BOM

English

Ask any sustainability question about a physical product and you will find yourself asking three smaller ones: what is inside it, how much of each, and where did it come from. That is the BOM, exactly. This is why the work starts there — and why it is handled with care, because a BOM is among the most confidential things a company holds.

So the practice is not "share the BOM". The practice is: build the joins around it, work in structure and in aggregate, and let each function read only the field it needs. When the joins exist, deep-diving stops feeling like archaeology and starts feeling like reading a map.

The bones · already there

• Unique part identity + revision control — one part, one number, one state in time.
• Parent–child structure — indented levels that describe how a product is actually built.
• Quantity and unit of measure per level, with usage that rolls up.
• Approved vendor / manufacturer list linked to the part, not to a person's memory.
• Change history — every ECO/ECN says who changed what, when, and why.
• Lifecycle status — prototype, production, phase-out, obsolete.

Gaps we keep meeting

• Mass at homogeneous-material level — part weight exists; grams of copper, of ABS, of solder alloy usually do not.
• Substance composition to CAS level — declarations exist as documents (IEC 62474 / IPC-175x) but are rarely joined to the line.
• Recycled content % — and the split between post-consumer and pre-consumer, with evidence attached.
• Origin at site level — we often hold the legal entity, not the manufacturing site and its grid.
• Sub-tier visibility — Tier 1 answers; Tier 2, 3, n stay dark.
• Packaging as BOM items — the box, foam, tray and pallet are real mass and real emissions.
• Emission factor per part — no hook for a product carbon footprint value, its method, or its boundary.
• End-of-life attributes — fastener type, disassembly sequence, separability, recyclability.
• Provenance of the data itself — who declared it, on what date, valid until when.

The hand-offs

• Design intent — schematic, CAD, material selection. The first moment a gram of copper is decided.
• EBOM — engineering view: function, reference designators, revisions.
• MBOM — manufacturing view: routing, phantom assemblies, scrap, consumables, packaging.
• Sourcing & AVL — vendor, site, alternates, second sources.
• Supplier declaration — substance, mass, origin, carbon — usually a document, per request.
• Compliance & carbon systems — a separate database, often keyed differently.
• Report — the number that leaves the building.

Every hand-off is a place where fields quietly drop. Mapping is not adding a new system; it is restoring the joins between the ones we already run.

What the next five years will ask for

• A stable, cross-system part identity — the same part recognisable in PLM, ERP, compliance and carbon tools.
• Homogeneous material mass — the unit that recycling, restriction and carbon all secretly run on.
• Substance to CAS level with declaration source and date.
• Recycled content with type, %, and evidence reference.
• Product carbon footprint value + method (e.g. ISO 14067) + boundary + primary vs. secondary data flag.
• Manufacturing site + geography, because electricity is local.
• Data validity window — every value carries a date and an expiry, or it will be quoted forever.
• Repair & disassembly attributes — fasteners, tools, sequence, spare availability.
• A passport-ready identifier so a product can carry its own record.

Illustrative only · generic parts · invented numbers

Same line item. One is a classic BOM row. The other is the same row made answerable. Nothing here is taken from any real product or supplier.

From real practice

• Confidentiality is real. A BOM cannot be circulated. Work through structure, fields and aggregates — design the access, not the exception.
• One part, many identities. Internal number, supplier number, customs code, carbon-tool ID. Without a key, every analysis restarts.
• Suppliers answer per request, not per part. The same question returns in a new template every quarter.
• Unit-of-measure mismatch. EA vs. kg vs. metres — mass roll-ups quietly break.
• Phantom assemblies and alternates double-count or vanish mass depending on how you flatten the tree.
• Data ages faster than reports. A 2022 factor quoted in 2026 is a finding waiting to happen.
• Nobody owns the field. Engineering says sourcing, sourcing says quality, quality says sustainability.
• "We asked and got a PDF." A document is an answer. It is not yet data.

Nine questions ／ 九个问题

Not an audit. If one line makes you pause — if it names something you had never thought about — that pause is the value. Nothing is stored; this list lives only in your browser.

这不是稽核。如果某一行让你停顿一下，让你看见从没想过的事，那个停顿就是价值。勾选不会被储存，只存在你的浏览器里。