1. Manufacturing with Composites
Chapter 19
Manufacturing with Composites

2. Composite - Definition
Structures made of two or more distinct materials
The materials maintain their identity during the process
The materials maintain their identity after the final component is fully formed.

3. Key Points Fabric Types Resin Types Manufacturing Techniques
Curing Techniques
Sandwiches and Honeycombs
Joining of Composites
Pros and Cons of Composites

4. Where are Composites Used?
Recreational boats
Cars
Airplanes and other aircrafts
Aerospace
High performance sporting goods
Appliances, tools, and machinery
Tanks and pipes

5. What is a Composite? First produced about 50 years ago
A “Judicious” combination of two or more materials that produces a “Synergistic” effect
Focusing on using glass, graphite and Kevlar and impregnated with a plastic resin for manufacturing. Areas used recreational

6. Judicious
Implies that the components are carefully selected to provide the desired physical and chemical characteristics

7. Synergistic
The whole product is better than the sum of its individual components
Word coined by Buckminster Fuller
Illustrated concept by using a rope as an example
The term synergy was coined by Buckminster Fuller. He illustrated his concept of synergy with the following analogy. “If one has one hundred individual strings, each is capable of lifting one pound therefore the maximum load of the strings would be 100 pounds. However, if those same strings are twisted, braided, or woven into a rope, the rope will lift far more than a 100 pounds.

8. Composites are made up of a fiber and a matrix
Fiber can be short or long strands of material
Matrix is a the material that holds the fibers together
Natural composites – celery, corn stalks, and sugar cane
Manmade composite – reinforced concrete
Reinforced concrete can be considered a composite with the steel as the fiber and the concrete as the matrix.

9. Composite Classification
Matrix
Material that surrounds the other components
Fillers
Randomly oriented equally dispersed particles
Fiber Reinforcement
Usually the main component in differing forms

10. Simple and Advanced Composites
Simple Composite (Reinforced plastic) – Fiber laid in random directions or very short
Advance Composite – Long fibers are laid in a given direction, long, and continuous

11. Fiber orientation Unidirectional Biaxial (Cross-ply) Laminates
Random orientation
Laminates
Cross layering of unidirectional composites

12. Composite System Categories
Fiber – Resin
Fiber – Ceramic
Carbon – Metal
Metal – Concrete
Metal – Resin
Metal – Elastomer
Fiber – Elastomer
Wood – Resin
When adding fibers to a resin matrix, one cannot predict the properties of the composite by analyzing the components. When a composite is created the fibers and resin create new properties. Example, glass fibers are strong but are vulnerable to damage and a certain plastic weak but, versatile and tough. Combining the two will strengthen the strengths and hide the weaknesses.

13. Typical Fabrics Used in Composites
Glass
Can be long and continuous or short
Can use many different types ex: Soda lime – easy and low cost
Fiberglass white color can be dyed to any color
Kelvar
Can be long and continuous
Same family as nylon
Distinctive yellow color
Graphite (carbon)
Made by burning a material in the absence of oxygen, other elements burn off leaving carbon
Should be called carbon fiber
Always black

14. Strength to Weight

16. Why Chose Glass? Excellent thermal and impact resistance
High tensile strength
Good chemical resistance
Outstanding insulating properties
Lower cost

17. Glass Types E-glass Low cost - $1 per pound
Used in 90% of glass reinforcement
Good electrical resistance
Used in aircraft radomes and antennae and computer circuit boards
Good resistance to sodium carbonate (base)
Good high temperature performance
High strength glass
$6 per pound
S-glass or S2-glass(U.S.)
R-glass (Europe)
T-glass (Japan)
Contains more silica oxide, aluminum oxide, and magnesium oxide
40% to 70% stronger
Originally used for military applications (S2 for commercial)
Good resistance to hydrochloric and sulfuric acid
Good resistance to sodium carbonate (base)
Good high temperature performance
C-glass
Corrosion resistant
Good resistance to hydrochloric and sulfuric acid
Poor high temperature performance

18. Why Chose Graphite? Higher tensile strength and stiffness than glass
Used in high-tech applications where product needs exceptional fiber properties and customer is willing to pay premium

19. Why Chose Kevlar? Highest quality High breaking strength
More impact resistant
Lightest weight
Highest tensile strength

20. Comparisons of Fibers & Steel

21. Comparisons of Fibers & Steel

22. Hybrids Combination of different fibers within a single matrix
Intraply
Interply

23. Hybrids
Interply Knitting
Selective Placement

24. Resins Must be compatible with fibers Two types Thermoplastic
Needs higher temperature processing
Remains plastic and can be reheated and reshaped
Used less
High performance
Higher costs
Higher temperature performance
Better damage resistance
Higher compressive strength
High vibrational damping
Viscoelasticity
Thermosetting
Crosslinks during curing
Sets into final rigid form
Used widely
Lower price tag
Ease of handling
Good balance of mechanical, electrical, and chemical resistance properties

25. Resins – Two Types Thermoplastics Thermosetting ABS PMMS Epoxy
Fluorocarbon (Teflon)
Nylon
Polycarbonate
Polyphenylene sulfide
Polypropylene
Styrene
Vinyl
Vinylidines
Epoxy
Bakelite
Melamine
Polyesters
Urea-formaldehyde
Urethanes
Silicones

26. Manufacturing Techniques
Hand layup or Hand-lay
Pre-preg
Filament winding
Pultrusion

27. Open Mold Processes
Hand Lay-up
Spray-up
Tape-laying
Filament winding

28. Hand layup Oldest, Inexpensive, Little equipment required
Repair technicians and backyard boat builders use this technique with fiberglass
Requires some skill to do
Wasteful use of resin
Product heavier compared to using other techniques
Good for one of a kind products or prototypes

29. Hand layup Method
A form is coated with resin using a paintbrush, roller, swab, spatula or any other method
Fabric is pressed into the resin
Another coat of resin is applied on top

30. Pre-preg Method Fabric saturated with resin
Excess squeezed out by rollers
Cured to B stage, material tacky
Can be stored a week to 10 days if not used right away. Refrigeration lengthens shelf life
Can be wrapped around a mandrel, cut by computer controlled machines or laid up on forms by robots
Must be put under pressure to finish curing

31. Filament Winding Method
Good for convex shapes having no indentations
Individual fibers are drawn through the resin and wrapped around a mandrel
When complete pressure cured, mandrel removed
Good method for aircraft nose cones, radar domes and missile nose cones and bodies

32. Pultrusion Method Good method for selective placement composites
A bundle of arranged fibers are drawn through a resin bath
Then pulled through a selected shape heated die
Cured and cut to size
Good method to create channels, flange beams, T-bars, and other shapes in very long lengths

33. Pultrusion

34. Curing Techniques
Pressure forms
Vacuum bagging
Autoclaving

35. Pressure Form Method Uses a heated internal and external mold
Can be used in mass production, but requires expensive equipment

36. Vacuum Bagging Method Simple and cheapest method
Used after hand layup or pre-preg of material
Piece is placed in a polyethylene, rubber, or airtight flexible bag
Vacuum pull in the bag exerts equal pressure approximately 12 lb/in2
Part or entire bag is heated to cure

37. Autoclaving Method
Used when parts require more than one atmosphere of pressure
An oven that can be sealed and pressure is then applied by air or other gasses

38. Other Composite Forms Sandwiches
Styrofoam, syntactic foam, or polyurethane foam wrapped in fiberglass, Kevlar, or graphite fibers and fused together
Balsa wood could be used as a core to make sailboats
Recent developments using ceramic cores for heat resistance

39. Other Composite Forms Honeycombs
Honeycombed aluminum, Nomex, fiberglass, graphite, or other material wrapped and bonded to composite materials
Used in helicopter blades, truck and aircraft bodies, and some parts of aircraft wings and tail surfaces

40. Joining Composites
Joined in conventional methods by threads, pins, rivets, and other mechanical methods
Thermoplastic polymers joined by fusion welding
Chemical joining
Adhesives

41. Composites vs. Traditional Materials
Pros
Cons
Lighter
Stronger
No fatigue failure
No corroding
Hard to break
Complicated shapes
Delaminate
Blisters
Fabric cutting difficult
Material and curing costs high

42. Environmental Concerns
Reduction of styrene emissions
Exposure limited to 50 parts per million (OSHA)
Hard to meet standards and costly
Achieved by reducing styrene, better transferring to molds, curing in closed systems
Development of biodegradable reinforced plastics
Filling up landfills with computer and car parts, packaging, etc.
Create matrices from soybean protein and use plant-based fibers such as ramie, pineapple leaves and banana stems
Could be used in car and train interiors, computers and as packaging materials
Low cost (when acceptance increases), biodegradable and renewable on a yearly basis

43. Websites