Flat Glass

Spang Power Electronics is a manufacturer of custom power equipment installed throughout the Flat Glass Industry. Spang’s expertise in power control and conversion has helped us become a global leader for the following applications.

Float / Tin Bath Roof Heating

Float / Tin Bath Roof Heating is one of the applications used to manufacture modern flat glass, also known as float glass, for architectural and automotive installations. Flat glass is a sheet of glass made by floating molten glass on a bed of molten metal, typically tin. This method gives the glass a very flat surface and uniform thickness.

Spang Power Electronics provides SCR Controllers, Transformers, and Power Systems to provide highly accurate controlled power to the resistive heating elements located in the roof of the furnace. The electric heat keeps the tin molten and controls the temperature of the flat glass.

Annealing / Tempering LEHR

After traveling through the Float / Tin Bath Roof Heating furnace, the flat glass enters the Annealing / Tempering LEHR. The LEHR is a temperature controlled kiln for annealing of the newly formed flat glass. The process gradually cools the molten glass to reduce mechanical stress and potential for cracking as it travels through the length of the kiln.

Spang Power Electronics provides SCR Controllers and Power Systems to provide highly accurate controlled power to the resistive heating elements located in the roof of the LEHR. Although the process is meant to cool the glass, the addition of heat is required in some sections of the kiln to maintain uniform temperature across the width of the sheet of glass.

Forming / Bending LEHR

The float glass manufacturing process produces flat glass in square or rectangular sheets. The flat glass must be then processed further for its specific use in architectural or automotive installations. For automotive, the glass must be cut to size and also formed / bent to the shape necessary to fit the window frame. In the Forming / Bending LEHR application, the flat glass which is cut to the necessary size and shape is placed on an installation specific pattern and then transitioned through the LEHR kiln for heating. As the glass heats it becomes soft and falls to the shape of the pattern.

Spang Power Electronics provides SCR Controllers and Power Systems to provide highly accurate controlled power to the resistive heating elements located in the LEHR. The electric heat provides the elevated temperatures necessary to soften the glass and complete the forming and bending process.

Melt Furnace Boosting

In modern flat glass manufacturing the batch is melted into molten glass by gas or oil as the primary heat source in the melting furnace. The majority of melting furnace installations do not use any electric heat. Some however will use electric heat which is injected by electrodes into the furnace from the bottom. The molten glass itself acts as the heating element conducting electricity between the bottom inserted electrodes (known as Joule heating).

Spang Power Electronics provides SCR Controllers, Transformers, and Power Systems to provide highly accurate controlled power to the electrodes of the melt furnace. The electric heat is added to improve the quality of the glass exiting the furnace as well as reduce changeover time when transitioning glass compositions. Boosting allows the furnace to flush faster thus reducing the changeover time.