Owing to various end-uses and good performance/cost ratio, the multifunctional nonwoven- based products have been significantly developed within a decade. Such products are mostly dedicated to niche or limited markets and are preferably high valued products. Therefore, in order to face the international competition, designers are strongly involved in development of new advanced products in order to satisfy more complex requirements and specifications with limited time and cost. One of the objectives of the design procedure is to define a relevant process operation setting space (acceptable range of design factors) adapted to the selected process. This paper presents an original method for determining such relevant space. The proposed procedure can save a certain amount of trials by investigating interesting zones of process operation settings with a limited experiment design. This procedure permits to support the designers during the learning and the optimization phases.