What Is Partly Completed Machinery?

A question we often hear in conversations with machinery manufacturers: "This unit we manufacture can't be sold on its own — it's integrated into another line; can we affix a CE marking to it?" The answer to this question lies in the definition of one of the most misunderstood concepts in the Machinery Directive: "partly completed machinery." In this article we cover in detail what partly completed machinery is, how it differs from complete machinery, which documents need to be prepared, and why CE marking works differently for this product group.

What Does the Concept of Partly Completed Machinery Mean?

Under the Machinery Directive framework, for a piece of equipment to be considered "machinery," it must be able to perform a specific function on its own, independently. However, much of industrial production proceeds with units that don't function on their own, but become functional once mounted on another machine, line or system. This is exactly where the concept of "partly completed machinery" comes in. A motor, a conveyor drive unit, a robot arm, a hydraulic power unit, or a module designed to be mounted onto a machine body — if it cannot perform a specific application on its own — is typically assessed in this category.

The distinguishing feature of partly completed machinery isn't that it's "incomplete," but that it "lacks independent functionality." In other words, the equipment can be mechanically and electrically highly advanced — even nearly finished — but if it can't do a job on its own without being integrated into a final machine, it falls into the partly completed machinery class under the legislation. Getting this distinction right directly determines which documents need to be prepared and when, and by whom, the CE marking is affixed.

The Difference Between Complete Machinery and Partly Completed Machinery

Complete machinery is equipment that can perform a specific application on its own, operate independently, and be offered directly to the end user; it carries the CE marking and is placed on the market together with the EU Declaration of Conformity. Partly completed machinery lacks this independence; it only gains function as part of a whole once integrated into another machine or system. This is why the CE marking is not affixed to partly completed machinery; instead, a different document called the "Declaration of Incorporation" is issued, and the equipment is delivered together with assembly instructions that clearly state the essential requirements it does not meet.

The Concept of Quasi-Machinery

In international literature and engineering practice, the term "quasi-machinery" is also frequently used for partly completed machinery. These two concepts refer to the same reality in practice: equipment or a subsystem designed to be integrated into a final machine, with no independent function of its own. When a manufacturer sees the term "quasi-machinery," it should know this corresponds to the legislative definition of "partly completed machinery" — it is not a different certification regime.

Why Doesn't It Carry the CE Marking?

The CE marking is a declaration that a product meets all the essential requirements of the relevant EU legislation. By definition, partly completed machinery cannot meet these requirements on its own, because the final machine's safety performance depends on which machine the partly completed unit is integrated into, under what conditions, and with what additional safety measures. This is why the legislation prohibits affixing the CE marking to partly completed machinery, and instead requires the manufacturer to clearly declare which requirements the product does not meet and which conditions must be met for final integration. See our article What Is CE Certification? for more on the general logic of the CE marking.

What Is the Declaration of Incorporation?

The Declaration of Incorporation is a separate legal document, issued by the manufacturer of partly completed machinery, distinct from the EU Declaration of Conformity. In this document the manufacturer declares which essential health and safety requirements the equipment meets, which it does not, any harmonized standards applied, that the equipment must not be put into service until it has been incorporated into the final machinery, and that it is delivered as part of the assembly instructions. The Declaration of Incorporation is a critical document that needs to be added to the technical file of the party that will CE mark the final machine; if this document is missing, the final machine's conformity assessment also remains incomplete.

Typical Examples of Partly Completed Machinery

The most commonly encountered examples of partly completed machinery in practice are: electric motors and gearboxes that don't operate independently and are manufactured to be mounted on another line; conveyor drive units designed to be integrated into a production line; hydraulic power units manufactured to be included in another machine's hydraulic circuit; robot arms and manipulators to be integrated into a production cell; and cutting, drilling or machining modules manufactured to be fitted to a main machine. What these pieces of equipment have in common is that, however technically advanced, they cannot perform a specific manufacturing process on their own. It's also common for a manufacturer's product range to include both complete machinery and partly completed machinery, which is why each product model needs to be assessed separately, on its own.

The Special Situation of Partly Completed Machinery in Risk Assessment

The risk assessment of partly completed machinery is structurally different from that of complete machinery. For complete machinery, risk analysis is carried out to cover the product's final use scenario from start to finish. For partly completed machinery, the manufacturer can only assess the risks originating from its own equipment; since it isn't known which machine the equipment will be integrated into, under what environmental conditions, or with what additional safety devices, the risk assessment necessarily remains conditional and limited. Clearly documenting these limits is critical both for the manufacturer to correctly define its own area of responsibility, and for the final integrator to understand which additional risks remain its own to assess. For more on the general risk assessment methodology, the principles of EN ISO 12100 — the core reference standard in machinery safety — can be consulted.

What to Watch for in Import and Export

Partly completed machinery moving through cross-border supply chains increases the risk of missing documentation. A company importing partly completed machinery must make sure the declaration of incorporation and the assembly instructions genuinely arrive with the equipment and that their content is complete; without these documents, the final machine's conformity assessment cannot be completed. On the export side, companies manufacturing partly completed machinery translating the declaration of incorporation and assembly instructions into the buyer's language, or at least a mutually understood language, prevents delays and misunderstandings in the supply chain. This is particularly important for long supply chains (equipment manufactured in one country, integrated in another, and sold to a third), where every party at every stage needs to clarify its own boundary of responsibility.

Testing and Verification for Partly Completed Machinery

Although partly completed machinery doesn't carry the CE marking, that doesn't mean no verification is done at all. The manufacturer can test the risks originating from its own equipment (for example, electrical safety, moving-part risks, structural strength) within its own scope, and add these results to the technical construction file and the declaration of incorporation as supporting evidence. These preliminary tests greatly ease the final integrator's own conformity assessment, because the integrator doesn't need to verify the partly completed unit's core performance from scratch — it only needs to assess the additional risks arising from integration. However, the scope of these tests needs to be clearly stated in the assembly instructions; otherwise the integrator won't know which risks have already been assessed and which remain its own responsibility, and unnecessary repeat testing — or worse, untested gaps — can result.

Relevant Directives and Standards

The concept of partly completed machinery is defined directly in the Machinery Directive 2006/42/EC, and Annex II B of this directive sets out the content of the declaration of incorporation in detail. The directive is being replaced by Machinery Regulation (EU) 2023/1230, applicable progressively from 20 January 2027; the new regulation largely preserves the concept of partly completed machinery while also adding new requirements relating to digital format and cybersecurity elements. The core standard referenced in the design and risk assessment of partly completed machinery is EN ISO 12100, which defines general design principles and risk-reduction methodology for machinery. Depending on the equipment type, product-specific type C standards (for example, standards specific to certain machine families) should also be included in the assessment. See our guide Which Directives Apply to My Product? to clarify which legislation applies to your product.

Step by Step

1. Clarify whether the equipment is partly completed machinery or complete machinery, based on the independent-functionality criterion.
2. Determine which essential health and safety requirements relate to the equipment, which are met, and which are left to final integration.
3. Carry out risk analysis to the extent applicable, and document the risks that could arise after integration as well.
4. Prepare the technical construction file specific to partly completed machinery.
5. Write the assembly instructions, clearly stating the integration conditions, the requirements not met, and the risks to watch for.
6. Prepare the Declaration of Incorporation and have it signed by an authorized signatory.
7. Deliver the equipment, together with the assembly instructions and declaration of incorporation, without the CE marking, to the final integrator.
8. Make sure the final integrator includes these documents in its own technical file when carrying out its conformity assessment for its own machine.

Most Common Mistakes

• Mistakenly affixing the CE marking to partly completed machinery.
• Confusing the declaration of incorporation with the EU Declaration of Conformity, or using the same format.
• Not clearly stating the unmet essential requirements in the assembly instructions.
• Assuming the equipment "already counts as machinery" without assessing its independent-functionality status.
• Incompletely passing on relevant information from the technical construction file to the final integrator.
• Not noticing that the declaration of incorporation for imported partly completed machinery is missing or never arrived.
• Trying to operate partly completed machinery independently before integration is complete.

Frequently Asked Questions

The concept of partly completed machinery can be thought of as a special branch of the general CE certification process; determining whether a product is complete machinery or partly completed machinery is a critical scope decision that needs to be made at the very start of the process. See our article The CE Certification Process Step by Step to see where this decision fits within a standard CE process; there you'll find how this step connects with all the other stages of the process.

Conclusion

The concept of partly completed machinery is one that machine and equipment manufacturers, especially those working on complex production lines, encounter often but frequently manage incorrectly. Mistakenly affixing the CE marking to a piece of equipment is just as risky as preparing an incomplete or incorrect declaration of incorporation — both can create legal risk and lead to mismatches with the final integrator. Clarifying from the outset whether your equipment falls into this category lets you both correctly bound your own responsibility and ease the process for other parties in your supply chain.