Substantial modification of machinery: when a new conformity assessment is needed

Because the theme is important

The problem is not just bureaucratic. An unrated modification may compromise safety, validity of documentation, responsibility of the employer and product compliance. The typical case is a CE marked machine that is integrated with new movements, new automation, new devices, new software logics or new operating modes not provided by the original manufacturer.

What is a substantial modification

The Regulation defines substantial modification of a physical or digital change, made after placing on the market or putting into service, not foreseen or planned by the manufacturer, which affects safety by creating a new danger or increasing an existing risk and requiring significant protection measures.

Physical and digital changes

The concept is not only about mechanical changes. Even a software modification can be substantial if it affects the safe behaviour of the machine. Typical examples are changes to command logic, speed, working zones, automatic modes, interfaces, remote access or functions that affect safety circuits.

The fact that a change is “only software” does not automatically make it irrelevant. If the change changes the risk conditions, it must be evaluated and documented with the same attention as a physical modification.

When changing becomes a manufacturer

According to the Regulation, the natural or legal person who makes a substantial modification is considered to be a manufacturer for the purposes of the Machinery Regulation or for the part of the machine concerned by the modification. This entails precise obligations: risk assessment, application of essential requirements, technical documentation, conformity assessment procedure and declaration under its own responsibility.

Practical examples

• addition of a robot or manipulator not provided in the original configuration;
• increase speed or force of an axis with impact on risks;
• changes in access to dangerous areas;
• replacement of the control system with new safety logic;
• remote access introduction that can affect safety functions;
• integration of multiple machines in a line with new dangerous interfaces.

On the contrary, maintenance, repair or replacement activities with equivalent components may not configure a substantial modification, provided they do not alter compliance with the applicable requirements and do not introduce new risks.

What to document before changing a machine

• Technical description of the machine before modification.
• Detailed description of the planned modification.
• Evaluation of new or modified hazards.
• Impact on guards, safety circuits, software, stability, instructions for use and procedures.
• Technical standards applicable to the change.
• Motivated decision: substantial or non-substantial modification.
• Any updates to technical file, instructions for use, declaration and marking. Reference

Waves method to evaluate a change

Waves Engineering applies a documentary and technical method: we analyze the machine, the modification, the risks introduced, the necessary protective measures and the impact on existing documentation. The goal is to provide the customer with a clear and defensible technical evaluation, avoiding both dangerous underestimations and unnecessary certifications.

The result can be a technical report of the classification of the modification, or a complete path of new CE assessment when the change is substantial.

FAQ

Is an improved safety change always substantial?

Not necessarily. If the change increases safety without introducing new hazards or altering compliance, it may not require a new CE marking. It must still be documented.

Can an electrical retrofit or software be substantial modification?

Yes, if it affects safety functions, it creates new hazards, increases existing risks or requires new significant protection measures.

Who is responsible for the modified machine?

If the change is substantial, the person who performs it can be considered manufacturer under the Machinery Regulation for the modified machine or the part affected by the change.