This paper describes a global interactive scheme including fast motion planning and real time guiding force for 3D CAD part assembly or disassembly tasks. For real time purpose, the motion planner is divided into different steps. First, a preliminary workspace discretization is done without time limitations at the beginning of the simulation. Then, using those computed data, a second part tries to find a collision free path in real time. Once the path is found, an haptic artificial force is applied constraining the user on the path. The user can then influence the planner by not following the path and automatically order a new path research. The performance of this haptic assistance is measured on a test simulation based on an ALSTOM power components assembly simulation.