Manufacture of thick preform composites via multiple pre-shaped fabric mat layers

A method of making multi-layer composite preform having a desired shape and a thickness in the range 0.25 to 7.5 inches and comprising multiple layers of fibrous mats wherein each of said fibrous mats comprises a random carbon-containing fibrous body within which is distributed a polymeric binder and wherein adjacent mat layers are bound together by additional polymer binder, stitching, and interlocking tabs, which method comprises the steps of:

• a.) providing a tool for shaping a fibrous mat layer, said tool including a perforated screen through which a vacuum can be drawn, wherein said tool is reconfigurable such that differently shaped composite preforms can be manufactured in the tool,
• b.) configuring said tool to provide said desired shape,
• c.) delivering chopped fiber tow to said configured tool while drawing vacuum therethrough, to form a fibrous object having said desired shape,
• d.) delivering binder to said fibrous object,
• e.) melting or curing said binder to make a fibrous mat,
• f.) assembling a plurality of said fibrous mats and additional binder into said preform having said desired shape for a carbon-carbon composite part in the substantial absence of cutting or other mechanical modification, and
• g.) heat-pressing the resulting mat assembly into a finished preform.