Fibre fabrication

Optical fibres made of glass are drawn from so-called preforms. A preform is a glass cylinder with the same properties as the fibre to be drawn, only the cross-sectional geometries are at least 100 times larger. These preforms are partially heated at one end. Gravity causes a glass drop to form as the viscosity of the glass material decreases. This drop loosens and pulls a glass thread behind it. With the parameters temperature, pulling speed and preform speed a constant diameter of the thread is set. If the glass of the preform is very pure, this glass thread, also called fibre, has an enormous mechanical strength. In order to maintain this strength, a protective layer of, for example, acrylate, polyimide or silicone is applied to the fibre before it is wound onto a reel. A fibre drawing tower can be up to 30 m high. The higher the tower is, the higher the production speed can be. This is especially important for fibre drawing plants for the production of telecommunication fibres.