My company is installing a new production line which comprises of 4  different machine processes. each one of the machines has its own CE/UKCA certification and DoC. My question is whether I need to arrange for a declaration of incorporation on the finished layout. The guidance states that a declaration of incorporation would be required for incomplete machines or those intended to be installed with other machines. In this case all the equipment we are putting together is able to opereate independantly. Any help would be greatly recieved?      

If the four independent machines are being externally controlled to act as a single operation i.e. automatic transfer between processes - raw materials provision / some form of processing / packing / palletising all linked by conveyors - then you would need to arrange a Declaration for the total site assembly.

This is required as none of your component suppliers would have knowledge or input as to how all the components relate and interact with one another - their DoC being solely for the product they have supplied.