Fine Glass Machining

Selba machines two principal glass substrate families, each with distinct mechanical properties that require material-specific tooling parameters and cutting sequences. Borosilicate glass — including sodalime variants — is the standard substrate for encoder discs, calibration plates, photomask blanks, watch dial components, and general precision optical elements. Its moderate hardness and well-characterised fracture behaviour make it compatible with a broad range of cutting, profiling, chamfering, and drilling operations across standard thickness ranges. Quartz (fused silica) is significantly harder and more brittle than borosilicate, requiring slower cutting speeds, sharper diamond tooling, and more conservative material removal rates to achieve clean edge conditions and avoid sub-surface damage — but its exceptional thermal stability (≈0.55 ppm/°C) and UV transparency make it the required material for metrology, aerospace, deep-UV lithographic, and high-precision photonic applications. Across both substrate families, Selba processes substrates down to 0.1 mm thickness — a capability that demands fixturing, cutting, and finishing parameters developed specifically for the mechanical constraints of ultra-thin glass, using in-house designed machinery configured for this requirement.

Selba’s precision glass machining operations achieve micron-level dimensional accuracy on external profiles, edge geometries, and drilled features — tolerances that place glass machining at the boundary of what the material’s inherent brittleness permits and that require the controlled diamond cutting process and in-house designed fixturing that Selba has developed specifically for this purpose. Edge cutting accuracy is held at the micron level, enabling precise profile geometries, chamfer angles, and external dimensions to be produced repeatably across production batches without edge chipping, sub-surface cracking, or dimensional scatter that would compromise the mechanical or optical function of the finished component. Substrate thickness processable at Selba extends down to 0.1 mm — a dimension at which the glass substrate offers negligible resistance to out-of-plane machining forces, and where every process parameter, from diamond tool geometry and cutting speed through to coolant flow and workholding pressure, must be controlled specifically for the substrate thickness and material combination in question. At 0.1 mm, the interaction between the cutting tool and the substrate generates stress states that would fracture inadequately supported or improperly fixtured glass instantaneously — making the in-house design of Selba’s machining equipment, and the process knowledge embedded in its cutting parameters, the critical variables that make this thickness capability achievable in production rather than only in a laboratory setting. Chamfered edge profiles — produced to micron-level dimensional consistency using diamond tooling configured for the specific chamfer geometry required — are particularly important at thin substrate dimensions and large diameters, where the chamfer’s stress redistribution function must be geometrically precise to deliver the increase in peripheral rigidity and fracture resistance the application requires.

Precision glass machining and microfabrication serve a broad range of industries wherever glass substrates must be shaped, sized, or structured to tight dimensional and surface quality requirements. The Swiss watchmaking industry relies on precision glass machining for dial components and decorative elements, where dimensional accuracy and surface finish must meet the exacting standards of high-end horology. The optics and photonics industry uses glass machining for wafer resizing, dicing, and profiling of optical substrates for photonic component manufacturing, where cut edge quality and positional accuracy relative to the wafer’s optical structures are critical. The semiconductor and electronics industries require precision glass cutting, dicing, and substrate preparation across a range of photomask and encoder applications. Medical device manufacturers use machined glass mirror components in endoscopes, surgical microscopes, ophthalmic diagnostic instruments including fundus cameras and optical coherence tomography systems, and laser therapy delivery platforms. The precision surveying and geodetic instrumentation industry relies on machined glass graduation discs, reticles, and mirror elements in optical theodolites, total stations, and levelling systems. Industrial customers across automation, metrology, and scientific instrumentation sectors require precision glass cutting, resizing, and dicing services across a broad range of substrate materials and formats.