The roughing wheel is used for:

• A. Removing initial material.
• B. Final polishing.
• C. Beveling the edge.
• D. Applying protective film.

Answer: (A)

Roughing wheels are used for removing material quickly to shape the workpiece. In ophthalmic lens fabrication, they provide a coarse, high-removal-step that gets the blank down to the near-final contour without spending time on fine detail. After roughing, a finishing wheel with a finer grit takes over to smooth the surface and achieve the optical polish. Using the roughing wheel for final polishing would leave a rough surface and possible scratches, and beveling or applying film are separate operations not served by this coarse step. So the roughing wheel’s job is to remove initial material to establish the basic shape.