Composites Industry Overview

Industry Terms
World Composites Organizations
Associations with Tangential Composites Focus
Industry Information
Composites Industry News

In a marketplace where demands for product performance are ever increasing, composite materials have proven to be effective in reducing costs and improving performance. Composites solve problems, raise performance levels, and enable the development of many new products.

In the United States, composites manufacturing is a 25 billion dollar a year industry, and it is one of the few industries in which the U.S. is more advanced than most competitors abroad. There are five to seven thousand composites related manufacturing plants and materials distributors across the U.S. These facilities employ more than 236,000 people. An additional 250,000 people are employed in businesses that support the composites industry, including materials suppliers, equipment vendors, and other support personnel.

About 90% of all composites produced are comprised of glass fiber and either polyester or vinyl ester resin. 65% of composites are manufactured using the open molding method and the remaining 35% are produced using closed molding or continuous molding methods.

Composites are broadly known as reinforced plastics. Specifically, composites are a reinforcing fiber in a polymer matrix. Most commonly, the reinforcing fiber is fiberglass, although high strength fibers such as aramid and carbon are used in advanced applications.

The polymer matrix is a thermoset resin with polyester, vinyl ester, and epoxy resins most often being the matrix of choice. Specialized resins, such as phenolic polyurethane, and silicone are used for specific applications.

Common household plastics such as polyethylene, acrylic, nylon, and polystyrene are known as thermoplastics. These materials may be heated and formed and can be re-heated and returned to the liquid state.

Composites typically use thermoset resins, which begin as liquid polymers and are converted to solids during the molding process. This process, known as crosslinking, is irreversible. Because of this, these polymers are known as thermosets and cannot be melted and reshaped.

The benefits of composite materials have fueled growth of new applications in markets such as transportation, construction, corrosion-resistance, marine, infrastructure, consumer products, electrical, aircraft and aerospace and appliances and business equipment. The benefits of using composite materials include:

High Strength – Composite materials can be designed to meet the specific strength requirements of an application. A distinct advantage of composites over other materials is the ability to use many combinations of resins and reinforcements, and therefore custom tailor the mechanical and physical properties of a structure.

Light Weight – Composites are materials that can be designed for both light weight and high strength. In fact, composites are used to produce the highest strength to weight ratio structures known to man.

Corrosion Resistance – Composites products provide long-term resistance to severe chemical and temperature environments. Composites are the material of choice for outdoor exposure, chemical handling applications, and severe environment service.

Design Flexibility – Composites have an advantage over other materials because they can be molded into complex shapes at relatively low cost. The flexibility of creating complex shapes offers designers a freedom that hallmarks composites achievement.

Durability – Composite structures have an exceedingly long life span. Coupled with low maintenance requirements, the longevity of composites is a benefit in critical applications. In a half-century of composites development, well-designed composite structures have yet to wear out.

Today, the composites industry continues to grow as a major provider of products, as more designers, engineers, and manufacturers discover the benefits.

As a Certified Composites Technician, you will have the opportunity to be a part of the success of composites and you will benefit from your enhanced knowledge of the industry.

The Composites Industry

Consumer Composites
The composites industry has been in place for over fifty years, and consumer products such as boats, automobiles and recreational products have been manufactured since the early 1950s. Typically, although not always, consumer composites involve products that require a cosmetic finish, such as boats, recreational vehicles, bathwear, and sporting goods. In many cases, the cosmetic finish is an in-mold coating known as gel coat. Consumer products make up a large portion of the overall composites market.

Industrial Composites
A wide variety of composites products are used in industrial applications, where corrosion resistance and performance in adverse environments is critical. Generally, premium resins such as isophthalic and vinyl ester formulations are required to meet corrosion resistance specifications, and fiberglass is almost always used as the reinforcing fiber.

In many cases, cosmetic finishes are secondary to the performance of the product. Industrial composite products include underground storage tanks, scrubbers, piping, fume hoods, water treatment components, pressure vessels, and a host of other products.

Advanced Composites
This sector of the composites industry is characterized by the use of expensive, high-performance resin systems and high-strength, high-stiffness fiber reinforcement. The aerospace industry, including military and commercial aircraft of all types, is the major customer for advanced composites.

These materials have also been adopted for use in sporting goods, where high-performance equipment such as golf clubs, tennis rackets, fishing poles, and archery equipment, benefits from the light weight – high strength offered by advanced materials. There are a number of exotic resins and fibers used in advanced composites, however, epoxy resin and reinforcement fiber of aramid, carbon, or graphite dominates this segment of the market.

What Are Composites?

Wood is a good example of a natural composite. Wood is a combination of cellulose fiber and lignin. The cellulose fiber provides strength and the lignin is the "glue" that bonds and stabilizes the fiber.

Bamboo is a very efficient wood composite structure. The components are cellulose and lignin, as in all other wood, however bamboo is hollow. This results in a very light yet stiff structure. Composite fishing poles and golf club shafts copy this natural design.

Plywood is a man-made composite combining natural and synthetic materials. Thin layers of wood veneer are bonded together with adhesive to form flat sheets of laminated wood that are stronger than natural wood.

There are other man-made combinations of natural materials that form useful composites. The ancient Egyptians manufactured composites! Adobe bricks are a good example. The combination of mud and straw forms a composite that is stronger than either the mud or the straw by itself.

Concrete and steel combine to create structures that are rigid and strong. This is a classic composite material where there is a synergy between materials. In this case, synergy means that the composite (or combination) of materials is stronger and performs better than the individual materials. Concrete is rigid and has good compression strength, while steel has high tensile strength. The result is a structure that is strong in both tension and compression.

Another composite product with which we are all familiar is the rubber tire. A typical car tire is a combination of a rubber compound and reinforcement such as steel, nylon, aramid, or other fibers. The rubber acts as a matrix, holding the reinforcement in place. The matrix is the glue that holds the fiber in place.

While the broad definition of composites is accurate, it is too general. A specific definition of composites for our purposes is: "A combination of fiber reinforcement and a polymer matrix." For example, polyester resin is the matrix and glass fiber is the reinforcement. The glass fiber provides strength and stiffness, and the resin provides shape and protects the fibers.

Why Composites Are Different

Composites differ from metals due to the wide range of material combinations that can be used. Because of this, it is difficult to use a "handbook" approach to composites design. For example, if one were looking for a steel I-beam to span 20 feet and carry a 2000-pound load, you could simply open a structural steel handbook and choose the proper beam thickness and flange width from a chart.

Composites are more complicated. The performance characteristics of composites can be varied to a tremendous degree and there is no such thing as a "generic" or typical composite. The very thing that makes composites a highly adaptable engineering material also makes them more difficult to describe.

There are many combinations of resins and reinforcements used in composites. Each specific material contributes to specific unique properties in the finished FRP product.

There are a number of different resins used in composites. These include: polyester, vinyl ester, modified acrylic, epoxy, phenolic, and urethane resin systems. The list goes on; however, the important point to note is that each of these resins has specific performance characteristics. For example, if a product needs to be corrosion resistant, isophthalic or vinyl ester resin might be used. If high strength is critical, an epoxy might be the resin of choice. If product cost is an issue, polyester resin is most commonly used. In the realm of polyester resins alone, different formulations will be used if cosmetics are important, if enhanced corrosion resistance is required, if elevated temperatures will be encountered, or if cost is an overriding factor. The resin system is selected based on the functional and cost requirements of the product.

In addition to different resins, various types of reinforcement fibers are used in composites. Glass fiber is used in over 90% of all composites. However, if required, advanced fibers such as Kevlar or carbon fiber offer high level performance at a significant price. In the realm of glass fiber, there are many "styles" of reinforcement. Depending on the molding process and the strength requirements of the product there are many options.

Glass fiber is available in random fiber orientation in the form of chopped strand mat. There are also lightweight textile fabrics, heavy woven materials, knitted fabrics, and unidirectional fabrics that all serve specific purposes in composite design.

To maximize the cost/benefit of composite products, the component materials must be custom tailored to the application. The ability to adapt composites over a wide range of requirements makes them different from other materials.

The Advantages of Composites

High Specific Strength
Specific strength is a term that relates strength to weight. Composites have a higher specific strength than many other materials. To understand this, consider the following example:

Compare a ¼ inch diameter steel rod to a ¼ inch diameter fiberglass composite rod.

• The steel rod will have higher tensile and compressive strength, but will weigh more.
• If the fiberglass rod were increased in diameter to the same weight as the steel rod, it would be stronger.

Ability to Form Shapes
Composites can be formed into complex and accurate shapes easier than other materials. This gives designers the freedom to create any shape or configuration. Boats are a good example of the success of composites. Boats can be made out of a variety of materials – wood, aluminum, steel, and even cement! Why are most pleasure boats today built from fiberglass composites? The reason is that composites can be easily molded into complex shapes which improve boat design.

Inherent Durability
How long do composites last? The answer is, we do not know…because we have not come to the end of the life of many original composites. There are numerous examples of composites that have been is service for forty to fifty years.

In 1947 the U.S. Coast Guard built a series of forty-foot patrol boats, using polyester resin and glass fiber. These boats were used until the early 1970s when they were taken out of service because the design was outdated. Extensive testing was done on the laminates after decommissioning, and it was found that only 2-3% of the original strength was lost after twenty-five years of hard service.

There are numerous examples of boats, buildings, and other composites structures built in the 1950s, which are still in service. The bodies of the original 1953 Corvette are fiberglass, and with the exception of cosmetic repairs, are still structurally sound.

There are case histories of fiberglass ductwork being in service in chemical manufacturing plants for over twenty-five years - operating in harsh chemical environments twenty-four hours a day, seven days a week. How long do composites last? In many cases, over fifty years and still counting!

Low Relative Investment
One reason the composites industry has been successful is because of the low relative investment in setting-up a composites manufacturing facility. This has resulted in many creative and innovative companies in the field.

Today, many of the largest composites molding companies have their roots in small entrepreneurial companies that entered the business because of the low initial investment. There are processes, such as thermoplastic injection molding, which require large multi-million dollar investments in equipment. Open molding of composites requires a much more moderate investment in equipment and molds. Although today, complying with regulations has added to the cost of being in the composites business, the overall cost to enter the industry is less then many other manufacturing ventures.

History of the Composites Industry

The 12th century Mongols made the advanced weapons of their day with archery bows that were smaller and more powerful than their rivals. These bows were composites structures made by combining cattle tendons, horn, bamboo, and silk which bonded with natural pine resin. The tendons were placed on the tension side of the bow, the bamboo was used as a core, and sheets of horn were laminated to the compression side of the bow. The entire structure was tightly wrapped with silk using the rosin adhesive. These 12th century weapons designers certainly understood the principles of composite design. In recent times some of these 700-year old museum pieces were strung and tested. They were about 80% as strong as modern composite bows.¹

In the late 1800s canoe builders were experimenting with gluing together layers of kraft paper with shellac to form paper laminates. While the concept was successful, the materials did not perform well. Because the available materials were not up to the job, the idea faded.

In the years between 1870 and 1890, a revolution was occurring in chemistry. The first synthetic (man-made) resins were developed which could be converted from a liquid to a solid by polymerization. These polymer resins are transformed from the liquid state to the solid state by crosslinking the molecules. Early synthetic resins included celluloid, melamine, and Bakelite.

In the early 1930s two chemical companies that were working on the development of polymer resins were American Cyanamid and DuPont. In the course of their experimentation, both companies independently formulated polyester resin for the first time. In the same time period, Owens-Illinois Glass Company began weaving glass fiber into a textile fabric on a commercial basis.

During the time between 1934 and 1936, experimenter Ray Green, in Ohio, combined these two new products and began molding small boats. This marks the beginning of modern composites. During World War II the development of radar required non-metallic housings, and the U.S. military advanced the fledgling composites technology with many research projects. Immediately following World War II composite materials emerged as a major engineering material.

The composites industry began in earnest in the late 1940s and developed rapidly through the 1950s. Most of the composites processing methods used today were developed by the year 1955. Open molding, hand lay-up, chopping, compression molding, filament winding, resin transfer molding, vacuum bagging, and vacuum infusion were all developed and used in production between 1946 and 1955. The products manufactured from composites during this period included: boats, car bodies (Corvette), truck parts, aircraft components, underground storage tanks, buildings, and many other familiar products.

Footnotes:
¹ Gerald Shook, Reinforced Plastics Tutorial