Arrangement of a furnace and of bulk material of glass particles as well as method for operating a furnace

A method for operating a furnace comprising a muffle, a pressing punch, a pressure, distance and/or speed sensor and a process controller for controlling a pressing process comprising,

• detecting, with the pressure, distance and/or speed sensor, at least a pressure, position and/or motion parameter of the pressing punch,
• controlling, with the process controller, the pressing process based on an output signal of the sensor,
• wherein, in the pressing process, the pressing punch acts on bulk material of glass particles and exerts pressure thereon,
• said bulk material of glass particles being introduced in a press channel of a muffle,
• wherein trigger criterion for the process controller is a change of at least a motion parameter of the pressing punch corresponding to the softening of the bulk material of glass particles, which change is detected by the sensor,
• wherein the sensor, below the softening temperature of the bulk material of glass particles, detects the thermal expansion of the muffle, a ram of the pressing punch, and the bulk material of glass particles, said thermal expansion counteracting the press force.