Fiberglass Drawing Technology: Direct‑melt and Crucible Process Comparison

Fiberglass drawing technology is the core process of glass fiber production. It refers to manufacturing continuous glass filaments by drawing high-temperature molten glass through precision bushings. At present, more than 90% of fiberglass products worldwide are produced through mature and efficient drawing technologies.

There are two mainstream fiberglass forming processes in the industry: the one-step direct-melt bushing process and the traditional two-step crucible drawing process.

Direct-melt Bushing Process (One-step Forming)

Raw materials including pyrophyllite and silica sand are directly melted into uniform molten glass inside the industrial furnace. After flowing steadily through the special forehearth passage, the molten glass passes through multi-hole bushings and is rapidly drawn into continuous glass filaments at a high speed.

This one-step production method features simple working procedures, stable fiber quality, energy saving and high efficiency. It fully adapts to large-scale, automated and standardized industrial production, and has become the dominant and internationally recognized mainstream fiberglass manufacturing technology.

Crucible Drawing Process (Two-step Forming)

The crucible drawing process is a traditional two-step forming technology. Firstly, raw glass materials are melted and made into solid glass marbles. In the second procedure, the glass marbles are remelted again for fiber drawing.

Compared with the direct-melt process, this technology has obvious disadvantages such as high energy consumption, low production efficiency and unstable fiber quality. Therefore, it has been basically eliminated by large professional fiberglass manufacturers. Currently, it is only reserved for producing a small amount of special and customized fiberglass products with unique compositions.