Seal putty Soft plastic film Atmospheric pressure Felt for pumping ↓ Vacuum pump Laminate Separator Figure 2.4 Vacuum Molding Accelerator Biological protection 20 kw-10 MeV Laminate under pressure Electron beam X rays e≤300mm e≤25mm Figure 2.5 Electron Beam or X-ray Molding 2.1.3 Molding with Vacuum This process of molding with vacuum is still called depression molding or bag molding.As in the case of contact molding described previously,one uses an open mold on top of which the impregnated reinforcements are placed.In the case of sandwich materials,the cores are also used (see Chapter 4).One sheet of soft plastic is used for sealing(this is adhesively bonded to the perimeter of the mold).Vacuum is applied under the piece of plastic (see Figure 2.4).The piece is then compacted due to the action of atmospheric pressure,and the air bubbles are eliminated.Porous fabrics absorb excess resin.The whole material is polymerized by an oven or by an autoclave under pressure(7 bars in the case of carbon/epoxy to obtain better mechanical properties).or with heat,or with electron beam,or x-rays;see Figure 2.5).This process has applications for aircraft structures,with the rate of a few parts per day (2 to 4). 2003 by CRC Press LLC2.1.3 Molding with Vacuum This process of molding with vacuum is still called depression molding or bag molding. As in the case of contact molding described previously, one uses an open mold on top of which the impregnated reinforcements are placed. In the case of sandwich materials, the cores are also used (see Chapter 4). One sheet of soft plastic is used for sealing (this is adhesively bonded to the perimeter of the mold). Vacuum is applied under the piece of plastic (see Figure 2.4). The piece is then compacted due to the action of atmospheric pressure, and the air bubbles are eliminated. Porous fabrics absorb excess resin. The whole material is polymerized by an oven or by an autoclave under pressure (7 bars in the case of carbon/epoxy to obtain better mechanical properties), or with heat, or with electron beam, or x-rays; see Figure 2.5). This process has applications for aircraft structures, with the rate of a few parts per day (2 to 4). Figure 2.4 Vacuum Molding Figure 2.5 Electron Beam or X-ray Molding TX846_Frame_C02 Page 19 Monday, November 18, 2002 10:40 AM © 2003 by CRC Press LLC