A Look at How FRP Is Made

Advanced composites like fiberglass reinforced plastic (FRP) can be manufactured either as molded or pultruded products. Here’s a look at the typical processes for creating these materials.

Material Selection

FRP always begins with a resin base to which glass fibers are added. The resin can be polyester, vinyl ester, or epoxy, depending on the application. Fibergrate uses proprietary resin blends to achieve performance and durability goals for structural and safety engineering applications. Typically, molded grating has 65% - 70% resin whereas pultruded grating has only 30 - 35% resin.

Preparation of Fiberglass

Fiberglass, typically in the form of rovings (bundles of continuous glass filaments), mats, or fabrics, is pulled through a resin bath to impregnate it with the chosen resin. This ensures that the fiberglass is thoroughly coated with resin for optimal strength and durability.

Selection & Inclusion of Additives?

Common additives used in FRP manufacturing include:

1. Fillers: Calcium carbonate, talc, or silica can improve the stiffness, strength, or dimensional stability of the composite.
2. Pigments: Organic or inorganic pigments add color to the final product. Some manufacturers make only a narrow range of colors, but Fibergrate’s range includes custom colors for our clients.
3. UV Stabilizers: These additives are incorporated into the resin to provide additional protection from UV degradation and help prevent discoloration and structural damage.
4. Flame Retardants: These additives help to reduce the flammability of the material and inhibit the spread of flames in case of fire. Our Firewalk phenolic grating is an example of a flame-retardant FRP material.
5. Release Agents: For molded grating, a release agent helps the composite come away from the mold surface with more ease, reducing production defects.?
6. Thickeners: These additives increase the viscosity of the resin, making it easier to apply and reducing dripping or sagging during fabrication.
7. Accelerators and Catalysts: These chemicals are used to speed up the curing process of the resin, reducing manufacturing time and increasing productivity.
8. Modifiers: Various modifiers may be added to the resin to improve specific properties such as impact resistance, chemical resistance, or flexibility.
9. Antioxidants: Antioxidants are additives that inhibit oxidation reactions in the resin matrix, helping to prevent degradation and extend the service life of the FRP.
10. Surface Grit: This additive is typically applied to the surface of the finished product to provide slip resistance.

Manufacturing Pultruded vs. Molded FRP

FRP Pultrusion Process

The manufacturing process of pultruded FRP products starts with long, continuous fiberglass strands infused with resin that are pulled through a series of heated dies. These dies shape the composite material into the desired profile or cross-section while curing the resin. The pultrusion process is continuous, meaning that the material is pulled through the dies constantly. The next step is curing, in which the resin undergoes a chemical reaction that solidifies the material. The pultruded profile is then cooled and cut to the desired dimensions. The final steps include finishing like trimming or sanding.

The pultrusion process efficiently produces high-strength, lightweight, composite materials with a wide range of applications, including construction, automotive, aerospace, marine, and industrial sectors. Pultruded grating is stiffer than molded grating and can span longer distances.

FRP Molding Process

The process of manufacturing molded grating is much more manual. A metal or composite mold is cleaned and treated with a release agent. The layers of fiberglass material are laid inside the mold and impregnated with resin. The mold is closed and the layers are compressed to compact the material and remove trapped air. The composite is then cured via heat, chemical catalysts, or a combination of both. The FRP is then demolded and finished to achieve the desired finish and dimensions.

The molded FRP process allows for the production of complex shapes and parts with relatively low tooling costs, making it suitable for a wide range of applications across various industries. It has a high resin-to-fiber ratio and has excellent corrosion resistance. Depending on the quality of molded FRP, it can also be highly durable and feature a high strength-to-weight ratio.

Here's a closer look at Molded vs. Pultruded FRP Grating and the Benefits of Each Type

Where Is Fibergrate FRP Made?

Fibergrate’s FRP products are manufactured in North America in Texas and Mexico. To learn more about the benefits of using FRP to replace steel, aluminum, wood, and concrete, visit our website.