Quick answer: Polishing Borofloat 33 covers Borofloat 33 (CTE 3.25 x 10^-6 /K, 350 nm – 2.0 um); Polishing to flatness to lambda/4 per 25 mm. Prototypes ship in 5-10 working days.
polishing borofloat 33 is a materials problem before it is a machining problem. Borofloat 33 has float-glass flatness off the line and a Knoop hardness of 480 kg/mm2, so the polishing recipe – feeds, coolant, tooling – differs from what works on ordinary float glass. The line runs pitch and polyurethane pad polishers with cerium oxide slurry and holds flatness to lambda/4 per 25 mm.
Key parameters
| 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 | Polishing |
| Working tolerance | flatness to lambda/4 per 25 mm |
| Minimum feature | Ra below 1 nm |
| Surface finish | scratch-dig 40/20 to 20/10 |
| Thickness window | 0.2 – 50 mm |
| Edge condition | polished bevels available |
| RFQ inputs | PDF/DXF/STEP drawing, quantity brackets, surface and edge spec |
Design guidance
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: steep aspect parts and deep pockets polish unevenly; those faces are specified as fine-ground.
- 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.
Process window
Polishing earns its place through optical-grade faces with certified scratch-dig and interferometer-verified flatness. Its boundary condition – steep aspect parts and deep pockets polish unevenly; those faces are specified as fine-ground – is the first thing our DFM review checks.
Beyond this page, Borofloat 33 routinely runs through dicing, cnc machining, sandblasting, lapping in our shop – most real parts combine two or three of these steps.
Typical applications
The recurring buyers of polishing borofloat 33: mems devices (cap wafers, TGV substrates, motion-sensor lids); microfluidic devices (chips, manifolds, via plates, bonded stacks); led packaging (groove covers, phosphor carriers, package windows). Background reading on the underlying material science: SCHOTT BOROFLOAT product page.
Dimensions still moving? Configure this part live in the 3D + 2D builder below, or open the full custom glass machining 3D + 2D builder to start from a blank canvas.
For adjacent specifications, see optical polishing capability, Borofloat 33 selection guide, ultra-thin glass materials.
Buyer questions, answered
What equipment runs the polishing work?
Pitch and polyurethane pad polishers with cerium oxide slurry.
Is there a minimum order for polishing borofloat 33?
No. Single prototypes are accepted, and pricing steps down at 10, 100 and 1,000 pieces.
How fast can prototypes ship?
Machined prototypes ship in 5 – 10 working days. Coated or bonded parts add 1 – 2 weeks depending on queue slots.
What files do you need for a quote?
A dimensioned PDF plus DXF or STEP geometry. If only a sketch exists, our drawing review service formalizes it before quoting.
Do parts ship with inspection data?
Dimensional reports, surface certificates and material certs per melt are available; specify the level on the RFQ.
Specifications on this page were last reviewed by our engineering team in September 2026.