lifting at the wrong point distorts the frame; no isolation point exists |
| Assembly and wire identification — cabinet numbers, motor numbers, sensor numbers, tube numbers | Fault finding and repair | Downtime stretches exactly when it is least affordable |
That last group is often treated as the panel builder's business, yet it is the group that decides downtime when something fails. The numbering has to agree between the schematic, the cabinet and the physical item.
Labels fail in three predictable ways
- Peeling and fading. A paper or inkjet label placed where there are solvents, oil, water or
sunlight loses its text within months. Choose the material and the fixing for the real environment at that position, not for the average environment of the plant.
- Being covered. A label applied where a guard, a cable tray or a cabinet will later hide it. The
label position has to be checked on the fully assembled model, not on the loose part.
- Being moved. An identification label stuck on a removable panel will one day be refitted to a
different machine. Identification labels belong on structure that does not come off.
For loose parts inside the machine, marking directly is more durable — choose the method and the position per Machine Design #89 — Part marking.
A label has to connect to records, otherwise it is only text
The main value of a serial number is that it opens a set of records: which revision of the drawings, which bill of materials, which software version, which parts have been replaced. For that, the serial number has to be recorded on the manufacturer's side together with the configuration state at the time of delivery — the way revision is managed is in Machine Design #107 — Drawing revision tables.
One small but important decision: do not engrave a software version or a drawing revision on a metal plate, because those change during the life of the machine and the plate does not. Put changing information on a separate replaceable label, or in the records retrieved by serial number.
Language and symbols
Labels serve the person at the machine, so the language follows the place of use, not the place of design. For warnings, a graphic symbol reads faster than text and does not depend on language; the text alongside states the consequence and the required action. A machine delivered to a plant with Japanese engineers often needs bilingual labels — the warning signs common in Japanese plants are covered in Technical Japanese #07.
The plate has to survive the machine's environment
A correct label that peels off after six months is as good as no label. Choose the plate material and the fixing method by the environment the machine lives in, not by what the shop happens to stock.
| Environment | Label to use | Avoid |
|---|
| Indoor, dry, low impact | UV-printed anodised aluminium | Laminated paper labels |
| Oil, solvents, frequent wipe-down | Laser-marked stainless, or etched anodised aluminium | Inkjet-printed labels |
| Outdoor, sunlight | Stainless steel, UV-stable polycarbonate | Ordinary plastic (fades, goes brittle) |
| Heavy vibration, high heat | Marked directly on the body, or riveted plate | Adhesive-stuck labels |
Three things decide how long a label lasts:
- How the characters are made: engraving or laser marking outlasts surface printing, because the
printed ink layer wears through first.
- How it is fixed: rivets or screws beat adhesive; adhesive only suits a flat, clean, oil-free face.
- Where it sits: put the plate where hands do not constantly brush it, where no fluid runs directly
over it, and where it stays readable after the machine is installed in the line.
Minimum data on a machine label
For a machine assembly, the plate should carry enough to look the unit up later without opening a file:
- Name/model and serial number — the serial is the key that links to the as-built record.
- Electrical ratings where relevant: voltage, current, frequency, power.
- IP protection rating if the machine sits in dust or damp.
- Year of manufacture and the name of the manufacturer.
A 2D code (DataMatrix/QR) marked alongside lets you scan straight to the record, but always keep the human-readable text as well: if the scanner fails, a person can still read the serial.
MINATA release checklist
- [ ] Function, identity, boundary, and failure symptom are written.
- [ ] Ownership, interface, and mistake-proofing are clear.
- [ ] Six topic checks have evidence and pass/fail limits.
- [ ] Manufacturing, purchasing, inspection, and maintenance were tried.
- [ ] Revision, supplier, database, and lifecycle records agree.
Good engineering is an explicit chain that survives manufacture, operation, maintenance, and change. For machine label, evidence that identification and function remain reliable is the MINATA standard.
Frequently asked questions
Where should the identification label go on a machine?
On structure that does not come off, in a position still visible after the machine is fully assembled and connected. Check that position on the complete assembly model, because many labels only become hidden once guards and cable trays are fitted.
Should the software version be engraved on a metal plate?
No. Anything that changes during the life of the machine belongs on a separate replaceable label or in records retrieved by serial number. A metal plate should carry only fixed information.
Why does a label lose its text within months?
Because the material was chosen for the average environment of the plant rather than the real environment at that position. Places with solvents, oil, high-pressure washdown or direct sunlight need a different material and fixing method.
Is numbering wires and assemblies the designer's job?
Yes, because the numbers have to agree between the schematic, the cabinet and the physical item. If each party numbers independently, fault-finding time grows exactly when nobody has time to spare.
Which language should labels use?
The language of the place of use. For warnings, use a graphic symbol as the fast-reading layer and text to state the consequence and the required action. For a machine delivered to a plant with foreign engineers, consider bilingual labels.
Frequently asked questions, continued
Is laser marking on stainless as durable as a riveted plate?
More durable over time: there is no separate plate to peel and no ink layer to wear. The drawback is that changing a number is hard, so mark only fixed data directly (serial, model); put changeable data on a secondary label.
Should I add a DataMatrix code or is a printed serial enough?
Add both. The DataMatrix scans quickly and avoids typing errors; when there is no scanner, or the code is scratched, the eye-readable serial is the fallback.
Is the year of manufacture mandatory?
For many export markets and under CE marking rules, the year and the manufacturer are mandatory on the machine. Even where they are not, the year helps establish the machine's age for depreciation and the maintenance schedule.
Conclusion
Machine Labels is not paperwork done to make a file look tidy. It is how intent becomes a result that can be manufactured, assembled and measured repeatedly. A good drawing does not need the designer standing beside it to explain it; the structure of the information has to do that work.
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