Abstract: Compared to the prepreg/autoclave process usually used in aerospace, the automatic placement of dry fiber/liquid molding can manufacture the same composite materials, as measured by fiber volume content and good mechanical properties, but at a lower cost. The preforms are made of dry fiber tows with heating and pressing by Automatic Fiber Placement (AFP) machine, and their permeability, fiber volume contents and compression characteristics have a great influence on the properties of the composite materials. In this paper, the preforms of different interlayer structures were prepared by adjusting the temperature and pressure of the dry fiber tow within the automatic placement technology. The influence of the automatic placement process parameters on the performance of the preforms was studied. The results show that at a constantly held pressure, as the temperature increases, the thickness and permeability of the preforms decrease, and their deformation resistance and fiber volume content increase. The volume content is 58.45% at 175 ℃. Also, at a constantly held temperature, as the pressure increases, the thickness, permeability, fiber volume content and deformation resistance of the preforms have the same changing trend as increasing temperature, and the volume content is 55.39% at 0.2 MPa. This is mainly related to physical/chemical changes of dry fiber surface with the styling agent and the flow guiding fiber.

Key words: automatic placement, preform, permeability, compression characteristics, fiber volume content, composites