Robax · heat-treated state · default condition
Robax Annealed Glass
Properties of the Annealed Glass condition, compared with the other Robax tempers.
Standard choice for fireplace and stove viewing windows, oven doors and furnace sight glasses where clear vision and thermal-shock resistance are needed.
What is Robax Annealed Glass?
Robax Annealed Glass is Robax heat treated to Annealed Glass — standard choice for fireplace and stove viewing windows, oven doors and furnace sight glasses where clear vision and thermal-shock resistance are needed. Robax Annealed Glass has a tensile strength of 35 MPa (5.08 ksi), weaker than 80% of glass grades. Elongation at break is 0% and the elastic modulus is 92 GPa (13.3 Msi). Robax Annealed Glass has a density of 2.55 g/cm³ (0.0921 lb/in³), lighter than 63% of glass grades.
Advantages
- Stiff — 92 GPa (13.3 Msi), better than 76% of glass grades
- Low embodied carbon — 2.2 kg CO₂/kg, better than 76% of glass grades
- Tough — resists crack growth — 0.9 MPa·√m (0.819 ksi·√in), better than 75% of glass grades
Robax Annealed Glass properties
Typical room-temperature values for Robax Annealed Glass — 4 properties are specific to this condition; the rest are grade-level values shared by every Robax temper. Each bar shows where the value sits among the glass grades in FabDigit's library — further right is higher.
Physical4
Robax Annealed Glass has a density of 2.55 g/cm³ (0.0921 lb/in³), lighter than 63% of glass grades.
Mechanical12
Robax Annealed Glass has a tensile strength of 35 MPa (5.08 ksi), weaker than 80% of glass grades. Elongation at break is 0% and the elastic modulus is 92 GPa (13.3 Msi).
Thermal5
Robax Annealed Glass is rated for continuous service to 700°C (1,292 °F). It conducts heat at 1.6 W/m·K (0.924 BTU/hr·ft·°F), better than 61% of glass grades. Thermal expansion is 0.1 µm/m·K (0.0556 µin/in·°F).
Electrical5
Robax Annealed Glass is an electrical insulator with a dielectric strength of 25 kV/mm (635 V/mil) and a resistivity of 1×10¹¹ Ω·m.
Chemical & Environmental2
Corrosion resistance is excellent (85/100), better than 62% of glass grades.
Sustainability4
Producing a kilogram of Robax Annealed Glass takes about 30 MJ of energy and emits 2.2 kg of CO₂ — less than 80% of glass grades. Typical recycled content is 0%.
Manufacturability3
Robax Annealed Glass's machinability is not recommended (6/100, worse than 85% of glass grades).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other Robax tempers and conditions
Robax is also supplied in 2 other conditions. The full side-by-side table is on the Robax overview.
- Annealed GlassDefaultStandard choice for fireplace and stove viewing windows, oven doors and furnace sight glasses where clear vision and thermal-shock resistance are needed.4 properties
Working with Robax Annealed Glass
Is Robax easy to machine?
Diamond grinding, water-jet or CO2/fiber laser cutting only; no scoring-and-snapping like soda-lime, and edges must be seamed/ground to remove flaws.
Can Robax be welded?
Not weldable; joined mechanically with gaskets or with high-temperature silicone/ceramic adhesives and rope seals.
Can Robax be formed, bent or molded?
Supplied as flat or roller-formed curved panels ceramized at the factory; end users cannot re-form or temper it — near-zero CTE means it is not (and need not be) thermally toughened.
What surface finishes work on Robax?
Screen-printed ceramic decoration, anti-reflective or IR-reflective sputtered coatings, and fine polishing are all possible; avoid HF-based cleaners and abrasive pads on coated faces.
Robax chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Al2O3 | 17 – 21 | 19 |
| Li2Oforms β-quartz solid solution → near-zero CTE | 3 – 4.5 | 3.7 |
| MgO | 0.5 – 2 | 1 |
| ZnO | 0.5 – 2.5 | 1.5 |
| TiO2nucleating agent | 1.5 – 3 | 2.3 |
| ZrO2nucleating agent | 1 – 2.5 | 1.8 |
| Na2O+K2Oresidual alkalis | 0.2 – 1.5 | 0.8 |
| BaO | 0 – 2 | 0.8 |
| fining agents (SnO2/As2O3-free modern ba | 0 – 1 | 0.3 |
| SiO2network former | ≥ 63 (balance) | — |
Robax Annealed Glass — frequently asked
What is Robax Annealed Glass used for?
Robax Annealed Glass is typically used for fireplace and stove door panels, cooktop panels, wood and pellet stove viewing windows, furnace and kiln sight glasses, commercial and pizza oven windows and gas fire viewing panels. In short: transparent fireproof ceramic.
What is the tensile strength of Robax Annealed Glass?
Robax Annealed Glass has a typical tensile strength of 35 MPa (5.08 ksi) — weaker than 80% of glass grades. Strength varies by condition: see the 3 listed tempers.
Is Robax Annealed Glass easy to machine?
Not especially — machinability is rated not recommended (6/100, worse than 85% of glass grades). Diamond grinding, water-jet or CO2/fiber laser cutting only; no scoring-and-snapping like soda-lime, and edges must be seamed/ground to remove flaws.
Can Robax Annealed Glass be welded?
Not weldable; joined mechanically with gaskets or with high-temperature silicone/ceramic adhesives and rope seals.
What surface finishes work on Robax Annealed Glass?
Screen-printed ceramic decoration, anti-reflective or IR-reflective sputtered coatings, and fine polishing are all possible; avoid HF-based cleaners and abrasive pads on coated faces.
Can Robax Annealed Glass be formed, bent or molded?
Supplied as flat or roller-formed curved panels ceramized at the factory; end users cannot re-form or temper it — near-zero CTE means it is not (and need not be) thermally toughened.
What is the maximum service temperature of Robax Annealed Glass?
Robax Annealed Glass is rated for continuous use to about 700°C (1,292 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in Robax Annealed Glass?
Yes — Robax Annealed Glass is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- ROBAX transparent glass-ceramic — technical data — SCHOTT AG (2023)
- NEOCERAM N-0 / N-11 glass-ceramic data sheet — Nippon Electric Glass (2021)
- ASM Engineered Materials Handbook Vol. 4 — Ceramics and Glasses (glass-ceramics chapter) — ASM International (1991)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.