Machine Modifications and Upgrades – When Is a New Conformity Assessment Required?

Changes to machines—whether mechanical or functional—can affect their compliance with applicable regulations. In many cases, a new conformity assessment and updated CE marking are required. A professional evaluation of each modification minimizes legal and operational risks.

What Are Machine Modifications and Upgrades?

Machine modification (or upgrade) is any change that can affect the machine’s safety, intended use, or compliance. If the change alters the original risk profile or safety functions, it may require a new conformity assessment, an updated technical file, and a new EU Declaration of Conformity under Directive 2006/42/EC and Regulation (EU) 2023/1230.

Typical examples include: retrofit automation, control system changes (PLC/software), new guarding, speed/force changes, adding modules, integrating the machine into a new line, or converting the machine for a different product/use.

Repair vs. Modification — what is the difference?

• Repair/maintenance restores the machine to its original condition (same function, same safety level, no new hazards).
• Modification/upgrade changes structure, function, performance, or safety concept — and may create new hazards or invalidate the original risk assessment.

Process of Assessing Machine Modifications

The key question is: does the change affect safety or compliance? Each project starts with an impact analysis to determine whether the modification:

• alters the machine’s structure, control system, or operating parameters,
• affects safety-related parts of the control system (SRP/CS) or safety functions,
• changes the original risk assessment or risk reduction measures,
• introduces new hazards (mechanical, electrical, software, ergonomic, noise, emissions),
• changes intended use, operating mode, or foreseeable misuse,
• involves integration into a new production line or interlocking with other machinery.

If any answer is “yes” — what must be done?

• perform (or update) a risk assessment and risk reduction plan,
• verify compliance with applicable requirements and harmonised standards,
• update technical documentation (technical file),
• update user instructions and safety information,
• issue a new EU Declaration of Conformity if required by the scope of change,
• ensure CE marking remains valid (or apply a new CE marking if the legal responsibility changes).

Who Is Responsible After a Modification?

If a modification is “substantial,” the entity performing it may take on manufacturer-like obligations (especially when the modification changes safety functions, intended use, or overall risk level). In practice, this means responsibility for the updated conformity assessment, documentation, and declaration may shift to the modifier/integrator.

This is why the responsibility assessment (who becomes the “manufacturer” for compliance purposes) is a standard part of the analysis.

When Is a New Conformity Assessment Required?

A new or updated conformity assessment is typically necessary when the modification:

• changes the machine’s intended use or operating conditions,
• affects safety functions or safety-related control architecture,
• modifies speed, force, energy, performance limits, or cycle logic,
• adds/removes guards, interlocks, protective devices, or emergency functions,
• integrates the machine with other equipment into a system/line with new interactions,
• introduces new modules (robots, conveyors, presses, lifting systems) or new hazards,
• requires application of updated harmonised standards due to design changes.

Step-by-Step Checklist After a Machine Upgrade

• 1) Define the change (scope, drawings, software versions, performance parameters).
• 2) Impact analysis (safety functions, risk profile, interfaces, intended use).
• 3) Risk assessment update (identify hazards, evaluate risks, define measures).
• 4) Verify safety design (guards, interlocks, control system, stopping performance).
• 5) Testing & validation (functional tests + safety function verification).
• 6) Update documentation (technical file + instructions + maintenance).
• 7) Compliance decision (DoC update/new DoC; CE validity confirmed).

Which Documents Usually Need Updating?

• risk assessment and risk reduction measures,
• drawings and diagrams (mechanical/electrical/pneumatic/hydraulic),
• safety function specification and validation evidence,
• technical file index and applied standards list,
• operating instructions (incl. residual risks, warnings, training),
• maintenance and inspection instructions,
• spare parts / safety components list,
• EU Declaration of Conformity (if required by change scope/responsibility).

GCB’s Approach to Machine Modifications

GCB provides end-to-end support for machine upgrades to confirm CE validity, reduce legal risk, and document compliance. Our scope includes:

• impact analysis of design and functionality changes,
• verification of risk assessment and safety concept,
• technical testing and inspections (incl. safety function checks),
• mapping and applying relevant harmonised standards for the modified scope,
• preparation/update of technical documentation and declarations,
• support for integrators and production line projects,
• coordination with Notified Bodies where required.

Why Follow the Compliance Process?

Incorrect handling of a machine modification can invalidate CE compliance. This may result in:

• loss or invalidation of CE marking validity,
• administrative penalties and market surveillance actions,
• liability exposure in the event of incidents or accidents,
• shutdown or prohibition of machine operation,
• issues with insurance coverage and contractual claims.

Proper compliance procedures enable:

• alignment with current legal requirements and standards,
• higher operational safety and lower incident risk,
• improved performance without compliance gaps,
• reduced legal and commercial risk (audits, customers, insurers).

Common Mistakes After Machine Upgrades

• treating a functional change as “maintenance” and skipping risk assessment updates,
• changing PLC/software without validating safety-related control functions,
• integrating machines into a line without assessing new interfaces and hazards,
• updating guards/interlocks without documenting residual risks and instructions,
• not updating the applied standards list after design changes,
• missing evidence of testing/validation in the technical file.

GCB’s Services for Post-Modification Assessments

After a modification, GCB supports your conformity assessment by providing:

• change impact analysis (safety, intended use, risk profile),
• gap analysis vs. applicable requirements and standards,
• risk assessment review and update support,
• technical documentation preparation (technical file + instructions),
• certification process coordination and project management,
• support in communication with Notified Bodies (if required).