Lapping Borosilicate Glass – Borosilicate Glass (CTE 3.3 x 10^-6 /K, 360 nm – 2.0 um); Lapping to flatness 1 – 3 um. No minimum order; DFM review included with every RFQ.
The combination of Borosilicate Glass and Lapping comes up constantly in RFQs for a reason – the material offers thermal shock resistance, and Lapping is the right way to get accurate geometry into it. Expect flatness 1 – 3 um and Ra 0.2 – 0.6 um matte.
The numbers
| 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 | Lapping |
| Working tolerance | flatness 1 – 3 um |
| Minimum feature | thickness +/-0.003 mm |
| Surface finish | Ra 0.2 – 0.6 um matte |
| Thickness window | 0.2 – 40 mm |
| Edge condition | not applicable |
| RFQ inputs | PDF/DXF/STEP drawing, quantity brackets, surface and edge spec |
Design guidance
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: lapped faces are translucent-matte; optical clarity requires a subsequent polish.
- 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.
Capabilities and limits
The core strength of Lapping is restoring flatness and parallelism on plates and repairing bowed stock. The honest limit: lapped faces are translucent-matte; optical clarity requires a subsequent polish. Both belong on the drawing before quoting, not after.
One material, many routes: on Borosilicate Glass we also quote drilling, edge grinding, polishing, laser cutting, and multi-step drawings are the norm rather than the exception.
Where these parts end up
Orders for lapping borosilicate glass cluster in 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.
Engineers scoping this work usually also review glass sandblasting, material selection guide, holes and edges design guide.
Common questions
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 lapping hold?
Flatness 1 – 3 um with minimum features of thickness +/-0.003 mm. Lapped faces are translucent-matte; optical clarity requires a subsequent polish.
Specifications on this page were last reviewed by our engineering team in July 2026.