Double-Side Polishing Borosilicate Glass – Borosilicate Glass (CTE 3.3 x 10^-6 /K, 360 nm – 2.0 um); Double-Side Polishing to TTV under 3 um. No minimum order; DFM review included with every RFQ.
Ask any process engineer what makes borosilicate glass difficult and the answer is specific: sheet stock carries more thickness variation than float wafer stock, so lapping is often the first step. Our double-side polishing line is tooled around exactly that – planetary double-side polishers with carrier plates – holding TTV under 3 um on parts from 0.1 – 10 mm thick.
Specification envelope
| Material | Borosilicate Glass (3.3 expansion group per ISO 3585) |
|---|---|
| Thermal expansion (CTE) | 3.3 x 10^-6 /K |
| Service temperature | 450 C continuous |
| Transmission range | 360 nm – 2.0 um |
| Density | 2.23 g/cm3 |
| Knoop hardness | 480 kg/mm2 |
| Refractive index | 1.473 @ 587 nm |
| Stock thickness | 0.50 – 30 mm |
| Maximum blank size | 600 x 400 mm |
| Process | Double-Side Polishing |
| Working tolerance | TTV under 3 um |
| Minimum feature | Ra below 0.5 nm both faces |
| Surface finish | 60/40 to 20/10 both faces |
| Thickness window | 0.1 – 10 mm |
| Edge condition | edge-rounded before DSP |
| RFQ inputs | PDF/DXF/STEP drawing, quantity brackets, surface and edge spec |
Process window
Double-Side Polishing earns its place through wafer-grade parallelism and sub-nanometer roughness on both faces simultaneously. Its boundary condition – parts must be round or near-round; strongly asymmetric outlines wedge in the carriers – is the first thing our DFM review checks.
Beyond this page, Borosilicate Glass routinely runs through lapping, grinding, polishing, ultrasonic machining in our shop – most real parts combine two or three of these steps.
Specification advice
Three items decide most of the cost and lead time on this work:
- Material note: sheet stock carries more thickness variation than float wafer stock, so lapping is often the first step.
- Process boundary: parts must be round or near-round; strongly asymmetric outlines wedge in the carriers.
- 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.
Who orders this
double-side polishing borosilicate glass shows up across medical diagnostics (flow cells, slides, microplate bottoms, cuvette windows); scientific instruments (reference flats, cells, prism mounts, stage inserts); laboratory instruments (cuvettes, sight glasses, stir-cell windows). Background reading on the underlying material science: ISO 3585 borosilicate glass 3.3.
The fastest route to a quote is geometry: use the 3D configurator below, or the site-wide custom glass machining 3D builder for fully custom parts.
Related reading on this site: glass sandblasting, material selection guide, AR coated glass materials.
Buyer questions, answered
What tolerances are achievable on Borosilicate Glass parts?
Ground features hold +/-0.01 mm and lapped thickness reaches +/-0.003 mm. Sheet stock carries more thickness variation than float wafer stock, so lapping is often the first step.
What thickness range do you stock for Borosilicate Glass?
Standard stock spans 0.50 – 30 mm, with blanks up to 600 x 400 mm. Other formats are sourced per order.
How does Borosilicate Glass behave under heat?
CTE is 3.3 x 10^-6 /K and continuous service reaches 450 C continuous, which is what drives its use where chemical durability matters.
What accuracy does double-side polishing hold?
TTV under 3 um with minimum features of Ra below 0.5 nm both faces. Parts must be round or near-round; strongly asymmetric outlines wedge in the carriers.
Specifications on this page were last reviewed by our engineering team in July 2026.