Heat Tempering

//Heat Tempering
Heat Tempering 2017-06-07T13:19:24-07:00

Heat Tempered soda-lime glass is about four times stronger than annealed glass and can handle approximately 2 to 3 times the thermal shock of annealed glass. Heat tempered glass effectively withstands bending, impact and rapid temperature change because the surface has been put into a state of compression. That process involves heating the glass at about 1200F in a tempering oven. In addition to improved strength, tempered glass is also safer because, if broken, it crumbles into small pieces instead of sharp shards, also known as dicing. Heat tempering can cause some optical distortion for high end optical applications such as display glass. Where optical change is not acceptable, chemical strengthening may be more suitable.  Heat tempered glass may be verified by performing a surface compression test or break pattern test for compliance.

JNS Glass, chemically strengthened glass, lighting lenses

Jns Glass, chemically strengthened glass, lighting lenses

Heat Tempering is appropriate where compliance to any of the following standards is required.

ANSI Z-26.1 – 1990 for Safety Glazing Materials used in Motor Vehicle Equipment.  DOT Certified.
ANSI Z-97.1 – 1984 (rev. 1994) for Safety Glazing Materials used in Buildings.
ASTM C-1036-90 Standard Specification for Flat Glass.
ASTM C-1048-90 Standard Specification for Heat Treated Glass

Minimum Thickness: 3 mm [0.118”] Maximum Thickness: 19 mm [0.75”] Minimum Size: 25.4 mm x 25.4 mm [1” x 1”] Maximum Size: 1219 mm x 3048 mm [48” x 120”] Glass Types:  Soda-lime based materials and borosilicate glass materials

Heat Strengthening

Heat Strengthening is appropriate for many applications and materials where a full temper is not possible or desired due to thickness, size, low thermal expansion rate of the base material, or other application requirements. This process does not produce a full “dicing” pattern when the glass is broken and will not meet the requirements of ANSI Z97.1 or CPSC 16CFR1201. Where appropriate, ASTM-C-1048 “Kind HS” may apply.