as-built

Core meaning

“As-built” commonly refers to the documented record of how a product, asset, or system was actually constructed or assembled, as opposed to how it was originally designed or planned.

In industrial and regulated manufacturing, an as-built typically captures:

– The exact components and materials used
– The configuration and options applied
– The manufacturing route or operations actually executed
– The revisions, waivers, and deviations that occurred
– The serial numbers and lot numbers for traceable items

The term is used for both:

– **As-built configuration**: The complete, factual configuration of a unit or asset at a point in time.
– **As-built documentation**: The drawings, models, records, and data sets that describe that configuration.

Use in manufacturing and operations

In manufacturing environments, an as-built is usually built up from execution data, including:

– Work orders and operation history
– Equipment and tooling used
– Inspection and test results
– Nonconformances and rework records
– Component genealogy (lot/serial traceability)

Systems such as MES, PLM, or ERP may each hold parts of the as-built, with integrations used to assemble a complete record for a specific serial number or asset.

As-built data is frequently used for:

– Unit-level traceability and genealogy
– Configuration control in complex products (e.g., aerospace, medical devices)
– Maintenance and service planning
– Investigations, recalls, and root cause analysis

Boundaries and exclusions

“As-built” in this context:

– **Includes**: The factual state of a product or system after it has been manufactured or installed.
– **Excludes**: Purely theoretical or intended states, such as:
– “As-designed” (what engineering specified)
– “As-planned” or “as-scheduled” (what operations planned to do)
– “As-maintained” (state after field modifications or service work, unless the term is explicitly extended to that lifecycle stage)

The as-built may be updated over time if the definition is extended to reflect post-delivery modifications, but in many organizations it is fixed at the point of release or shipment and later states are tracked separately.

Common confusion with related terms

– **As-designed vs. as-built**: As-designed refers to the engineering intent (CAD, BOM, specs). As-built is the factual result of manufacturing, including substitutions and deviations.
– **As-planned vs. as-built**: As-planned covers the intended process route and standard BOM. As-built reflects what actually happened and what was actually installed or assembled.
– **Digital twin**: A digital twin may incorporate as-built data, but the as-built itself is the record of reality, not necessarily a live, behaviorally accurate model.

In regulated industries, it is important not to treat planned or design data as an as-built record unless it has been verified and reconciled against execution data.

Site context: MES and complex assemblies

For complex assemblies such as aerospace structures, the MES often plays a central role in building the as-built record by:

– Capturing which components (by serial or lot) were installed on each unit
– Recording which operations and inspections were performed and by whom
– Linking nonconformance, rework, and concession records to specific units

In this context, the as-built configuration for each serial number is reconstructed from MES data and synchronized with PLM or ERP to maintain configuration control across the product lifecycle.