This paper presents an interactive constraint based system that simultaneously assist design and evaluation. This work is driven by an industrial case dealing with heat treatment operation. The first part presents the problem and provide ideas of the solution. Then the knowledge model mixing discrete and numerical constraints is presented. The third section provides filtering elements in order to permit interactive assistance. The last one discusses the designed system. The originality of the proposition lies in the gathering of classical discrete constraints filtering techniques with numerical constraint 2B consistence filtering mechanisms that were necessary to respond to the industrial need.