The present invention involves a method and system for manufacturing a multiple density substrate for impact energy absorption with a mold having a mold cavity of a predetermined shape. The substrate is integrally formed by the method comprising providing a first set of unbonded pre-expanded beads having a first density and a second set of unbonded pre-expanded beads having a second density, loading a portion of the mold with the first set of unbonded beads at a predetermined location in the mold sufficiently to leave a void in the mold, and separately injecting the loaded mold portion with a sufficient second set of unbonded beads into the void. The method further includes bonding the first and second sets of beads together with heat to define a molded set of bonded beads having the predetermined shape and cooling the molded set of bonded beads sufficiently to define the substrate.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a division of U.S. application Ser. No. 09/560,233 filed Apr. 28, 2000, now U.S. Pat. No. 6,379,595.
