Method for making a microstructure in a glass or plastic substrate according to hot-forming technology and associated forming tool

A method of using a forming tool to make a microstructure in a glass or plastic body by hot-forming technology, said method comprising the steps of:

• a) providing the forming tool, said forming tool comprising a base body, an operative layer applied to a surface on one side of the base body and means for supplying or withdrawing air from another surface on another side of the base body opposite from the one side on which the operative layer is applied, said base body comprising, a porous base material with an open pore structure and said operative layer comprising a gas-impermeable material structured according to a negative of the microstructure to be produced by the forming tool in order to form depressions or grooves that extend through the operative layer to the base material with the open pore structure;
• b) pressing the operative layer of the forming tool structured according to the negative of the microstructure to be produced into a viscous glass or plastic substrate;
• c) during the pressing of step b), generating an under pressure that acts on the open pore structure of the base body in order to draw glass or plastic material of the viscous glass or plastic substrate into the operative layer of the forming tool, and thus help form the microstructure in the viscous glass or plastic substrate;
• d) after the microstructure has been formed in the substrate in step c), removing the forming tool from the viscous glass or plastic substrate;
• and
• e) during the removing of step d), generating an overpressure that acts on the open pore structure of the base body to assist in the removing.