Article 18 of the Machinery Regulation 2023/1230: the substantial modification that turns anyone into a "manufacturer"

Direct answer: Article 18 of Regulation (EU) 2023/1230 establishes that any natural or legal person who carries out a substantial modification of a machine or related product — even one that has been in service for years — takes on the legal obligations of a manufacturer under Article 10, including the responsibility to declare conformity and apply the corresponding conformity assessment procedure. This affects maintenance workshops, industrial integrators, retrofitting companies and even professional users who rework equipment on their own account. Only the non-professional user who modifies their own machine for personal use is excluded. In this article we explain exactly what a "substantial modification" is, how it differs from Article 17, and what legal risk is assumed by whoever intervenes on third-party machinery.

Regulation 2023/1230, which replaces Directive 2006/42/EC and applies in full from 20 January 2027, incorporates Article 18 as a response to an increasingly common industrial reality: retrofitting, the modernisation of production lines, and the reworking of used machinery. Before this framework, legal liability in these cases generated constant interpretative doubts; the new Regulation codifies a clear criterion and links it directly to risk assessment.

Who can become a "manufacturer" by modifying a machine?

Unlike Article 17 — limited to importers and distributors in the context of placing products on the market, which we analyse in detail in a dedicated article in this series — Article 18 has a much broader scope: it applies to "a natural or legal person" with no restriction on their role in the supply chain. In industrial practice, this includes:

• Maintenance and repair workshops that replace critical components with specifications different from the original ones.
• Retrofitting companies that upgrade old production lines with new control systems, sensors or automation.
• System integrators that combine existing machines into new functional configurations.
• Professional users (companies) that modify machinery from their own industrial fleet to adapt it to a new production process.
• Machinery rental companies that adapt equipment between successive customers with different technical needs.

Article 18 itself expressly excludes only one case: "a non-professional user who carries out a substantial modification of their machinery or related product, for their own use, shall not be considered a manufacturer [...] and shall not be subject to the manufacturer's obligations set out in Article 10." This exception is narrow: it only protects the individual who works on their own equipment for personal use, not any company or self-employed professional acting in the course of their activity.

How is it determined whether a modification is "substantial"?

Article 18 expressly refers to the risk assessment as the instrument that "demonstrates" whether a modification is substantial. There is no closed list within the article itself, but the criterion combines two elements: the appearance of a new risk not covered by the original assessment, or the increase of an existing risk to a level not covered by the previous safety measures. As we explain in our analysis of the risk assessment methodology (Art. 12), this process must be formally documented every time an intervention is carried out on a machine in service.

In industrial audit practice, the interventions most frequently classified as substantial modifications include:

• Increasing the speed, power, load capacity or operating range of the machine beyond the original design parameters.
• Modifying or replacing the control system, PLC or software that manages safety functions.
• Changing the intended use of the machine to an application different from the one that prompted the original risk assessment.
• Removing, disabling or modifying guards, interlocks or emergency stop devices.
• Integrating the machine into a new production line or cell that alters the human-machine interactions originally envisaged.

By contrast, preventive maintenance tasks, the replacement of parts with identical spares or ones approved by the original manufacturer, or repairs that restore the machine to its original condition and performance, do not in themselves constitute a substantial modification.

Article 17 vs. Article 18: two different routes to manufacturer status

What obligations does whoever carries out a substantial modification assume?

Article 18 expressly refers to Article 10 of the Regulation, but limits its scope: the obligations are limited to "that machine or related product" or, if the modification only affects a component within an assembly of machinery, to "that affected machine or related product, as demonstrated by the risk assessment". It is not necessary to re-certify the entire assembly if the risk assessment precisely delimits the scope of the impact.

How IgeraIndustria resolves the classification of a modification

Frequently asked questions about Article 18

Does a repair workshop become a manufacturer for any repair?

No. Repairs that restore the machine to its original condition and performance, using identical spares or equivalent approved parts, are not substantial modifications. Article 18 is only triggered when the intervention creates a new risk or increases an existing one beyond what is covered by the original risk assessment, which must be analysed on a case-by-case basis.

Is a company that retrofits its own machinery for internal use exempt?

No. The exception in Article 18 is expressly limited to the "non-professional user" who modifies their own machine "for their own use". A company, even if it modifies machinery exclusively for its own internal process without placing it on the market, acts as a professional user and fully assumes the obligations of Article 10 over the modified machine.

What happens if several companies intervene successively on the same machine?

Each natural or legal person who carries out an independent substantial modification assumes the manufacturer's obligations with regard to their own intervention, to the extent that the risk assessment demonstrates the scope of that specific modification. It is advisable for each intervening party to precisely document the state of the machine before and after their action, in order to delimit responsibilities in relation to earlier or later interventions by third parties.

Is it mandatory to engage a notified body to validate the modification?

It depends on the applicable conformity assessment procedure, determined by Article 25 depending on whether the modified machine is listed in Annex I, Part A or B. If it is listed in Part A, the involvement of a notified body will generally be necessary; if it is not listed in Annex I or is in Part B with fully applied harmonised standards, internal production control (module A) may be sufficient.

Does the original manufacturer lose all responsibility after a substantial modification by a third party?

With regard to the elements of the machine that were not altered and that conform to the original design and risk assessment, the original manufacturer retains its previous regulatory responsibility. The new responsibility of the intervening party under Article 18 is limited to the elements affected by the modification, as demonstrated by the updated risk assessment.

How does Article 18 relate to machines that are already outside the original manufacturer's warranty?

The expiry of the commercial warranty is irrelevant for Article 18: the regulatory obligation is triggered by the technical fact of the substantial modification, not by the contractual warranty status. A machine with 15 years of service and no warranty in force remains subject to the same analysis if an intervention is carried out that substantially alters its risks.

Sources: Regulation (EU) 2023/1230 of the European Parliament and of the Council of 14 June 2023 on machinery (OJ L 165, 29.6.2023), Articles 10, 12, 17, 18, 21 and 25. This article is for informational purposes only and does not constitute legal or engineering advice.