MgF2 vs N-BK7
Glass · grade comparison
MgF2 and N-BK7 are both glass grades. N-BK7 is harder — 610 HV against 450 HV for MgF2 — which matters for wear surfaces and threads. N-BK7 is lighter (2.51 g/cm³ vs 3.18 g/cm³ for MgF2) and MgF2 is stiffer (138.5 GPa vs 82 GPa). On the shop floor, N-BK7 sits in a lower cost tier (standard, $$) than MgF2 (high, $$$$).
MgF2Choose it when the part sees heat.
N-BK7Choose it when surface hardness matters, or when weight is the constraint.
MgF2 vs N-BK7: 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
Compressive Strength
Flexural Strength
Fracture Toughness (K_IC)
Hardness, Vickers
Hardness, Knoop
Tensile Strength (Ultimate)
Elongation at Break
Shear Strength
Same in both: Hardness, Mohs 6
Physical
Density and transition temperatures.
Density
Melting Point (Solidus)
Refractive Index
Same in both: Light Transmission 92% · 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)
Same in both: Min Service Temperature -200°C-328 °F
Electrical
Conductivity and insulation.
Dielectric Constant (1 MHz)
Dielectric Strength
Same in both: Electrical Resistivity 1×10¹² Ω·m3.94×10¹⁹ µΩ·in · Volume Resistivity 1×10¹⁴ Ω·cm
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Polishability
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Typical Recycled Content
Common Calculations
Ratios derived from the values above.
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 | MgF2 | N-BK7 |
|---|---|---|
| Default condition | — | Annealed Glass |
| Relative cost | $$$$ High | $$ Standard |
| Min. machined wall | — | — |
| Best machined surface | — | — |
MgF2 vs N-BK7 — frequently asked
What is the difference between MgF2 and N-BK7?
MgF2 and N-BK7 are both glass grades. N-BK7 is harder — 610 HV against 450 HV for MgF2 — which matters for wear surfaces and threads. N-BK7 is lighter (2.51 g/cm³ vs 3.18 g/cm³ for MgF2) and MgF2 is stiffer (138.5 GPa vs 82 GPa).
Which is cheaper, MgF2 or N-BK7?
N-BK7 is the lower-cost material: it sits in the standard tier ($$) while MgF2 is high ($$$$). Part price depends far more on geometry, tolerance and quantity than on raw stock — upload a CAD file for a live quote.
Which is easier to machine, MgF2 or N-BK7?
MgF2, by a small margin. Both rate poor for machinability — 25/100 against 18/100 for N-BK7.
Ready to make it?
Upload a CAD file and FabDigit prices the part in MgF2 and N-BK7 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.