1. Molding and Machining Composites
By Patrick Thurston

2. Introduction to Composites
Composites are the combination of two or more materials that when bonded together take on each others properties.
Examples of Composites are: Plywood, Carbon Fiber Reinforced Polymer ext.

3. High Strength Composites
High strength composites are generally made of super strong fibers mixed with a type of epoxy or polymer.

4. Common Applications
Composites are used in a number of different products including skis, golf clubs, race cars, and space crafts.

5. Difficulties in Machining
High strength composites require the use of special tools and equipment in order to machine them.
Carbon Fiber composites have high tensile strengths of 120,000 psi and higher.

6. Molding Methods Vacuum Bag Molding: Pressure Bag Molding:
A two sided mold is used with a vacuum bag that presses the composite into the mold.
Pressure Bag Molding:
Almost the same process as vacuum bag molding except a bag is inflated forcing the composite into the mold.
Autoclave Molding:
This is the same as vacuum bag molding except the whole mold is placed in an autoclave to improve the strength of the product.
Resin Transfer Molding
Resin Transfer Molding is done by placing the reinforcing fiber inside the mold first, and then the resin is “pumped” into the mold.

7. Machining High Strength Composites
Machining High Strength Composites such as carbon fiber reinforced polymer is possible but requires diamond or “diamondlike” coated Tools.
The Diamond coated tools are very expensive but can be used again and again.

8. Molding VS. Machining Pros Cons Pros Cons Less wasteful of materials.
Can make
complex parts.
Cons
Expensive molds
and machine.
Would need to be
subbed out for
highest strength
materials.
Pros
We have
the equipment.
No waiting
for parts.
Cons
Would take a lot of
hours in the shop
to manufacture.
Expensive tools.
May not be able to
manufacture some
parts.

9. Questions?