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A: At DEFI structural fiberglass, we use three methods of fiberglass—pultrusion, open-molded, and hand layup. Pultrusion is something you would typically see in a fiberglass channel, beam, or even square tube that we use in handrails and ladders.
Open molded typically refers to the fiberglass grating—open molded grating.
The hand layup is when we would use a hand layup mold to make a special product or shape.
If you found us by searching Google for “fiberglass reinforced plastic,” you probably got a lot of extra results you didn’t expect. You might have seen several different terms that include fiberglass and the abbreviated form, “FRP.”
It can be quite confusing, especially when you learn that not all fibers in FRP are—glass. That’s right, FRP is a broad term for any plastic that is reinforced with some type of fibers. In the US you hear FRP the most and it refers to what we specialize in—specifically structural fiberglass. To know what structural FRP is though, you need to know what’s at its core—fiberglass.
Fiberglass is created by spinning melted glass in such a way that it creates fiber strands of glass. It almost looks like the consistency of cotton candy. In and of itself these fibers can be a usable product, but more often than not, fiberglass is used in a composite like FRP.
A composite is a combination of materials that when combined, creates a new substrate. The composite is often comprised of a matrix or base material and reinforcement material. The matrix can be metal, plastic, or even ceramic. Fiberglass, in this case, is the reinforcement material that makes the composite stronger than the parts on their own.
What Is FRP?
FRP is an abbreviation for fiber-reinforced plastic or polymer in some circles. Not to get too scientific, a polymer is a chemical compound with a long chain-like structure of molecules. Some polymers are natural like rubber, others are synthetic such as polypropylene. Pliable synthetic polymers such as polypropylene are called thermoplastics while more rigid ones such as polystyrene are called thermosets. That FRP is the raw material that is manipulated to form the various profiles we create for structural building, hence it’s called—structural fiberglass.
Structural Fiberglass are building components manufactured using standard fiberglass profiles such as angles, tubes, I-beams, and other shapes.
Most of our products are made using three different fabrication methods depending on the end-use. As Arthur mentioned in the video, we use pultrusion, open mold process, and hand layup.
Each process has its unique applications. Most of our top-selling FRP products from DEFI are fabricated using the pultrusion method. Due to the nature of the pultrusion process, this method gives several advantages over other methods such as increased strength, higher corrosion resistance, and better impact resistance.
Pultrusion is a technique for creating continuous structural fiberglass shapes but without distorting the cross-sections. This process involves pulling the three laminates mentioned before through a heated die that forms it to specs. The fiberglass reinforcement material is usually in continuous form—hollow spools, roving, or filament mats.
The resin liquid mix that is used to bind the fibers is cured within a catalytic reaction that is caused by the heat from the die. The resin then becomes rigid and takes on the shape of the die’s cavity.
The pultrusion process is used in a wide range of industries for many different applications. This is because they can duplicate the strong properties of traditional materials while correcting the weak properties.
For example, pultruded structural fiberglass grating duplicates the strength of steel grating but is corrosion-resistant, unlike steel. While there are several variations of the pultrusion method such as reciprocating pullers or caterpillar pullers—the concept is the same.
Open molding is one of the oldest processes for creating FRP products. There are no technical skills or complex machines needed. It’s ideal for low-volume, labor-intensive, larger products such as vessels, tanks, car bodies, and oil pipelines.
The mold contains the structural shape that is needed therefore careful order of steps must be taken. For example, to have the final product shiny or have texture, the surface finish of the mold needs to reflect that specification.
If the external surface of the product needs to be smooth, you use a female mold to fabricate the product. In the same manner, if the inside specification is smooth, then you pour on the male mold. Either way, molds must be pristine or the finished product will reflect any defects in the mold itself.
Unlike pultrusion, since the resin is viscous and is being poured into the mold, it needs to have a releasing agent. Without a releasing agent, the product may not come free from the mold, rendering it unusable. Using a thin coating of wax, polyvinyl alcohol, or mylar film allows for a smooth release of the finished product after curing.
Hand layup is an open mold process and as the name suggests, this process is all done by hand. The quality is heavily dependent on the skill of the person crafting it. A good example of hand layup process products are safety helmets and custom shapes.
There’s a reason that our number one seller is pultruded fiberglass products. The combination of the raw materials used and the pultrusion process give structural FRP benefits steel just can’t match:
In addition to those benefits, there are inherent advantages that can’t be duplicated with any other material other than fiberglass.
There are quite a few applications in manufacturing plants that have chemical corrosives or are exposed to harsh outdoor environments. Structures constructed from FRP easily withstand the day-to-day abuse of these environments with no damage. Steel, on the other hand, can rust, flake, and in some neglected situations—break, causing serious injury. You never have to worry about FRP’s structural integrity being compromised in these environments.
Another reason why using structural FRP is such an advantage for many applications comes down to pure economics. The manufacturing process of pultrusion produces the highest output volume at the lowest conversion cost.
FRP is much lighter, cheaper to ship, and requires no maintenance. Of course, the installation of steel often needs cranes and special heavy lifting equipment. FRP can be moved with a forklift or even carried by hand.
The safety of steel can be compromised by so many different hazards. Electrical, corrosives, the elements. Safety is crucial in both the workplace infrastructure and public-use structures. At DEFI we produce FRP handrails in various designs that exceed OSHA requirements.
Special resin combinations can be used to offer traits such as heat and fire resistance in our vinyl ester and polyester handrails. We can also “bake in” any color including safety yellow and even UV barrier coatings for world-class UV resistance.
Our fiberglass products are as customized or as universal as your application requires. We have common profiles and structures in stock and also a full custom shop for your unique projects.
Contact us today and let’s build it better together.
Various glass chemical compositions described below from ASTM C 162 were developed to provide combinations of fibre properties directed at specific end use applications.
A GLASS
Soda lime silicate glasses used where the strength, durability, and good electrical resistivity of E Glass are not required.
ADVANTEX®
Calcium aluminosilicate glass introduced to provide most of the advantages of ECR glass with the cost of E-glass. Boron free composition reduces pollution.
C GLASS
Calcium borosilicate glasses used for their chemical stability in corrosive acid environments. Superior chemical resistance when compared to E glass.
D GLASS
Borosilicate glasses with a low dielectric constant for electrical applications.
E GLASS
Alumina-calcium-borosilicate glasses with a maximum alkali content of 2 wt.%. Commonly used as general purpose fibres where structural strength and high electrical resistivity are required. E glass has relatively poor acid resistance.
ECRGLAS®
Calcium aluminosilicate glasses with a maximum alkali content of 2 wt.% used where strength, electrical resistivity, and acid corrosion resistance are desired. Superior chemical resistance when compared to C glass. Certain ECR glass formulations also have good solubility resistance to dilute hydro fluoric acid.
AR GLASS
Alkali resistant glasses composed of alkali zirconium silicates used in cement substrates and concrete.
R GLASS
Calcium aluminosilicate glasses used for reinforcement where added strength and acid corrosion resistance are required.
S-2 GLASS®
Magnesium aluminosilicate glasses used for textile substrates or reinforcement in composite structural applications which require high strength, modulus, and stability under extreme temperature and corrosive environments.
The chemical resistance of glass fibres to the corrosive and leaching actions of acids, bases, and water is expressed as a percent weight loss. The lower this value, the more resistant the glass is to the corrosive solution.
The test procedure involves subjecting a given weight of 10 micron diameter glass fibres, without binders or sizes, to a known volume of corrosive solution held at 96°C. The fibres are held in the solution for the time desired and then are removed, washed, dried, and weighed to determine the weight loss. The results reported are for 24-hr (1 day) and 168-hr (1 week) exposures.
As the table shows, the chemical resistance of glass fibres depends on the composition of the fibre, the corrosive solution, and the exposure time. It should be noted that glass corrosion in acidic environments is a complex process beginning with an initial fast corrosion rate. (Note the similarity in weight loss between the 1-day and 1-week samples treated with acid in the table.)
With further time, an effective barrier of leached glass is established on the surface of the fibre and the corrosion rate of the remaining unleached fibres slows, being controlled by the diffusion of compounds through the leached layer. Later, the corrosion rate slows to nearly zero as the non-silica compounds of the fibre are depleted.
For a given glass composition, the corrosion rate may be influenced by the acid concentration (see graph), temperature, fibre diameter, and the solution volume to glass mass ratio. In alkaline environments weight loss measurements are more subjective as the alkali affects the network and reprecipitates the metal oxides. Tensile strength after exposure is a better indicator of the residual glass fibre properties as shown in else where for 24-hour exposure at 96°C.
Chemical Properties @ 96°C Immersion Temperature DurabilityFor more wholesale epdm sealing stripinformation, please contact us. We will provide professional answers.