GFRP: Manufacturing process, properties and application
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First developed in the mid 1930s, glass fibre-reinforced plastics (GFRP) were used for high-temperature electrical application. In 1967 the architectural advantages were discovered with the attempted destruction of Disneyland’s “House of the Future”. The futuristic house was built entirely of fibreglass, and when the attraction was no longer alluring visitors, it was scheduled to be destroyed. Staggeringly, the wrecking ball merely bounced off the structure, which led to discovering the opportunities for GFRP. By 1994, nearly 300,000 tons of composite materials were used in the building industry. Today, GFRP is used in electronics, the aerospace industry, automobile industry and many others, making it a ubiquitous material.

 

Manufacturing process of GFRP

Step 1 - Batching

In the initial stage of producing GFRP, materials must be carefully weighed in exact quantities and thoroughly mixed (batched). More than half the mix is silica sand, which is the basic building block of any glass. 

 

Step 2 - Melting

From the batch house, pneumatic conveyor sends the mixture to a high temperature (ca. 1400ºC) furnace for melting. The furnace is typically divided into three sections, with channels that aid glass flow. The first section receives the batch, where melting occurs and uniformity is increased, ensuring there’s no bubbles. The high temperature see to it that the sand and other ingredients dissolve into molten glass. The molten glass then flows into the refiner, where its temperature is reduced to 1370ºC.

 

Step 3 - Fiberisation

GFRP formation, or fiberisation, involves a combination of extrusion and attenuation. In extrusion, the molten glass passes out of the forehearth through a bushing made of an erosion-resistant platinum alloy with very fine orifices. Bushing plates are heated electronically, and their temperature is precisely controlled to maintain a constant glass viscosity. Water jets cool the filaments as they exit the bushing at approximately 1204ºC.

 

Attenuation is the process of mechanically drawing the extruded streams of molten glass into fibrous elements called filaments. A high-speed winder catches the molten streams and because it revolves at a circumferential speed of  ca. 3 km per minute (much faster than the molten glass exiting the bushing), tension is applied, drawing them into thin filaments.

 

Step 4 - Coating

In the final stage, a chemical coating is applied. This typically adds 0.5 to 2.0 percent of weight and may include lubricants, binders and/or coupling agents. The lubricants help to protect the filaments from abrading and breaking as they are collided and wound into forming packages, and later, when the filaments are processed by weavers or other converters into fabrics or other reinforcement forms. 

 

Step 5 - Drying and packaging

Finally, the drawn, sized filaments are collected together into a bundle, forming a glass strand composed of 51 to 1,624 filaments. The strand is wound onto a drum into a forming package that resembles a spool of thread. The forming packages, still wet from water cooling and sizing, are then dried in an oven. Afterwards, they are ready to be packaged and shipped or further processed into chopped fibre, roving or yarn.

 

Properties of GFRP

  • Mechanical strength: GFRP has a specific resistance greater than steel. 

  • Lightweight: Low weights ensure faster installation, less structural framing, and lower shipping costs.

  • Electrical characteristics: Good electrical insulator even at low thickness.

  • High resistance: Resistant to salt water, chemicals, and is unaffected by acid rain.

  • Incombustibility: Being a mineral material, GFRP is naturally incombustible. It does not propagate or support a flame, and it does not emit smoke or toxicity when exposed to heat.

  • Thermal conductivity: Low thermal conductivity makes it highly useful in the building industry.

  • High durability: GFRP does not rot and remains unaffected by rodents and insects. It does not show loss of laminate properties after 30 years. 

     

Application of GFRP

GFRP can be used for both interior and exterior fixtures in a variety of shapes, styles, and textures, in new buildings or restorative projects. GFRP finds application in an extensive array of markets. 

  • Aerospace and defense

  • Automotive industry

  • Power generation

  • Docks and marinas

  • Fountains and aquariums

  • Cooling towers

  • Manufacturing

  • Food processing

  • Beverage industry

  • Metals and mining

  • Plating plants

  • Pulp and paper industry

  • Car washes

 

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