Assembly Process Planning is a very important task in the development of a new industrial product. If not done properly, it can lead to extremely high added costs, resulting from the impossibility to integrate components according to the prescribed assembly procedure. Typical problems are: insufficient room for moving a component to its intended position; screws not reachable with the prescribed tool; not enough visibility for the operator to ensure the quality of the assembly; etc.

The same considerations hold for maintenance procedures, with even more acuteness: in order to reduce maintenance costs, the number of components which the operator needs to disassemble and reassemble should be minimized. As a consequence, space tends to be restricted and overcrowded by other pieces of equipement, limiting the access paths for the component to be changed as well as for the tools.

Throughout the product development process, the assembly or maintenance procedures need to be verified for coherence with the current state of design of the product. The verification can be done with real prototypes or with virtual models. But in the early phases, no physical parts exist which can be manipulated to validate assembly tasks, only the virtual model can be used.