DIFFERENCE IN GLASS FIBRE.

The two methods most generally used to produce glass fiber blanket material for acoustic and thermal insulation are described, and the differences between the products are indicated. The Rotary Process is the procedure whereby glass is allowed to run into a hollow spinner which has a series of small holes drilled around its perimeter. The glass is thrown out by centripetal force to form the fibers, which are then sprayed with binder in the 'felting chamber'. The fibers are then collected by suction on a conveyor belt to form an uncured blanket: this blanket is then passed through the curing oven. In the Flame Attenuation Process, glass marbles are fed into small heated pots where the marble melts to form the molten glass. A series of platinum bushes is installed in the base of the pot, through which the molten glass is drawn to form filaments. The filaments are drawn down by rollers (thus enabling a very fine control to be kept over the fiber diameter) and attenuated into long, even fibers by gas jet burners. These fibers are then sprayed with binder, collected on a moving belt and cured to the desired density and thickness. Although more expensive then the Rotary process, the Flame Attenuation Process produces a blanket with a higher 'uniformity' of material throughout the blanket, and the material has very good resilience. Thus, the material can be folded and deformed in an installation operation without affecting its performance. When the deforming force is removed, the material will return immediately to its original shape. The material also provides superior thermal insulation. Some considerations leading to a choice of glass fiber for sound insulation are also given.