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The complexity of machine assemblies and upgrades

The complexity of machine assemblies and upgrades

Any substantial changes to machinery, such as upgrades, or interlinking with other equipment as part of an assembly, may make the existing CE Marking Declaration of Conformity invalid, and could necessitate a new conformity assessment, as Paul Taylor of TUV SUD Product Service explains.

Even though individual machines may comply with the Machinery Directive, when they become part of an assembly or production line, which links two or more machines, it is this entire assembly that is then considered to work as an integral whole and must therefore be CE marked as a new machine. Similarly, if modifications are carried out that alter the performance or function of a machine, or assembly of machines, this is considered to be creating an entirely new machine which warrants recertification.

If you are creating an assembly by interlinking a series of existing machines you are in effect creating something new. Therefore whoever is carrying out the work must ensure that the entire assembly complies with the Machinery Directive, regardless of the age of the machines.

The Guide to the Application of the Machinery Directive defines assemblies of machinery as “consisting of two or more machines or partly completed machines assembled together for a specific application. The definition of assemblies of machinery indicates that assemblies are arranged and controlled so that they function as an integral whole in order to achieve the same end.”

It also gives real-use examples of what constitutes an assembly: “a packaging machine and a labelling machine, or by several units assembled together, for example, in a production line.”

For a group of units of machinery or partly completed machinery to be considered as an assembly of machinery, the Machinery Directive Guide states that all of these criteria must be fulfilled:

  • The constituent units are assembled together in order to carry out a common function, for example, the production of a given product;
  • The constituent units are functionally linked in such a way that the operation of each unit directly affects the operation of other units or of the assembly as a whole, so that a risk assessment is necessary for the whole assembly;
  • The constituent units have a common control system.

However, according to the Guide, a group of machines that are connected to each other but where each machine functions independently of the others is not considered as an assembly of machinery in the above sense. Neither does the definition of a machine assembly extend to a complete industrial plant which consists of a number of production lines. Referring to such circumstances, the Guide states that: “Only if the plant forms a single integrated line is it subject to the Machinery Directive as an assembly.”

Under the Machinery Directive, the system integrator or end user that has created the machine assembly from separate units is responsible for ensuring that the assembly complies with the Directive’s essential health and safety requirements. This is most likely the case, as it is common practice for manufacturers of separate machines to place them on the market as complete machinery, which could operate independently, or as partly completed machinery that will then be assembled into a larger unit.

However, if the organisation buys the entire assembly from an original manufacturer, it must bear the CE marking and be accompanied by a Declaration of Conformity. If machines are placed on the market as partly completed machinery, they should not have the CE marking applied, but must instead be accompanied by a Declaration of Incorporation and the assembly instructions. It is then the machinery system integrator / end-user’s responsibility to ensure compliance and apply the CE marking process to the entire assembly.

If the constituent parts are functionally linked in such a way that each unit affects the operation of the others, a risk assessment of the whole assembly is necessary.

The risk assessment must cover the suitability of the separate units for the safe operation of the entire assembly, and potential hazards resulting from the interaction between them. It must also cover any hazards that are not covered by the Declaration of Conformity, the Declaration of Incorporation and the assembly instructions for the individual units. These three document types must also be included within the machine assembly’s technical file.

The machinery assembly must be designed and constructed in such a way that the stop controls, including the emergency stop devices, can stop not only the machinery itself but also all related equipment, if its continued operation may be dangerous. Where individual machines making up an installation are not linked together via a main control system, this would not be classed as an assembly of machines under the Machinery Directive.

The technical file must document any modifications that have been made to the separate units, when incorporating them into the assembly. Also, during its lifetime, one or more units of an existing assembly may be replaced by new ones, or new units added to an existing assembly. For such machinery in service, under regulation 10 of PUWER, the employer must ensure that the conformity and safety of the machinery is maintained throughout its working life.

When a machine assembly is first created, or later has substantial changes made, a full CE marking and Provision and Use of Work Equipment Regulations (PUWER) assessment must be completed before that machine can be returned to service. Creating a machine assembly can be a complex process, but guidelines from sources such as the Health and Safety Executive, as well as ensuring a thorough understanding of the Machinery Directive, should bring clarity.

In our experience, many machinery owners assume that if individual equipment within an assembly has the CE marking then no further action is required. However, CE marking must be done for the assembly as a whole, and it is an employer’s responsibility to ensure that new machinery assembly meets the requirements of both the Machinery Directive and the Provision and Use of Work Equipment Regulations 1998 (PUWER).

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