Molding ophthalmic lenses is a complex process which requires the combination of
(a) significant experience in machining precision molds / inserts
(b) extensive expertise in polymerization processes, and
(c) combining both of the above with successful ophthalmic lens designs in a controlled and repeatable molding process.

Non-ferrous metals: Most molds / inserts are manufactured in non-ferrous metals. These typically include electroless-nickel plated surfaces, aluminum, various copper alloys (including certain grades of brass) etc.
The following table may provide helpful machining guidelines.

Click to enlarge

Electroless Nickel is laid down by a chemical reduction process, and the thickness of the material used can therefore be calculated and controlled in manufacturing the blank which will then be diamond turned.

The surface plating result is completely uniform, which suits irregular shapes such as aspheric lenses with complex optics, because there is no excess build-up at edges or corners.

It has excellent corrosion resistance and high “hardness” ratings, with an inherent lubricity, unlike electrolytic nickel. Electroless nickel is less porous, with the benefit of longer tool life.

The tensile strength exceeds 700 MPa and so electroless nickel can take quite considerable use without damage.

Electroless Nickel is laid down by a chemical reduction process, and the thickness of the material used can therefore be calculated and controlled in manufacturing the blank which will then be diamond turned.

The surface plating result is completely uniform, which suits irregular shapes such as aspheric lenses with complex optics, because there is no excess build-up at edges or corners.

It has excellent corrosion resistance and high “hardness” ratings, with an inherent lubricity, unlike electrolytic nickel. Electroless nickel is less porous, with the benefit of longer tool life.

The tensile strength exceeds 700 MPa and so electroless nickel can take quite considerable use without damage.

Ferrous metals, such as stainless steels, are less commonly used because they have a tendency to “tear” when being diamond turned. Therefore it becomes necessary to “rough-out” the part, then go to a hardening process, followed by a finishing-cut of the hardened surface using special tooling. Even then, with “tearing” minimized, it is still necessary to polish the part.

Attempts to go from roughing to a finished part via extensive polishing generally results in significant loss of “form” (shape) by the time an acceptable “surface finish” is achieved.

Every producer of molded Contact Lenses and molded IOLs worldwide uses OPTOFORM and / or NANOFORM ultra-precision machine systems.

Contact us for further information or assistance with mold insert materials and manufacturing.