Abstract: A furnace (2) has at least one furnace chamber (20) delimited by a wall (25); at least one opening (5) is provided in the wall (25). The opening is provided with at least one nozzle (50), configured to generate a sealing air flow. A glass semi-finished product (4) can be introduced into the furnace chamber.

Abstract: A furnace (2) has at least one furnace chamber (20) delimited by a wall (25); at least one opening (5) is provided in the wall (25). The opening is provided with at least one nozzle (50), configured to generate a sealing air flow. A glass semi-finished product (4) can be introduced into the furnace chamber.

Abstract: The invention locally deforms a flat surface of a substrate made of glass or a glass ceramic by applying heat exclusively within a locally limited region via the flat surface by laser radiation, a gas flame, infrared radiation, microwaves or a plasma discharge directed towards the flat surface of the substrate to soften the substrate at least on the flat surface within the locally limited region; applies a force acting on the softened flat surface within the locally limited region which deforms the softened surface of the substrate within the locally limited region; cools the substrate to obtain a set deformed surface within the locally limited region; and applies heat exclusively within the locally limited region via the flat surface of the substrate to produce a temperature and viscosity gradient inside the substrate laterally and orthogonal to the flat surface within the locally limited region.

Abstract: The invention relates to a method for locally deforming a flat surface of a substrate made of glass or a glass-ceramic, and to an operating element that can be produced with the method. The method is characterised by the following method steps: applying heat exclusively within a locally limited region via the surface of the substrate by means of laser radiation, gas flame, infrared radiation, electrical microwaves or plasma discharge directed towards the surface of the substrate, in such a way that the substrate is softened at least on the surface within the locally limited region; applying a force acting on the softened surface within the locally limited region, such that the softened surface of the substrate is deformed within the region; and cooling the substrate to obtain a surface that is deformed and set within the local region.