FRP stands for fiber-reinforced plastic or fiber-reinforced polymer. FRP is comprised of a designated polymer that has been reinforced with fibers. Fiber compositions are typically glass, carbon, or aramid based while the polymer is usually an epoxy, vinyl ester, or polyester thermoset. FRP specifically employs the fiber material to mechanically enhance the strength of the original resin (also referred to as the matrix). 
The extent to which strength is achieved in fiber reinforced plastics is dependent upon the mechanical properties of both the fiber and the matrix, their concentrations relative to one another, as well as the fiber length and orientation/direction within the matrix.
There are a variety of forming processes by which reinforcing fiber material is combined with the matrix in order to yield a fiber reinforced plastic (FRP) shape. Such processes include bladder molding, compression molding, autoclave/vacuum bag, mandrel wrapping, wet layup, chopper gun, filament winding, and pultrusion. Pultrusion shall be the focus of this article as it has become the manufacturing process method of choice for fiber reinforced plastics here at Craftech Industries.
What is pultrusion?
Simply stated, pultrusion is a forming process whereby reinforcing fiber material such as fiberglass roving, mat or cloth, is drawn through a wet bath of resin (typically polyester or other thermosetting resin matrices) in which all material is thoroughly impregnated with the liquid resin. The resulting wet-out fiber is formed to the desired shape and “pulled” through a heated steel die. Inside the die, the curing process begins by precisely controlling elevated temperatures. The laminate solidifies in the exact cavity shape of the die employed as it is continuously “pulled” through the pultrusion apparatus. See video below.
Fiberglass roving provides the high longitudinal strength of pultruded products. Additionally, the roving provides the tensile strength required to pull the other reinforcements (such as mat) through the die. Continuous strand mat provides the high degree of transverse physical properties observed in pultruded products. It is important to note that since pultrusion is a low-pressure process, the fiberglass reinforcements will normally appear close to the surface of the product. This can affect the appearance, resistance properties, or handling of the fiber reinforced plastic products. Surface veils can be added to the laminate construction to displace the fibers from the surface adding a resin-rich finish.
Why use pultruded fiber reinforced plastics?
Fiber reinforced plastics have many desirable qualities, especially as it pertains to strength and chemical resistance. Many design engineers choose the pultrusion process because it yields products that solve many modern problems through their high-strength, lightweight, and maintenance-free properties.
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FEATURES |
DESCRIPTION |
BENEFITS |
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Strength |
Unit strength in tension, flexure, and compression is about 20 times that of steel when properties are combined on the basis of unit density. |
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Lightweight |
Density of FRP is approximately 20% of steel and 60% of aluminum. |
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Corrosion Resistance |
FRP is unaffected by a wide range of corrosive chemicals and environments. |
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Electrical Insulation |
Structural strength and rigidity are provided with dielectric material. |
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Part Consolidation |
Many individual components can be combined into one larger profile. |
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Dimensional Stability |
Stretch-, warp-, and swell-resistant over a wide range of temperatures and physical stresses. |
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Thermal Insulation |
Low thermal conductivity rating of 1/250 of aluminum; 1/60 of steel |
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These attractive properties make FRP the preferred choice of composite material for many uses in industries such as Construction/Industrial, Automotive, Consumer, Wastewater Treatment, Electrical, and Marine just to name a few. Some specific applications found within these industries are as follows:
Construction/Industrial
- Bridges
- Bulkhead Frames
- Cable Trays
- Complete Building Systems
- Cooling Tower Components
- Flooring Supports
- Pipe Supports
- Pre-Fab Walkways, Platforms and Handrail Systems
- Trusses & Joists
- Wind blades
- Window Frames
Automotive
- Automobile Springs
- Automotive Leaf Springs & Bumpers
- Bus Components
- Bus Window Latch Supports
- Dunnage Bars
- Roll-Up Doors/Roll-Up Door Panels
- Spring Bumpers
- Tank Supports
- Truck/Trailer Wall Posts
Consumer
- Ladders
- Light Poles
- Mop, Broom and Brush Handles
- Pruning Poles
- Rake/Shovel Handles
Wastewater Treatment
- Cell Partitions
- Scrubber Components
- Travelling Water Screens
- Water/Waste Water Treatment Sludge Flights
Electrical
- Composite Utility Poles
- Crossarms
- Crossing Gate Arms
- Electrical Enclosures
- Mist Eliminators
- Mounting Braces & Backboards
- Switch Gear Components
- Third Rail Coverboards
- Walk-In Refrigeration Door Jambs
- Boat Dock Power Posts
- Fender Pilings
- Sheetpiles
- Sea Wall/Pylon Design
Many fiber reinforced plastics products are available. Choose from standard polyester, fire-retardant polyester, or fire-retardant vinyl ester for even greater performance demands. With the versatility of the pultrusion process, resin mixtures, reinforcement content and their combination can be augmented to achieve specific properties in a profile.
Interested in getting pricing on pultruded fiber reinforced plastics (FRP) products? Request a free quote!
