A device may generate a multi-layer stack of sheets that may be adhered into a slab-shaped preform for thermal drawing. The sheets may include sublayers. Stacking the sub-layered sheets results in accumulation of layers in the final fabricated preform. The stacking process may use mechanical translation and conveyance to support placement of the sheets and fabrication of the stack.

A method for manufacturing a preform assembly may included extruding a film through an extrusion die and translating a preform assembly so that a current layer for the preform is stacked on top of a previous lawyer of the preform. The extrusion die may have various features such as multiple inputs with a single stream output. A roller and a cutter may also be used as part of the layer stacking. The method may also take place in a enclosure with environment or temperature controls.

The invention relates to a process for producing an extruded sulfur-crosslinkable rubber mixture, comprising the following process steps: A) producing a sulfur-crosslinkable rubber mixture by means of a mixer or providing a sulfur-crosslinkable rubber mixture, where the temperature of the sulfur-crosslinkable rubber mixture is less than 35 C., B) contactlessly adjusting the temperature of the sulfur-crosslinkable rubber mixture produced or provided in step A) to at least 40 C. in a temperature adjustment unit, C) measuring the temperature of the rubber mixture in the temperature adjustment unit and D) feeding the sulfur-crosslinkable rubber mixture that has been measured in step C) into an extrusion unit at a temperature of 35 C. or more and extruding the fed rubber mixture in the extrusion unit. The invention further relates to an apparatus for performing the process and to the use of the apparatus.