Grinding Borofloat 33 – Borofloat 33 (CTE 3.25 x 10^-6 /K, 350 nm – 2.0 um); Grinding to flatness to 5 um over 100 mm. No minimum order; DFM review included with every RFQ.
Ask any process engineer what makes borofloat 33 difficult and the answer is specific: float tin side must be tracked when parts see coating or bonding steps. Our grinding line is tooled around exactly that – rotary surface grinders and double-disc machines with diamond wheels – holding flatness to 5 um over 100 mm on parts from 0.3 – 60 mm thick.
Specification envelope
| 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 | Grinding |
| Working tolerance | flatness to 5 um over 100 mm |
| Minimum feature | thickness to +/-0.005 mm |
| Surface finish | Ra 0.2 – 0.8 um |
| Thickness window | 0.3 – 60 mm |
| Edge condition | ground perimeter, squareness 0.02 mm |
| RFQ inputs | PDF/DXF/STEP drawing, quantity brackets, surface and edge spec |
Manufacturing capability
The core strength of Grinding is bringing thickness, flatness and parallelism into calibrated tolerance before polish. The honest limit: subsurface damage of 5 – 15 um must be budgeted and removed by polishing on optical faces. Both belong on the drawing before quoting, not after.
One material, many routes: on Borofloat 33 we also quote edge grinding, coring, double-side polishing, polishing, and multi-step drawings are the norm rather than the exception.
Design guidance
Three items decide most of the cost and lead time on this work:
- Material note: float tin side must be tracked when parts see coating or bonding steps.
- Process boundary: subsurface damage of 5 – 15 um must be budgeted and removed by polishing on optical faces.
- 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.
Who orders this
Orders for grinding borofloat 33 cluster in machine vision (camera windows, ring-light diffusers, calibration plates); mems devices (cap wafers, TGV substrates, motion-sensor lids); microfluidic devices (chips, manifolds, via plates, bonded stacks). Background reading on the underlying material science: SCHOTT BOROFLOAT product page.
The fastest route to a quote is geometry: use the 3D builder below, draw a dimensioned 2D drawing from it, or open the site-wide custom glass machining 3D + 2D builder for fully custom parts.
Engineers scoping this work usually also review Borofloat 33 selection guide, precision glass grinding, custom FTO glass.
Buyer questions, answered
What equipment runs the grinding work?
Rotary surface grinders and double-disc machines with diamond wheels.
Is there a minimum order for grinding 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.
Specifications on this page were last reviewed by our engineering team in September 2026.