Assembly-driven Execution
Assembly-driven execution describes a fundamental principle of engineering execution:
engineering progresses through assemblies and sub-assemblies, not through abstract task completion.
In engineering-driven projects, work becomes executable when parts of the product structure stabilise.
Assemblies therefore act as the primary carriers of execution.
Assemblies as execution carriers
An assembly represents a coherent portion of the product that must become executable as a whole.
Engineering execution unfolds as:
- assemblies gain definition,
- dependencies converge,
- and readiness accumulates structurally.
Progress is therefore not evenly distributed across tasks.
It concentrates where assemblies move from conceptual definition toward executable state.
An assembly is treated here as an execution reference, not merely as a bill-of-materials node or drawing container.
Why task-based views obscure execution reality
Task-based planning abstracts engineering work away from product structure.
As a result:
- execution progress appears fragmented,
- dependencies are hidden inside schedules,
- and readiness is inferred indirectly.
Task completion may advance while assemblies remain structurally unresolved.
Assembly-driven execution reverses this perspective by observing execution where readiness actually forms.
Engineering execution advances when assemblies become executable —
not when tasks are marked complete.
Readiness accumulation at assembly level
Readiness is not an attribute of individual tasks.
It emerges when:
- required definition is available,
- dependencies affecting the assembly are resolved,
- and execution constraints are structurally satisfied.
Assemblies therefore serve as natural aggregation points for:
- readiness,
- dependency resolution,
- and execution risk.
Structural visibility of dependencies
Dependencies converge structurally at assembly boundaries.
When execution is observed at assembly level:
- unresolved interfaces become visible,
- cross-disciplinary dependencies surface naturally,
- and coordination requirements can be discussed without relying on task abstractions.
This structural visibility is largely inaccessible in task-centric execution models.
Relation to Product Flow
Product Flow applies the principle of assembly-driven execution by modelling execution progress directly on assemblies and sub-assemblies.
The system treats assemblies as execution carriers through which:
- readiness states evolve,
- dependencies are resolved,
- and execution risk becomes observable.
Assembly-driven execution is therefore a foundational principle underlying Product Flow as an Engineering Execution System.
Relation to other execution principles
Assembly-driven execution forms the structural basis for other execution principles:
- BOM-based planning builds on assembly structure as execution reference.
- Phase-based engineering execution describes how assemblies transition through readiness states.
- Visibility and risk emerge from observing execution at assembly level.