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
The shop-floor rules that matter here:
- 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 sandblasting, cnc machining, dicing, grinding, 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 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 glass sandblasting, material selection guide, glass hole micromachining.
Common questions
What equipment runs the lapping work?
Cast-iron lap plates with boron carbide and alumina slurries.
Is there a minimum order for lapping borosilicate glass?
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.