What are the processing techniques for optical blanks

The processing technology of optical blanks mainly includes two core steps: blank forming and milling (rough grinding), which lay the foundation for subsequent precision grinding, polishing and other processes. ‌

The rough forming process aims to transform optical glass into a rough shape that is close to the final shape, in order to improve material utilization and processing efficiency. The main methods include:

Hot pressing method (secondary forming): Optical glass is heated and softened before being pressed into shape, which is suitable for large-sized parts, but the process is complex and the material utilization rate is relatively low. ‌

Droplet forming method (one-time forming): By continuous melting and drip control, the blank is directly formed, which has the advantages of high productivity and small processing allowance, but the applicable range of parts is limited (such as diameter 10-20mm). ‌

The milling and grinding process (usually referring to rough grinding) is used to remove the blank residue and initially form a spherical shape, mainly including:

Bulk abrasive processing: Using abrasive formed by mixing diamond sand with water, rough grinding of glass workpieces is carried out on a grinding disc. Different particle sizes of abrasive are selected according to the arc height (such as using abrasive coarser than 180 # when the arc height is greater than 1mm). ‌

Fixed abrasive processing: Mechanical crushing and removal of glass surfaces using pointed hard abrasive particles, with hydrolysis being a secondary factor. Spherical forming is often achieved using the Fan Cheng method (washing machining). ‌