MATERIAL SELECTION FOR MANUFACTURED GLASS PARTS

Glass Materials for Lighting and Optical Components

Material selection begins with the finished component: its shape, wall section, light path, operating temperature, mounting method and required secondary processing. China Lampoptics uses three practical material directions for most projects, then evaluates optical glass or fused silica when the optical prescription or thermal environment requires a more specialized route.

START WITH THE DUTY

Material Selection at a Glance

These are engineering starting points, not automatic substitutions. Final composition, forming method, tempering and inspection criteria are confirmed against the drawing and service conditions.

Material direction	Best starting point for	Main design value	Confirm before quotation
Borosilicate 3.3	Heat-exposed covers, sight or gauge parts, windows and selected lighting components	Low thermal expansion and good resistance to thermal shock and chemicals	Part geometry, temperature gradient, forming route and post-processing
Soda-Lime Glass	Pressed lamp shades, globes, covers and higher-volume decorative or protective parts	Economical forming, broad finish options and established tempering routes	Thermal duty, wall distribution, color or diffusion target and impact requirement
Aluminosilicate Glass	Thin protective covers and compact parts requiring a strengthening review	Chemical-strengthening potential and mechanical durability in suitable geometries	Exact grade, thickness, edge condition, strengthening depth and assembly load
Optical Glass	Molded lenses and optical elements with a defined prescription	Grade-specific refractive index, dispersion and spectral transmission	Glass code, n_d, V_d, wavelength range, surface and centration
Fused Silica	Special high-temperature, UV or optical lighting components	Very low thermal expansion and grade-dependent spectral performance	Fused silica grade, wavelength range, purity, temperature cycle and fabrication route

Reference values describe recognized material families or representative grades. The approved drawing, supplier certificate and process route govern the finished component.

THREE MAIN MATERIAL DIRECTIONS

Practical Choices for Most Projects

Borosilicate 3.3

For thermal stability and chemical durability

Borosilicate 3.3 is the preferred starting point when a component sees meaningful temperature change, a demanding cleaning environment or long-term chemical exposure. Its nominal linear expansion is about 3.3 × 10⁻⁶/K, substantially lower than conventional soda-lime glass.

Suitable projects can include heat-resistant lamp covers, sight glass, gauge glass, viewing windows and selected optical or lighting parts. Shape, wall thickness and temperature gradient still determine whether the intended forming and strengthening route is practical.

Specify: Temperature cycle, pressure or load, medium, dimensions and edge condition
Review: Pressed or fabricated route, annealing, drilling, coating and inspection

Soda-Lime Glass

For cost-effective pressed lighting glass

Soda-lime glass is often the practical choice for pressed lamp shades, globes, decorative covers and protective parts when the thermal requirement allows it. It supports clear, opal, frosted, ribbed and textured appearances and is well suited to repeat production.

A representative flat-glass reference has a density near 2.50 g/cm³ and a thermal expansion near 8.3 × 10⁻⁶/K. Final material and heat-treatment decisions depend on the actual molded geometry, wall distribution and service temperature.

Specify: Illuminated appearance, color, opening or fitter, temperature and annual quantity
Review: Mold design, wall flow, annealing, physical tempering and cosmetic limits

Aluminosilicate Glass

For strength-led compact components

Aluminosilicate glass is considered when a thinner protective component or compact assembly needs a more demanding mechanical review than standard soda-lime glass can provide. Selected grades can respond well to chemical strengthening and support deeper compression layers.

Because aluminosilicate covers several chemistries, there is no single universal property table. The grade, thickness, edge quality, strengthening recipe and mating structure must be evaluated together before performance is stated.

Specify: Thickness envelope, impact or bending load, exposed edges and assembly method
Review: Grade availability, cutting, edge finishing, chemical strengthening and proof test

SPECIAL PROJECT ROUTES

Optical Glass and Fused Silica

These materials are selected when a lens prescription, transmission band or unusual thermal environment justifies a specialized route. They are not presented as default materials for every pressed lamp shade.

Optical Glass

Use optical glass for molded lenses and precision optical components when refractive index, Abbe number, spectral transmission, homogeneity and surface requirements form part of the drawing. The glass code must be selected with the optical design and manufacturing route.

Explore glass lens products →

Fused Silica

Consider fused silica for special high-temperature lighting, UV transmission or optical windows where very low thermal expansion and grade-specific spectral behavior are important. Purity, OH content, wavelength range and fabrication method are confirmed per project.

Explore custom glass windows →

OPTICAL MATERIAL PROPERTIES

Fused Silica Optical and Thermal Properties

Fused silica combines low thermal expansion with optical performance suited to selected UV, visible and infrared applications. These material references support lens design; finished-part transmission depends on the silica grade, wavelength, thickness and surface treatment.

Property	Reference value	How to use it
Visible internal transmittance	99.40% at 468 nm on a 10 mm sample	Material specification only; finished-part transmission depends on thickness, surfaces and coating
Refractive index	1.46345 at 486 nm	Confirm the exact grade and wavelength-dependent index before releasing an optical prescription
Density	2.20 g/cm³	Useful for preliminary mass and mounting estimates
Thermal expansion coefficient	5.8 × 10⁻⁷ K⁻¹	Use with the actual temperature cycle, holder material and assembly clearance
Strain / annealing / softening points	935 / 1029 / 1525 °C	Material-characterization references, not finished-component service-temperature ratings
OH content	<1 ppm	Confirm by grade or batch documentation when UV/IR performance depends on hydroxyl content
Spectral range reference	193–3000 nm	Transmission varies with silica grade, wavelength, thickness and surface treatment

Related optical products: fly-eye lenses, microlens arrays, aspherical lenses and TIR lenses.

DRAWING-BASED REVIEW

Material Is Only One Part of the Component

GeometryDiameter, height, wall, radii, opening, edge, thread or mounting interface.

Optical targetTransmission, diffusion, beam behavior, color, wavelength range and illuminated appearance.

Service dutyContinuous and transient temperature, thermal gradient, pressure, impact, chemicals and cleaning.

Process routePressing, molding, annealing, grinding, polishing, drilling, tempering, coating and inspection.

MATERIAL FAQ

Questions Before Material Approval

Can one material replace another without changing the drawing?

Not automatically. Thermal expansion, viscosity, shrinkage, annealing, strengthening response and optical properties can change the tooling or finished dimensions. Any substitution needs a drawing and process review.

Which material is best for a hot lamp cover?

Borosilicate 3.3 is a common starting point, while fused silica may be considered for unusually high temperatures or special wavelengths. The actual choice depends on heat source, distance, ventilation, temperature gradient and mounting stress.

Is aluminosilicate always chemically strengthened?

No. Chemical strengthening is a separate process and its result depends on the exact glass grade, thickness, edge preparation and required depth of layer. The strengthening target must be defined for the finished part.

What should I send for a material recommendation?

Send the drawing or sample, operating temperature, light source or wavelength range, mounting method, required optical appearance, mechanical load, secondary processes and expected quantity.

DISCUSS A GLASS MATERIAL FOR YOUR COMPONENT