BOMBill of Materials

A complete BOM line carries: parent SKU / formulation ID, component item code, component description, quantity per parent unit, unit of measure (kg, L, ea, m), consumption type (issue / backflush / phantom), scrap / yield allowance, effectivity start and end dates, engineering / formula revision link, position / step / phase (which manufacturing step consumes it), and an indicator of whether the component is critical (CMA / fit-form-function) versus alternate-acceptable. In regulated manufacturing the BOM line also carries the link to the approved specification version, the QA-disposition policy (use-as-is vs full lot release required), and any potency / assay basis flag that drives recalculation at issue.

• Engineering BOM (EBOM) — the design view: what the product is, organised by assembly / sub-assembly tree as the engineer sees it. Often source-of-truth in PLM.
• Manufacturing BOM (MBOM) — the make view: the same product organised by how it is built, with phantom assemblies expanded, packaging and consumables added, scrap factors and yield assumptions baked in. Source-of-truth in MES/MRP.
• Planning BOM — the demand-planning view: a pseudo-parent with percentage-based components (model mix, option mix) for forecasting purposes. Not a buildable BOM.
• Phantom BOM — intermediates that are made and immediately consumed; not stocked, only modelled for accuracy.
• Costed BOM — the same MBOM with standard cost rolled up at every level; drives COGS and variance analysis.
• Reverse / where-used BOM — query, not a type: 'which parents use this component?', critical for impact assessment of a component change or recall.

In regulated industries the BOM is the formula. 21 CFR 211.186 requires a Master Production Record that lists the name and weight or measure of each active ingredient per dosage unit or per batch, the complete list of components including their identifying code, and the theoretical weight / measure at each stage of processing. 21 CFR 820.181 requires a Device Master Record that includes the device specifications, production process specifications, and quality assurance procedures — the BOM is the component side. 21 CFR 111.205 / 111.210 require a dietary-supplement Master Manufacturing Record with the same level of structured component data. EU GMP Chapter 4 §4.21 (Manufacturing Formula and Processing Instructions) and Annex 15 §6 on change control parallel the US framework. Every regulated BOM is versioned, change-controlled, approved by two distinct e-signatures (preparer + independent reviewer per 211.186 / 111.205), and immutable once approved — changes create v+1.

The BOM lives on the formula / item master and evolves through change control. The work order, by contrast, must execute against a frozen copy: at WO release the full BOM is copied into the WO record (in V5 this is `work_orders.mmr_snapshot`) so that subsequent formula changes do not retroactively alter the executed batch. The regulated principle (211.188(b)(1) for pharma, 820.184(c) for devices, 111.255 for supplements) is that the batch / device-history record must be an 'accurate reproduction' of the master at the time of manufacture — which is only possible if the BOM was pinned at release. Reports always render from the snapshot, never from the live BOM.

Each BOM line carries an effectivity start date and end date so that a planned change (new lubricant supplier, new packaging substrate, removed component) can be authored, approved and queued in advance, with the cut-over occurring at the right WO date or lot number. This is the engineering-change-order (ECO) link: the change control authorises the BOM revision; the BOM revision carries the dates that determine which WOs receive the old vs new component. Mature MES / ERP enforce this by lot number rather than date alone — 'use new lubricant from lot 47 onwards' is a deterministic rule that survives WO date slippage.

1. Engineering BOM used for execution without manufacturing-side expansion — phantom assemblies, packaging and consumables missing from the work-order pick list.
2. BOM revision implemented at the master but not change-controlled — a deviation never raised, the change just appeared.
3. WO references formula v3, but during execution someone edits formula to v4 and the in-flight WO inherits the change.
4. Component substitution allowed at the floor without a documented alternate-acceptable flag — wrong material consumed because both were 'sort of similar'.
5. Scrap / yield allowance built into the BOM is unrealistically tight, causing chronic MRP shortages and routine emergency POs.
6. Costed BOM not refreshed for 18+ months — standard cost still reflects the supplier that was replaced last year.
7. Where-used query slow / nonexistent — recall impact assessment takes days because the BOM relationships aren't indexed.

• Single formula master per product per industry-aware terminology (Formula / Recipe / Assembly / Kit) — the BOM is its structured component table.
• Immutable approved versions — changes create v+1; the approve path requires two distinct e-signatures (preparer + reviewer) per 211.186 / 111.205 / 820.181.
• Effectivity dating and lot-cut-over rules per line — planned changes queued in advance, deterministic cut-over.
• On WO release, full BOM copied into `work_orders.mmr_snapshot` jsonb — reports and BMR/DHR/BPR always render from the snapshot, not the live formula.
• Where-used query indexed — recall and impact-assessment work begins with a one-second query, not an overnight extract.
• Substitution requires a documented alternate-acceptable flag on the BOM line; at issue the substitute is e-signed against the deviation that authorises it.
• Standard-cost roll-up on the costed BOM refreshes nightly from current material costs; variance shows where standards have drifted from actuals.
• Industry-aware language: discrete tenants see 'Assembly / Sub-assembly / Part'; process tenants see 'Formula / Recipe / Ingredient'; never hard-coded — read from the labels dictionary.