Robax vs ZERODUR
Glass · grade comparison
Robax and ZERODUR are both glass grades. Robax is the stronger of the two: tensile strength 35 MPa (5.08 ksi) against 30 MPa (4.35 ksi) for ZERODUR, about 17% more. Robax runs hotter in service (700°C vs 500°C continuous). On the shop floor, ZERODUR machines more easily (poor vs not recommended).
RobaxChoose it when strength drives the design, or when the part sees heat.
ZERODURChoose it when the part is machined in volume.
Robax vs ZERODUR: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all glass grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
How to read these bars
- One bar per material. A full bar is the highest value among all glass grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Elastic (Young's) Modulus
Shear Modulus
Bulk Modulus
Poisson's Ratio
Tensile Strength (Ultimate)
Elongation at Break
Flexural Strength
Shear Strength
Hardness, Vickers
Hardness, Knoop
Hardness, Mohs
Same in both: Compressive Strength 500 MPa72.5 ksi · Fracture Toughness (K_IC) 0.9 MPa·√m0.82 ksi·√in
Physical
Density and transition temperatures.
Density
Refractive Index
Same in both: Light Transmission 88% · Porosity 0%
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Min Service Temperature
Electrical
Conductivity and insulation.
Electrical Resistivity
Dielectric Strength
Dielectric Constant (1 MHz)
Dissipation Factor (1 MHz)
Volume Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Corrosion Resistance 85 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Polishability
Sintering / Firing Temperature
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Same in both: Typical Recycled Content 0%
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Specific Stiffness (E / density)
Thermal Diffusivity
Strength versus weight
Yield strength against density for every glass grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
Manufacturing and finishing
| Capability | Robax | ZERODUR |
|---|---|---|
| Default condition | Annealed Glass | Annealed Glass |
| Relative cost | $$ Standard | $$ Standard |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Robax vs ZERODUR — frequently asked
Is Robax stronger than ZERODUR?
Yes. Robax has a typical tensile strength of 35 MPa (5.08 ksi) against 30 MPa (4.35 ksi) for ZERODUR — about 17% more.
Which is cheaper, Robax or ZERODUR?
Both sit in the same relative cost tier ($$, standard); the part price will be decided by machining time, tolerance and quantity rather than by the material.
Which is easier to machine, Robax or ZERODUR?
ZERODUR. Its machinability rates poor (20/100) against not recommended (6/100) for Robax.
Ready to make it?
Upload a CAD file and FabDigit prices the part in Robax and ZERODUR side by side — material, machining time, tolerance and finish in one quote. Certified material data ships with the order on request.
Typical handbook values for the conditions named above, normalised for comparison. Hardness on non-Brinell scales is converted approximately for charting only. Request certified data with your order for design-critical properties.