Fiber-reinforced polymer (FRP) composites are a combination of two discrete phases: a matrix that is often a resin and a fibrous reinforcing system. Along with the type and orientation of the fibers used and the relative proportions of the constituent materials (matrix and fibers), the manufacturing process plays an equally important role in determining the characteristics of the final composite product. Hence, it is necessary to judiciously choose the manufacturing process that would result in optimal properties of the composite as well as improved economics. The choice of the manufacturing process will also depend on the user needs, performance and appearance requirements, size and surface complexity of the desired product, production rate and available equipment/tooling assembly. There are several manufacturing processes, which may be broadly classified into three categories:

1. Manual processes, including methods such as wet lay-up and contact molding 2. Semi automated processes, including methods such as compression molding and resin

infusion 3. Automated processes, including methods such as pultrusion, filament winding, and injec-

tion molding

Introduction ...................................................................................................................................... 15 Manual Manufacturing Processes .................................................................................................... 16

Wet Lay-Up and Prepreg ............................................................................................................. 16 Contact Molding.......................................................................................................................... 18

Semiautomated Manufacturing Processes ....................................................................................... 19 Resin Infusion under Flexible Tooling ........................................................................................ 19 Compression Molding .................................................................................................................20

Automated Manufacturing Processes ..............................................................................................22 Pultrusion Process .......................................................................................................................22 Filament Winding ........................................................................................................................23 Resin Transfer Molding...............................................................................................................25

Quality Assurance and Quality Control ...........................................................................................26 Visual and Mechanical Inspection ..............................................................................................26 Mechanical Testing .....................................................................................................................27 Monitoring Cure Kinematics and Durability ..............................................................................28 Nondestructive Testing ................................................................................................................29

Conclusions ......................................................................................................................................30 References ........................................................................................................................................30

All these manufacturing processes can also be fine-tuned by the manufacturer in terms of the total cost involved in fabricating the composite part, the level of precision involved to obtain the desired quality, varying degrees of compaction provided by the tools and pre-/post-cure of the resin.