Continuous filament glass fibre (assembled rovings)
Continuous Filament Glass Fibres contain silica sand, limestone, kaolin and dolomite and are produced using the same basic production process. Small amounts of specialty chemicals may also be added. Silica sand and limestone are extracted and milled before storage in the batchhouse.
Raw materials are blended and then melted in a furnace at approx. 1500° C to form molten glass with a uniform controlled viscosity.
The molten glass is then drawn through a multi-hole heat resistant precious tray called a bushing, which has up to a few thousands of precisely drilled openings through which the glass flows to form thin filaments. The filament's diameter ranges from 5 to 30 µm. They are treated by various chemical and physical processes called "sizing", which alter their properties and make them suitable for a wide range of specific reinforcement uses.
This sizing, for example, helps to protect the filament during weaving or braiding. It also determines the adherence of the glass fibre to different resins and therefore the quality and properties of the end-use application (e.g. if the end-use application is thermoplastics, the sizing makes it have an affinity for polymers). The type of sizing depends on the further processing (pultrusion, winding, moulding, weaving, etc.).
The process consumes thermal energy, typically natural gas, and electricity. Production and transport of electricity is representative of national electricity production, where each sit is located.