TECH TIPS
Understanding Glass
Strengthening Heat Treated
for Extra Strength
Heat strengthening of glass is achieved by increasing the temperature of the glass to a point slightly below the softening point of the material and then immediately and quickly quenching the glass-generally by blowing volumes of cooler air on the surfaces to cool suddenly while the interior of the glass is still hot and expanded.
The surfaces become compressed and the interior of the glass is still hot and expanded. The surfaces are in compression and interior mass is in tension. The glass will release the tension when the surface compression layer is penetrated.
Horizontal glass strengthening is accomplished by placing the glass parts on ceramic rollers in a furnace that heats both surfaces of the parts with the quenching occurring sequentially on polymer ringed wrapped rollers in the quench zone of the equipment.
Heat-Strengthened Lenses will Sustain High Heat Tolerances with less glass expansion and less stress within the glass to provide additional Shock Resistance Protection!
Annealed Lenses are the standard of the industry. This process allows the glass to cool very slowly once the glass is removed from the high heat furnaces. This slow cooling process allows the lens to expand and contract with less tension. The glass is strengthened by subjecting to high heat and then cooling.