Preliminary Material Combinations(PMCs) 297 Substituting in the values yields: 10-2m21MP 1000 Pa-sec 0.2 mm -=5x103 mm/sec Time required to traverse the thickness of the preform: h 0.2mm 1=-= -=40sec. u5×10-3mm/sec For the length of the die of 50 cm,the maximum rate of production R would be: R='=50cm or 1.25 cm/sec I 40 sec =1.25 cm sec 3.2.Fibers with Clinging Powders In the powder clinging process,the matrix powder is made to stick to the surface of the fibers.Figure 8.5 shows a schematic of the process. First,the dry fiber tow is fed from a creel to an air-conditioned spreader. The tow is spread to expose the fiber and grounded in order to pick up charge powder.By spreading a tow to expose virtually every fiber,it is easier to get the liquid resin to the surface of every fiber and it takes less pressure to force a polymer melt through a fiber bed.The fiber tow then enters into a heated chamber where matrix powder is electrified such that it carries an electrical charge,then it is fluidized.The powder is deposited on the band of fibers due to static electricity.At the next station of the Lean Phase 两州州 Air Dense Diffuser Plate Phase Electric Potential Let-off Air Comb Oven Take-up Winder Spreader Winder Air Tension Fluidized Pull Control Bed Rollers FIGURE 8.5 Process to get matrix powders to cling to fibers (reproduced from"The processing science of thermoplastic composites,"by J.D.Muzzy and J.S.Colton,in Ad- vanced Composites Manufacturing,T.G.Gutowski,ed.,with permission from Wiley Interscience).3.2. Fibers with Clinging Powders In the powder clinging process, the matrix powder is made to stick to the surface of the fibers. Figure 8.5 shows a schematic of the process. First, the dry fiber tow is fed from a creel to an air-conditioned spreader. The tow is spread to expose the fiber and grounded in order to pick up charge powder. By spreading a tow to expose virtually every fiber, it is easier to get the liquid resin to the surface of every fiber and it takes less pressure to force a polymer melt through a fiber bed. The fiber tow then enters into a heated chamber where matrix powder is electrified such that it carries an electrical charge, then it is fluidized. The powder is deposited on the band of fibers due to static electricity. At the next station of the Preliminary Material Combinations (PMCs) 297 Substituting in the values yields: u = = × − 10 1 − 5 10 12 m 3 1000 Pa - sec MPa 0.2 mm mm / sec 2 Time required to traverse the thickness of the preform: t h u = = × = − 0 2 40 . mm 5 10 mm / sec sec. 3 For the length of the die of 50 cm, the maximum rate of production R would be: R L t == = 5 4 1 25 1 25 0 cm 0 sec . cm / sec or . cm / sec FIGURE 8.5 Process to get matrix powders to cling to fibers (reproduced from “The processing science of thermoplastic composites,” by J. D. Muzzy and J. S. Colton, in Ad￾vanced Composites Manufacturing, T. G. Gutowski, ed., with permission from Wiley Interscience)