A degree of confusion surrounds the question of CE marking assemblies of machinery under the Machinery Directive 2006/42/EC. To help clarify the situation, the HSE (Health and Safety Executive) has published a new page on its website entitled In situ manufacture or assembly of work equipment and plant. This contains plenty of useful information for machine builders, system integrators, line builders and end users. Without wishing to repeat the contents in their entirety, the following highlights some of the more important points relating to assemblies of machinery and the addition of new machinery to existing assemblies.
As the HSE web page explains, an assembly of machines must be CE marked as a whole when individual machines are linked in order to perform a common function, when those machines are interconnected so that an individual machine (or element) affects the operation of others such that the whole needs to be risk-assessed, and when there is a common control system for the constituent units. On the other hand, if the connected machines function independently, this is not considered to be an assembly of machines for the purpose of CE marking to the Machinery Directive.
The HSE says that a complete industrial plant comprising many individual machines, assemblies of machines and other equipment should be treated as separate sections, with any risks at the interfaces covered by installation instructions.
Assemblies of machines must be CE marked as a whole by the responsible 'manufacturer' - which might be the system integrator, line builder or end user, whether or not they have manufactured the constituent units. If the individual units are capable of operating independently then they should be CE marked and be accompanied by a Declaration of Conformity (DoC); if they are placed on the market as partly completed machinery (intended for incorporation within an assembly of machinery, for example), then they should not be CE marked but they should be accompanied by a Declaration of Incorporation (Dol) and assembly instructions.
According to the HSE, a 'manufacturer' who is creating an assembly of machines is not responsible for the design of the individual machines and partly completed machines, provided the 'manufacturer' has checked that the equipment came with a DoC or Dol and adequate instructions (covering installation, operation, maintenance, etc), is CE marked where appropriate, and is free from 'obvious' defects (the HSE gives the example of damaged or missing guards).
So far we have considered only new assemblies of machinery, but the HSE web page for In Situ Manufacture also addresses the question of assemblies comprising new and existing machinery - as might be the case when a line is being modified, upgraded or extended. Whether or not the whole assembly needs to be reassessed under the Machinery Directive will depend on ta number of factors, so the HSE directs readers to the European Commission's official Guide to the Machinery Directive 2006/42/EC. However, the HSE's new web page does state 'where a new machine is added to an assembly you do not have to re-asses those other machines in the assembly which are not affected in any way.' Having said that, bear in mind that employers have certain duties under the Provision and Use of Work Equipment Regulations (PUWER), which may have implications for older machinery whether or not it is being modified.