Quick answer: Edge Grinding Borofloat 33 covers Borofloat 33 (CTE 3.25 x 10^-6 /K, 350 nm – 2.0 um); Edge Grinding to chamfer +/-0.05 mm. Prototypes ship in 5-10 working days.
The combination of Borofloat 33 and Edge Grinding comes up constantly in RFQs for a reason – the material offers anodic bonding to silicon, and Edge Grinding is the right way to get accurate geometry into it. Expect chamfer +/-0.05 mm and ground C or R profile, polish option.
The numbers
| Material | Borofloat 33 (SCHOTT float production, wafer grade) |
|---|---|
| Thermal expansion (CTE) | 3.25 x 10^-6 /K |
| Service temperature | 450 C continuous |
| Transmission range | 350 nm – 2.0 um |
| Density | 2.23 g/cm3 |
| Knoop hardness | 480 kg/mm2 |
| Refractive index | 1.471 @ 587 nm |
| Stock thickness | 0.70 – 25.4 mm |
| Maximum blank size | 500 x 500 mm |
| Process | Edge Grinding |
| Working tolerance | chamfer +/-0.05 mm |
| Minimum feature | 0.1 mm chamfer leg |
| Surface finish | ground C or R profile, polish option |
| Thickness window | 0.1 – 25 mm |
| Edge condition | C-chamfer, R-round, pencil or OG profile |
| RFQ inputs | PDF/DXF/STEP drawing, quantity brackets, surface and edge spec |
Getting the drawing right
Before sending the RFQ, check these against your drawing:
- Material note: float tin side must be tracked when parts see coating or bonding steps.
- Process boundary: profiles below 0.1 mm leg length are lapped by hand and priced per edge.
- 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.
For the complete framework, see the tolerance design guide and the holes and edges design guide.
Process window
Edge Grinding earns its place through edge strength – a finished chamfer roughly doubles the bend strength of a cut edge. Its boundary condition – profiles below 0.1 mm leg length are lapped by hand and priced per edge – is the first thing our DFM review checks.
Beyond this page, Borofloat 33 routinely runs through double-side polishing, sandblasting, grinding, lapping in our shop – most real parts combine two or three of these steps.
Application context
The recurring buyers of edge grinding borofloat 33: optical sensors (sensor windows, filter caps, lens covers); microfluidic devices (chips, manifolds, via plates, bonded stacks); mems devices (cap wafers, TGV substrates, motion-sensor lids). Background reading on the underlying material science: SCHOTT BOROFLOAT product page.
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 4 inch Borofloat wafers, Borofloat 33 selection guide, optical glass options.
Common questions
What tolerances are achievable on Borofloat 33 parts?
Ground features hold +/-0.01 mm and lapped thickness reaches +/-0.003 mm. Float tin side must be tracked when parts see coating or bonding steps.
What thickness range do you stock for Borofloat 33?
Standard stock spans 0.70 – 25.4 mm, with blanks up to 500 x 500 mm. Other formats are sourced per order.
How does Borofloat 33 behave under heat?
CTE is 3.25 x 10^-6 /K and continuous service reaches 450 C continuous, which is what drives its use where float-glass flatness off the line matters.
What accuracy does edge grinding hold?
Chamfer +/-0.05 mm with minimum features of 0.1 mm chamfer leg. Profiles below 0.1 mm leg length are lapped by hand and priced per edge.
What equipment runs the edge grinding work?
CNC edge grinders with profiled diamond wheels.
Specifications on this page were last reviewed by our engineering team in July 2026.