If you were to contact a composite manufacturing company like Rock West Composites in search of a reinforcing fiber for a fabricating project, you would be offered carbon fiber, glass fiber, Kevlar, and other materials. As far as carbon and glass fiber go, not a whole lot of people know the difference. They also don’t know how to tell which one is better for a particular job.
Carbon fiber and glass fiber (a.k.a. fiberglass) are reinforcing materials that are combined with epoxy resins to form plastics. Carbon fiber finished products are known as a carbon fiber reinforced plastics (CFRPs); finished glass fiber products are known as a glass fiber reinforced plastics (GFRPs).
More about Glass Fiber
Glass fiber is considered an entry-level composite. A glass fiber fabric actually starts as silica sand that is heated at extremely high temperatures. The high heat allows the sand molecules to be manipulated into strands. Those strands are then spun together to create a thread.
The thread can be woven into fabric for layup fabricating. It can also be spun or braided to create tubing or oddly shaped parts. At any rate, combining the fiber with epoxy resin creates the GFRP.
One of glass fiber’s primary advantages is affordability. Because it costs less to produce, its cost on the retail market is relatively low compared to carbon fiber and Kevlar. Its disadvantage is that it is not as strong as the other two materials. Glass fiber is not as light as either, though it is still lighter than steel and aluminum.
Glass fiber is a good option for hobbyists who do not need the extra weight savings carbon fiber affords. Hobbyists use it all the time to fabricate car body parts.
More About Carbon Fiber
Carbon fiber is a step up from glass fiber in terms of both performance and price. Like glass fiber, it starts out as individual molecules. Creating carbon fiber is a matter of subjecting certain polymers to high heat and pressure in order to force carbon molecules to align end-to-end.
Just like glass fiber, the resulting strands can then be spun to create threads that are woven into fabrics or deployed through spinning and braiding machines.
Carbon fiber’s big advantage is its strength-to-weight ratio. A carbon fiber part of the same size will be 70% lighter than steel and 40% lighter than aluminum. It will also be exponentially stronger than both metals. This exceptional strength-to-weight ratio is why carbon fiber is so important to aerospace and military applications.
Hobbyists may use carbon fiber if they need the extra strength in relation to its cost. Thankfully, the material is easy to work with at home. You do not have to be a composites expert to fabricate something like a drone propeller or a replacement car body panel.
The Deciding Factors
The differences between carbon and glass fiber are fairly subtle to hobbyists. But for the pros, it is a different ballgame. They have to look at three deciding factors to determine which material is better. First up is strength. It’s likely that you’re never going to find a commercial airliner with wings made of fiberglass. Such wings just wouldn’t be strong enough.
The next deciding factor is weight. If you are looking to save on weight at all costs, carbon fiber is the better material. You can go with glass fiber if you need something lighter than steel or aluminum but you don’t need to go extremely light.
Of course, cost in relation to both strength and weight also has to be considered. In many cases, money ends up being the deciding factor.