A study of thermal cutting of glass

Thermal stresses due to a hot-air jet impinging on a glass sheet can be use d to stably initiate and attract a crack toward the jet axis. Relative moti on between the jet and glass sheet then can be used to cut the glass sheet, This paper presents a theoretical and experimental study of this process f or straight cuts. The model consists of sequentially coupled thermal and st ress analyses for different cutting velocities. The stress field is used to compute stress-intensity factors for different assumed positions of a crac k behind the moving air jet. The minimum air temperature for cutting and th e stand-off distance of the crack behind the nozzle increase as the cutting velocity increases, The various process and material parameters that contr ol the process-including cutting speed, air temperature, and sheet thicknes s-are reduced to dimensionless numbers. Theoretical results, presented as a map in the space of these dimensionless numbers, describe the conditions u nder which cutting is possible. An experimental cutting apparatus has been constructed and used to validate the heat-transfer analyses, Cutting experi ments on this apparatus are in good agreement with the model.