CNC Machining Optical Glass: Optical Glass (CTE 7.1 x 10^-6 /K, 350 nm – 2.0 um); CNC Machining to +/-0.01 mm positional. Single-piece prototypes to production volumes, quoted from your drawing.
cnc machining optical glass is a materials problem before it is a machining problem. Optical Glass has certified refractive index and dispersion and a Knoop hardness of 610 kg/mm2, so the cnc machining recipe – feeds, coolant, tooling – differs from what works on ordinary float glass. The line runs 4-axis machining centers with diamond tooling and through-spindle coolant and holds +/-0.01 mm positional.
Key parameters
| Material | Optical Glass (N-BK7, H-K9L and filter glass sets) |
|---|---|
| Thermal expansion (CTE) | 7.1 x 10^-6 /K |
| Service temperature | 400 C (Tg 557 C) |
| Transmission range | 350 nm – 2.0 um |
| Density | 2.51 g/cm3 |
| Knoop hardness | 610 kg/mm2 |
| Refractive index | 1.5168 @ 587 nm |
| Stock thickness | 0.30 – 50 mm |
| Maximum blank size | 300 mm diameter |
| Process | CNC Machining |
| Working tolerance | +/-0.01 mm positional |
| Minimum feature | 0.4 mm slot width |
| Surface finish | Ra 0.4 um ground, optional polish |
| Thickness window | 0.5 – 50 mm |
| Edge condition | chamfered 0.1 – 0.5 mm as standard |
| RFQ inputs | PDF/DXF/STEP drawing, quantity brackets, surface and edge spec |
Design guidance
The shop-floor rules that matter here:
- Material note: index-certified blanks must be oriented and serialized through the shop to keep melt traceability.
- Process boundary: internal corners carry a minimum radius equal to the smallest practical tool, typically R0.5 mm.
- Over-specification is the quiet budget killer: a 20/10 scratch-dig face costs roughly three times an 80/50 face, so grade each surface individually.
The full rules live in our tolerance design guide and holes and edges design guide.
Manufacturing capability
The core strength of CNC Machining is complex 3D geometry – pockets, steps, counterbores and compound edges in one setup. The honest limit: internal corners carry a minimum radius equal to the smallest practical tool, typically R0.5 mm. Both belong on the drawing before quoting, not after.
One material, many routes: on Optical Glass we also quote dicing, drilling, grinding, double-side polishing, and multi-step drawings are the norm rather than the exception.
Application context
cnc machining optical glass shows up across optical sensors (sensor windows, filter caps, lens covers); scientific instruments (reference flats, cells, prism mounts, stage inserts); ccd inspection equipment (CCD cover plates, reference grids, stage glass). Background reading on the underlying material science: RP Photonics: optical glass.
Dimensions still moving? Configure this part live in the 3D builder below, or open the full custom glass machining 3D builder to start from a blank canvas.
For adjacent specifications, see optical polishing capability, AR coating process, machining tolerance guide.
Buyer questions, answered
What tolerances are achievable on Optical Glass parts?
Ground features hold +/-0.01 mm and lapped thickness reaches +/-0.003 mm. Index-certified blanks must be oriented and serialized through the shop to keep melt traceability.
What thickness range do you stock for Optical Glass?
Standard stock spans 0.30 – 50 mm, with blanks up to 300 mm diameter. Other formats are sourced per order.
How does Optical Glass behave under heat?
CTE is 7.1 x 10^-6 /K and continuous service reaches 400 C (Tg 557 C), which is what drives its use where certified refractive index and dispersion matters.
What accuracy does cnc machining hold?
+/-0.01 mm positional with minimum features of 0.4 mm slot width. Internal corners carry a minimum radius equal to the smallest practical tool, typically R0.5 mm.
What equipment runs the cnc machining work?
4-axis machining centers with diamond tooling and through-spindle coolant.
Specifications on this page were last reviewed by our engineering team in July 2026.