1. Reinforced Plastics

2. Composites Metals are isometric materials
Composites can cut weight by not being isometric and still maintain the strength in the desired directions
Composites are, by definition, solid materials composed of more than one substance in more than one phase

3. Composites

4. Processes Thermoplastic processes –Very short fibers
Matched die/compression molding
RTM
Spray-up
Hand lay-up for wet and prepreg materials
Filament winding and fiber placement
Pultrusion

5. Advanced Composites Long (continuous) fibers
Very high performance reinforcements
Carbon and aramid
Resins are also very high performance
Typically aerospace applications

6. Engineering Composites
Shorter fibers/fiberglass
Lower mechanical properties (stiffness)
Lower performance resins

7. Matrix Materials Resins Both thermosets and thermoplastics can be used
Short fibers are generally used in thermoplastics
Long fibers are generally used with thermosets

8. Matrix Materials Short fiber composites
Less than 0.2 inches (whiskers)
Processed through standard thermoplastic processes
Must pass through gates, runners, and gap between processing screw and barrel walls
Thermoplastics generally benefit greatly from even the short reinforcement materials

9. Matrix Materials – FRP Intermediate length fiber reinforcement
The longer the fibers, the more difficult it is to coat the fibers enough to reap strength benefits
Low viscosity thermosets “wet-out” the materials better than high viscosity thermoplastics
Generally use unsaturated polyester and vinylester resins for FRP

10. Matrix Materials – Advanced
Very long fibers or continuous fibers
Typically used with thermosets, also for “wet- out” reasons
Used generally in advanced composite parts and have greater material property requirements
Generally use epoxy resins

11. Reinforcements Three main types of fibers Fiberglass
Carbon fiber or Graphite
Organic fibers, aramids (kevlar)

12. Fiberglass Spin molten glass Different types of glass can be made
E-glass (improved electrical resistance)
S-glass (high strength)
C-glass (high chemical resistance)

13. Carbon or Graphite Fiber
Originally some distinction was made— now the two refer to the same material
Made from PAN fibers, pitch or rayon fibers
Through heating, raw material looses most non-carbon atoms in the chain
Processing also aligns carbon chains
Carbon fibers have very high modulus (stiffness)

14. Organic Reinforcement Fibers
Aramid fibers have greatest strength and modulus properties of organic fibers
Kevlar is the most commonly used aramid fiber
Aramids are strong and stiff but their greatest value is in impact applications
Front of airplane wings
Armor applications

15. Reinforcement Forms
Fiber manufacturers package the fibers on spools called tows
Fibers are generally converted to other forms after manufacturing
Chopped fibers (including whiskers)
Mat (random)
Woven fibers
Tapes
Prepregs

16. Manufacturing Methods
Thermoplastic processes using short fibers
Injection molding
Extrusion
Minor changes are made to accommodate the fiber reinforcements
All gaps in flow path should be increased
A resin viscosity decrease may be necessary

17. Manufacturing Methods
Matched die or Compression molding
Reduced flow path over injection or extrusion
SMC compression molding allows for continuous fibers, mats or weaves
These processes offer parts that are finished on both sides where most other composite processes do not

18. Manufacturing Methods
Resin transfer molding
Fiber preform is placed in the mold cavity
Preform doesn’t move—resin is pulled/pushed in

19. Manufacturing Methods
Spray-up
Fibers are chopped, coated with resin and sprayed onto the mold

20. Manufacturing Methods
Hand Lay-up (wet and prepreg)
Wet
Prepreg

21. Fiber Orientations
Isometric materials have equal strength in all directions
Composites can be lighter weight by not having strength in the directions that it is not needed
Lay-up still has to have some balance and symmetry

22. Vacuum Bagging Provides for increased part consolidation
Reduces matched die mold costs

23. Manufacturing Methods
Filament winding and fiber placement
Fiber placement has greater accuracy
Fiber placement can wind on less symmetrical and even partially concave mandrels
Tubes, tanks, wind turbine blades and rockets

24. Manufacturing Methods
Roll wrapping
Faster than filament winding
Limited to symmetrical mandrels

25. Manufacturing Methods
Pultrusion
High volume production
Comparable to extrusion but the main processing force is tension
Profile is pulled from the machine

26. Plant Concepts Many of the processes require considerable space
Curing equipment for large parts can be very large (and expensive)
Controlling volatiles (solvents and resins) must be taken care of
Molds can be both expensive and fragile

27. Thank You