What is fiberglass, and what are its production principles?

In short: fiberglass is made by melting glass and drawing it into fibers a fraction of the thickness of a human hair. It combines the hardness and corrosion resistance of glass with the flexibility and weavability of natural fibers, making it the most widely used and cost-effective reinforcing fiber material today.

 

You may not have seen it directly, but you've almost certainly used it-it's found in your phone case, your bathtub, wind turbine blades, and even the insulation layer in your walls.

 

I. What exactly is fiberglass?

 

The chemical essence of fiberglass is not fundamentally different from the glass bottles and windows we use every day. Its main component is silicon dioxide (SiO₂), combined with oxides such as aluminum oxide, calcium oxide, and boron oxide. The difference lies in its form: ordinary glass is blocky and brittle; while fiberglass, when drawn into extremely fine fibers with a diameter of only 3-24 micrometers, undergoes a qualitative change-it becomes bendable, weaveable, and can be composited with resin, while still retaining the advantages of glass such as high-temperature resistance, corrosion resistance, and electrical insulation.

 

A single fiberglass monofilament is approximately 1/20 to 1/5 the diameter of a human hair. Bundling and weaving these monofilaments yields various forms of fiberglass products, such as fiberglass cloth and fiberglass mat.

 

II. How is it made?

 

The mainstream manufacturing method is the tank furnace drawing process, which generally follows:

 

. Melting: Natural mineral raw materials such as quartz sand, limestone, and borosilicate are added to a tank furnace according to a specific ratio and melted into molten glass at a high temperature of approximately 1400°C.

 

. Drawing: The molten glass flows through a platinum alloy baffle plate at the bottom (with hundreds to thousands of perforations), flowing out under gravity and being stretched and cooled by a high-speed drawing machine, instantly solidifying into continuous fibers.

 

. Impregnation: The drawn fibers are immediately coated with an impregnating agent, which protects the fibers, increases softness, and improves compatibility with resins.

 

. Post-processing: Depending on the application, it is processed into products such as untwisted rovings, chopped strands, fiberglass cloth, and fiberglass mat.

 

The brilliance of this process lies in the fact that glass, a material that "breaks at the slightest touch," undergoes a significant reduction in internal defects after being transformed into micron-sized fibers. Consequently, its tensile strength far surpasses that of block glass-the tensile strength of a single fiberglass filament can reach 2000-4000 MPa, 2-3 times that of ordinary steel.

 

III. Why is fiberglass so popular?

 

Its core advantages can be summarized in six words: lightweight, strong, durable, and inexpensive.

 

Lightweight: Fiberglass has a density of approximately 2.5-2.6 g/cm³, lighter than aluminum (2.7) and less than one-third the density of steel (7.8).

Strong: Its tensile strength far exceeds that of steel. When combined with resin (i.e., "fiberglass/FRP"), its specific strength (strength/density ratio) completely surpasses that of traditional metals.

 

Durable: Corrosion-resistant, high-temperature resistant (operating temperature up to 250-280°C), and weather-resistant, it does not rust or rot.

Price: Compared to carbon fiber (approximately 100-200 RMB/kg), fiberglass costs only 6-15 RMB/kg, offering extremely high cost-effectiveness.

Furthermore, it possesses excellent electrical insulation, thermal insulation, low water absorption, and designability (performance can be controlled by adjusting fiber direction and layup method).

 

IV. Where is Fiberglass Used?

 

Its applications are very broad. Here are a few of the most common:

 

3C Product Casings: Some laptop and tablet casings use fiberglass-reinforced composite materials, which are stronger than pure plastic and lighter than metal.

 

Construction: Fiberglass reinforced cement (GRC), the base material for waterproof membranes, and wall insulation layers (fiberglass wool).

 

Transportation: Fiberglass is widely used in car bumpers, truck fairings, and ship hulls.

 

Sports: Entry-level fishing rods, skis, and badminton rackets often use fiberglass as their base material.

 

Summary

 

The essence of fiberglass is that the "fiber-drawing" process transforms glass from a "fragile" material into a "flexible reinforcing material."