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Through previous marketing surveys and discussions with many companies in 1984 and '85, it has become apparent that there is a growing need for a grinding machine capable of producing high quality, aspheric optical surfaces on various brittle materials that cannot be directly machined by single crystal diamond tools. Some of the materials of prime interest are ceramics and carbides, to be used as molds for plastic and glass lenses. Even though tool steel substrates with electroless nickel plating are being directly machined by single crystal diamond tools and used for injection molding of plastic lenses, the harder carbide and ceramic substrates have more desireable properties as molds for both plastic and glass lenses. Various applications of these lenses include use in: - Cameras and Photocopiers - Fiber Optic Connectors, and - Pick-up Heads for Compact Disc Players for both audio and read only memory (CD-ROM) applications.Upon closer evaluation of these applications, it is clear that a major portion of the lens mold market will be satisfied by the ability to grind aspheric surfaces up to a maximum diameter of 50mm. Also, to fulfill other requirements of these molds, a grinder must be capable of producing accurate alignment diameters and shoulders which are concentric and square to the optical axis of the aspheric surface. (see Figure 1.) This paper will discuss the design of a Grinding Attachment for a standard turning lathe, which is being used for fabrication of the lens molds previously described. It focuses on grinding of a silicon carbide mold. The following key areas will be discussed in detail: - Process Development a. grinding wheel selection b. wheel dressing c. wheel setting d. cutting parameters - Restrictions/Limitations - Accuracies Achieved a. form error b. surface finish
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