Q. Why are partly completed machines treated differently in the #MachineryDirective?

A. Partly completed machines are the only category of machine to which all the obligations under the directive do not apply. That is because it may not be possible for a "partly completed machine” to fully comply until it is incorporated into the end machine. Consequently there is a newly defined specific procedure for "partly completed machines" requiring that:

the assembly instructions for partly completed machinery must contain a description of the conditions which must be met with a view to correct incorporation in the final machinery so as not to compromise safety and health.
The declaration of incorporation must include:

a sentence declaring which essential requirements of this Directive are applied and fulfilled...and, where appropriate, a sentence declaring the conformity of the partly completed machine with other relevant Directives.
a statement that the partly completed machinery must not be put into service until the final machinery into which it is to be incorporated has been declared in conformity with the provisions of this Directive, where appropriate.

Manufacturers of partly completed machines will need to implement the prescribed procedures. The objective is to provide security to machinery builders and users in relation to the obligations on manufacturers of partly built machines, while providing clarity on the safe integration of such products in machines or assemblies of machines.