Process for producing composite material parts by impregnating a specific preform

A method for producing a composite material part comprising unidirectional continuous fibers and a polymer matrix, said method comprising the steps of:

• producing an initial dry preform, formed from unidirectional continuous dry fibers;
• applying a non-woven felt comprising non-woven filaments to a first main face of the initial dry perform, the non-woven felt having a surface mass of between 5 g/m2 and 100 g/m2 and the non-woven filaments having a diameter of between 5 μm and 50 μm;
• needling the non-woven filaments with a forked needling device comprising a plurality of forked needles, each forked needle provided with one notch, so that non-woven filaments are driven by the forked needles and arranged in a direction substantially perpendicular to the unidirectional continuous dry fibers of the initial dry preform so as to obtain a reinforced dry preform, each forked needle having a diameter of between 0.30 mm and 0.60 mm, the notch presenting a width and a depth of between 0.03 mm and 0.1 mm, the needling density being between 150 to 350 punches/cm2;
• and
• impregnating the reinforced dry preform with an impregnation polymer so as to obtain a composite material part, the impregnation polymer constituting the polymer matrix of the composite material part.