Flow behaviour of glass during extrusion

Infrared fibers

“…Extrusion is a well-established technique to produce axially symmetric rods with complex cross-sectional structure from bulk material, and has been used to produce rods from most IR glasses [132,133] and even crystalline materials [134]. As shown in Fig.…”

Extrusion of complex preforms for microstructured optical fibers

“…Our extrusion apparatus allows accurate control of ram force, ram speed and billet temperature over a wide range (10N-100 kN, 0.001-200 mm/min), which has allowed us to extend the billet extrusion technique to polymer [9], to exclude sources of human error via the automation of the extrusion process and to achieve high degree of reproducibility between preforms. We have also scaled up the billet and die diameter from 30 mm (as used previously) to 50 mm, which allows considerably larger number of transverse die features without reducing the feature size to unmanageable dimensions (<1 mm diameter) in terms of die machinability and flow restrictions [10].…”

“…It is not readily apparent how these die designs can be adapted and scaled to produce complex preforms. The existence of preform structure distortions relative to the die exit geometry [9,10] also mandates careful optimization and control of not only the die design but also the extrusion conditions.…”

Extruded single-mode high-index-core one-dimensional microstructured optical fiber with high index-contrast for highly nonlinear optical devices

“…The microstructured preform with multiple coaxial rings was fabricated using an extrusion technique. In earlier works on extrusion of glass, 9 it was established that when glass is extruded through a channel with circular cross-section, the flow behavior obeys the Hagen-Poiseuille law, i.e., the isothermal FIG. 1.…”