Overview of Fiberglass

Fabrication Of Fiberglass

Glass fiber is made of SiO2, which melting point is 1720°C. SiO2 is also the basic element of quartz, quartz is crystalline, and its SiO2 content is greater than or equal to 99% (when SiO2 is heated to 1200 ° C, and then cooled in the environment, it will crystallize into quartz). Glass is produced by varying the temperature and cooling rate. Crystallization can be prevented if pure SiO2 is heated to 1720°C and then rapidly cooled. Through continuous improvement and innovation, today's fiberglass manufacturers have combined this strategy of high temperature and rapid cooling with other steps, although the process is essentially the same as that developed in the 1930s, but with a much larger scale. The manufacturing process of glass fiber can be divided into five basic steps: batching, melting, fiberization, sizing and drying. 

Manufacturing Process of fiberglass 

Batching

During the initial stages of glass manufacturing, all ingredients must be accurately weighed and thoroughly mixed. Today, the batching process is automated through computerized weighing and closed material transport systems

 Melting

One pneumatic conveyor sends the batching to a heating furnace under temperature 1400 ° C for melting. Furnace has three parts. The first part is the ingredient receiving bin, where the ingredients are melted and homogenized, including the removal of air bubbles. The second part is a refiner with temperature 1370℃, where the molten glass flows for refining. The last part is the forehearth, generally there are 4-7 liners under the forehearth, which are used to extrude the molten glass into fibers. Large furnaces often have multiple channels, each with its own forehearth. 

Fiberization

The fiberization of glass fibers involves extrusion and drawing. During extrusion, molten glass flows through a bushing made of corrosion-resistant platinum alloy. The bushing is electronically heated, and the heating temperature needs to be precisely controlled to maintain a constant glass viscosity. As the glass streams exit the bushings under temperature 1204℃, they are cooled with water jets. Drawing is the process of passing the extruded molten glass stream through a drawing machine and mechanically drawing it into a fiber. The diameter of the single fiber of glass fiber ranges from 4 um to 34 um, which is equivalent to 1/20-1/5 of a hair, each bundle of fiber strands is composed of hundreds or thousands of monofilaments. 

Sizing

In the process of fiberglass drawing, there wil be friction between fiber and concentrator. To protect the glass fiber, will make a speical treatment with sizing.

Effection of sizing: effectively lubricate the surface of the glass fiber, integrate hundreds or even thousands of glass fiber monofilaments into a bundle, improve the surface state of the glass fiber, provide the properties required for further processing and applications, Good compatibility and interfacial chemical adsorption properties. 

Classification of sizing: paraffin, siliane, starch 

Drying

Make glass fiber drying through equipment. Since the glass fiber will be through water cooling and sizing, the glass fiber strand will contain a certain amount of moisture, which is about 8%-14% of total weight, which will adversely affect the further processing.