N-SF11
N-SF11 is a lead-free, high-index and high-dispersion flint optical glass used with crown glasses to form achromatic doublets and high-power lens elements.
Reference datasheet — N-SF11 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the N-SF11 condition
N-SF11 tempers and conditions
N-SF11 is supplied in 3 conditions, soft to hard. N-SF11 is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
N-SF11Default Lead- and arsenic-free heavy flint, standard (coarse) annealed… | Pick the standard coarse-annealed block or strip as the default lead- and arsenic-free high-index flint for achromatic cemented doublets and high-power lenses. | 45 | 0 | 470 HV | 0.75 W/m·K | |
N-SF11 fine/precision annealed | Choose the slow, precision-annealed material for high-accuracy imaging and interferometric optics: index homogeneity and internal stress birefringence are markedly better than coarse annealed stock. | 45 | 0 | 470 HV | 0.75 W/m·K | |
Classic lead-containing heavy flint | Use the classic lead-containing heavy flint only for legacy designs or when lower thermal expansion and more stable index versus temperature are required; about 50% PbO restricts it under RoHS. | 420 HV | 0.74 W/m·K |
What is N-SF11?
N-SF11 is a lead-free, high-index and high-dispersion flint optical glass used with crown glasses to form achromatic doublets and high-power lens elements. Engineers specify it where strong ray bending is needed in a compact element; it is supplied as strip, pressed blanks and fine-annealed lens blanks. Density is 3.2 g/cm³, elastic modulus 92 GPa and service temperature is capped at 400 °C. The polished surface is soft, scratches easily and has poor resistance to alkaline and phosphate cleaners; uncoated faces reflect about 7% each, so AR coating is standard, and leaded SF11 is the direct equivalent. N-SF11 has a density of 3.2 g/cm³ (0.116 lb/in³), heavier than 61% of glass grades. N-SF11 has a tensile strength of 45 MPa (6.53 ksi), weaker than 56% of glass grades. Elongation at break is 0% and the elastic modulus is 92 GPa (13.3 Msi).
What is N-SF11 used for?
- achromatic doublets
- camera lenses
- prisms
- optical instruments
Advantages
- Stiff — 92 GPa (13.3 Msi), better than 78% of glass grades
Limitations
- Poor heat conductor — 0.75 W/m·K (0.433 BTU/hr·ft·°F), worse than 92% of glass grades
N-SF11 properties
Typical room-temperature values for N-SF11-N-SF11; bars are the position among glass grades.
Physical4
N-SF11 has a density of 3.2 g/cm³ (0.116 lb/in³), heavier than 61% of glass grades.
Mechanical13
N-SF11 has a tensile strength of 45 MPa (6.53 ksi), weaker than 56% of glass grades. Elongation at break is 0% and the elastic modulus is 92 GPa (13.3 Msi).
Thermal5
N-SF11 is rated for continuous service to 400°C (752 °F). It conducts heat at 0.75 W/m·K (0.433 BTU/hr·ft·°F), worse than 92% of glass grades. Thermal expansion is 8.5 µm/m·K (4.72 µin/in·°F).
Electrical2
N-SF11 has an electrical resistivity of 1×10¹² Ω·m.
Chemical & Environmental2
Corrosion resistance is good (60/100), worse than 68% of glass grades.
Sustainability4
Producing a kilogram of N-SF11 takes about 60 MJ of energy and emits 4 kg of CO₂ — more than 58% of glass grades. Typical recycled content is 20%.
Manufacturability2
N-SF11's machinability is poor (15/100, worse than 54% 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.
Strength versus weight in the glass family
Yield strength against density for every glass grade FabDigit runs. N-SF11 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with N-SF11
Is N-SF11 easy to machine?
Not conventionally machinable: shape by diamond-wheel curve generating, precision lapping and pitch or polyurethane polishing. The material is relatively soft and scratches readily, so control abrasive grit size and pressure and support edges to prevent chipping.
Can N-SF11 be welded?
Not weldable; elements are held by optical cement (UV or thermal cure), optical contact, or mechanical mounts. Allow for cement-layer stress caused by CTE mismatch with crown glasses.
Can N-SF11 be formed, bent or molded?
Melted in crucible or continuous furnaces and formed into strip or pressed blanks, then annealed. The low softening point allows precision moulding of aspheres in graphite moulds under inert atmosphere.
N-SF11 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.
| Element | Spec limit (wt %) |
|---|---|
| TiO2main high-index/high-dispersion component, lead-free flint | — |
| Nb2O5raises refractive index and dispersion | — |
| BaOadjusts refractive index and melting behavior | — |
| Na2Oalkali oxide flux | — |
| K2Oalkali oxide flux | — |
| ZrO2improves chemical durability (small addition) | — |
| PbON-SF11 Pb- and As-free; legacy SF11 has about 50 wt% PbO | ≈ 0 |
| SiO2network former, balance; exact formulation proprietary | balance |
What surface finishes work on N-SF11?
AR-coat as soon as possible after polishing: single-surface reflection is about 7%, so an uncoated element loses roughly 14% across both faces. Clean with neutral solvents only and store dry.
Equivalent designations
Standards and trade names that resolve to N-SF11 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Also called
- SF11
How much does N-SF11 cost?
N-SF11 is a high-cost glass ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
N-SF11 — frequently asked
What is N-SF11 used for?
N-SF11 is typically used for achromatic doublets, camera lenses, prisms and optical instruments. In short: high index, high dispersion; lead-free SF11 replacement.
What is the tensile strength of N-SF11?
N-SF11 has a typical tensile strength of 45 MPa (6.53 ksi) — weaker than 56% of glass grades. Strength varies by condition: see the 3 listed tempers.
Is N-SF11 easy to machine?
Not especially — machinability is rated poor (15/100, worse than 54% of glass grades). Not conventionally machinable: shape by diamond-wheel curve generating, precision lapping and pitch or polyurethane polishing. The material is relatively soft and scratches readily, so control abrasive grit size and pressure and support edges to prevent chipping.
Can N-SF11 be welded?
Not weldable; elements are held by optical cement (UV or thermal cure), optical contact, or mechanical mounts. Allow for cement-layer stress caused by CTE mismatch with crown glasses.
What surface finishes work on N-SF11?
AR-coat as soon as possible after polishing: single-surface reflection is about 7%, so an uncoated element loses roughly 14% across both faces. Clean with neutral solvents only and store dry.
Can N-SF11 be formed, bent or molded?
Melted in crucible or continuous furnaces and formed into strip or pressed blanks, then annealed. The low softening point allows precision moulding of aspheres in graphite moulds under inert atmosphere.
What is the maximum service temperature of N-SF11?
N-SF11 is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does N-SF11 cost?
N-SF11 is a high-cost glass ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- N-SF11 Optical Glass Data Sheet — SCHOTT AG (2023)
- Optical Glass Collection Datasheets / TIE technical information — SCHOTT AG (2022)
- ASM Engineered Materials Handbook, Vol.4: Ceramics and Glasses — ASM International (1991)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.