Machine Design #85: Standard Part Names — Name It So It Can Be Found, Bought, and Serviced
Standard part naming 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
- Part function and naming rule: record value, source, method, owner, and pass/fail evidence.
- Unique identifier, language, and abbreviation: record value, source, method, owner, and pass/fail evidence.
- Drawing, BOM, ERP, and supplier consistency: record value, source, method, owner, and pass/fail evidence.
- Revision and change history: record value, source, method, owner, and pass/fail evidence.
- Search and replacement evidence: record value, source, method, owner, and pass/fail evidence.
- Owner and review interval: 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 |
The structure of a name that works
A part name is not a label for fun — it is a search key in the bill of materials, in the stores and in the machine file five years later. A workable structure has two parts:
[Function noun] + [modifier: position, the thing acted on, or a distinguishing feature]
| Full name | Function noun | Modifier |
|---|
| Base plate, pump | Base plate | pump |
| Guide shaft, upper | Guide shaft | upper |
| Stopper, infeed blank | Stopper | infeed blank |
| Cover, coupling | Cover | coupling |
Putting the function noun first allows grouped searching: typing "base plate" returns every base plate in the machine. Reversed ("Pump base plate") the list sorts by the object and the grouping is lost.
Bad names and better names
| Bad name | The problem | Better |
|---|
| "The fish", "rabbit ears" | Internal nickname; newcomers and suppliers do not understand it | "Eccentric locating stop" |
| "L-shaped plate" | Describes the shape, says nothing about the function | "Motor support plate" |
| "Plate 100x50 SS400" | Stuffs size and material into the name | "Clamp plate" — size and material have their own fields |
| "Part 3" | Carries no information | A name reflecting the real function |
| "New base plate" | "New" loses meaning at the very next revision | Distinguish by revision or part number |
| "Support Bracket ASSY-2" | Mixes languages and private abbreviations | One consistent language and vocabulary |
Four things that do not belong in a name
- Dimensions — there is a dimension field and a drawing; putting them in the name means every size
change forces a name change, dragging the bill of materials and the purchase history with it.
- Material — there is a material field; same reason.
- Drawing number or part number — they have their own fields, and repeating them creates a place to
disagree.
- Temporary status — "new", "reworked", "temporary" all lose meaning within months.
Why this costs real money
Casual naming breaks four things, and all four cost money: finding a part in an old machine file, buying the right one when it has to be replaced, reusing the design on the next machine, and stocking spares. A part called "the fish" can only be found by the person who named it — and that is precisely the risk.
A quick check before fixing a name: give the parts list to someone outside the design and ask them to guess what each part does. Wherever they guess wrong, the name is not yet usable.
Significant and non-significant part numbers: pick one, do not mix
The part name is for people to understand; the part number is for the computer and the stores. There are two philosophies and they do not blend.
| Significant number | Non-significant number |
|---|
| Example | MD-AL-0125-A (group, material, sequence, revision) | 100234 |
| Advantage | Reading the number tells you which group the part belongs to | It never has to change when an attribute changes |
| Drawback | Change the material and the number lies; the scheme runs out of room as a group grows | You must query the system to know what it is |
| Suits | Small operations, few parts, few changes | Operations with a management system and many parts |
The practical trap of a significant number: an aluminium part carries AL in its number and is later changed to steel. Keep the number and it lies; change the number and you lose the purchase history and every drawing that referenced it. This is why larger systems drift toward non-significant numbers with the attributes held in the database.
More important than which style you pick: pick one and stay consistent. A half-significant scheme cannot be searched by either method.
Variants: when to share a number and when not
| Situation | Handling |
|---|
| Same geometry, different paint colour with no effect on assembly | May share a base number with a colour suffix, if the system supports it |
| Same geometry, different material | Different number — not interchangeable in mechanical properties |
| Left-hand and right-hand mirror parts | Different number — two parts, even on one drawing |
| Different lengths within one family | Different numbers, and if there are many, use a variant table on one drawing |
| A tolerance change where the old part still fits | Same number, raise the revision |
The compact rule is the same old question: are these two interchangeable? Answer that and the numbering decision follows, without arguing about conventions.
Variant tables: one drawing, several numbers
For a family differing only in a few dimensions — shafts of one diameter in several lengths, plates of one profile in several thicknesses — use one drawing with a variant table rather than several near-identical drawings.
Three things a variant table must have:
- The varying dimensions given as letters on the view (L, t, D), with the values in the table.
- Each table row is its own part number, not a note.
- Unchanging dimensions stay as numbers on the view, out of the table, so the table stays compact.
This cuts the number of drawings to maintain and, more importantly, means a change common to the whole family is made in one place.
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 standard part naming, evidence that identification and function remain reliable is the MINATA standard.
Frequently asked questions
Name by function or by shape?
By function. "L-shaped plate" describes the shape but says nothing about what it does, and one machine may contain five different L-shaped plates. "Motor support plate" can be searched, purchased and understood.
Should the size go into the part name?
No. Size and material already have their own fields on the drawing and in the bill of materials. Putting them in the name means every size change forces a name change, dragging along the bill of materials, the purchase history and the files of machines already delivered.
What about a machine that has used internal nicknames for years?
Keep the nicknames in conversation but use standard names in the records. If a bridge is needed, put the nickname in the notes field of the bill of materials during the transition — do not let it become the official name on the drawing.
Should names be in the local language or in English?
Use one language consistently across the whole machine, and follow the customer's requirement if there is one. More important than the language is consistency: the same kind of part must always take the same function noun, not "support plate" one time and "mounting plate" the next for the same thing.
Frequently asked questions, continued
Significant or non-significant part numbers?
It depends on scale, but what matters more is picking one and staying consistent. Significant numbers read well but lie once an attribute changes; non-significant numbers need a lookup but never go wrong. A half-significant scheme cannot be searched by either method.
Does a material change require a new number?
Yes, if the old and new parts are not interchangeable in their mechanical properties. That is the deciding question for every variant case, rather than a debate about numbering conventions.
May left-hand and right-hand parts share one number?
No. They are two different parts even if they share a drawing. Sharing a number leaves the stores unable to tell them apart and the assembler will pick the wrong one.
When is a variant table better than several drawings?
When the parts differ only in a few dimensions and are identical in everything else. One drawing with a variant table reduces the drawings to maintain, and a change common to the family is made in one place.
Does a variant table replace individual part numbers?
No. Each row of the table has to be its own part number. A variant table saves drawings, not numbers — the stores and purchasing still work item by item.
A quick table for the shop floor
Naming gets easier when the situation, the wording and the purpose are lined up:
| Situation | How to word or control it | Purpose |
|---|
| Functional name | State the part plus its role | e.g. sensor mounting plate |
| Distinguishing attribute | Add left/right, upper/lower when needed | Do not rely on the code alone |
| Purchasing name | Match the supplier's designation | Fast to find and replace |
A worked case
Names like "Plate A" and "Plate B" are easy at design time but mean nothing during maintenance. "Left sensor mounting plate" lets stores, the shop and engineering recognise the same part, while the drawing number stays the one unique identifier.
Conclusion
Standard Part Names 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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