Engineer-to-Order (ETO)
Engineer-to-Order projects are characterised by products that are defined specifically for each order.
Engineering is not a preparatory phase.
It is the core execution activity that shapes feasibility, timing, and downstream stability throughout the project lifecycle.
Execution characteristics of ETO projects
In Engineer-to-Order environments:
- product definition evolves continuously,
- engineering work overlaps with procurement and manufacturing,
- and execution readiness changes throughout the project.
As a result, execution cannot be treated as a fixed outcome of planning.
It must be observed dynamically as definition and dependencies evolve.
In ETO projects, engineering execution determines when production can realistically proceed — not the other way around.
Why planning assumptions break down
ETO projects rely on early planning assumptions in order to initiate procurement and production.
However:
- key interfaces may remain unresolved,
- assemblies stabilise at different rates,
- and changes propagate unevenly across the product structure.
This leads to situations where:
- plans remain formally valid,
- but execution readiness diverges structurally.
Traditional systems capture the plan.
They do not capture the evolving executability of the engineered product.
In Engineer-to-Order projects, execution risk emerges while plans still appear coherent.
Structural nature of execution risk in ETO
Execution risk in ETO projects is not primarily driven by schedule deviation.
It accumulates structurally when:
- readiness is assumed at assembly level,
- dependencies remain implicit,
- or workload concentrates around unstable parts of the product structure.
Because engineering execution continues throughout the project, such risk must be recognised before it manifests as production disruption.
Role of Engineering Execution Systems
Engineering Execution Systems address the structural execution challenges of ETO projects by making execution explicit.
They observe:
- readiness progression across assemblies,
- dependency resolution over time,
- and execution stability under evolving definition.
This allows ETO execution to be discussed in terms of structural readiness, rather than task completion or milestone achievement.
Relation to execution principles
ETO projects exhibit all execution principles in concentrated form:
- Assembly-driven execution
Execution stability depends on how assemblies converge structurally. - BOM-based planning
Product structure defines how changes propagate and where execution blocks emerge. - Phase-based engineering execution
Assemblies progress through readiness phases at different speeds. - Visibility and risk
Risk accumulates where assumed readiness diverges from structural reality.
Relation to Product Flow
Product Flow applies Engineering Execution principles to Engineer-to-Order environments as an Engineering Execution System.
The system does not constrain ETO processes.
It makes execution readiness, dependency convergence, and structural risk observable throughout the project lifecycle.
This visibility supports informed decision-making in contexts where definition and execution evolve simultaneously.