MTD Micro Molding of Charlton, Massachusetts, molded an ophthalmic implant part made from EVA weighing just 0.00000313 grams. One of the keys, according to a recent post on the company’s Web site, was the ability to manufacture a gate that measured just 0.0018” x 0.0008”.
MTD used Sarix milling equipment, which is significantly slower than EDM (electrical discharge machining). “Sarix micro EDM capability enables us to make edge features that were not possible before, with finishes that are mirror-smooth and perfectly detailed corners, edges and surfaces,” writes Lindsay Mann of MTD.
The part, which was used for glaucoma treatment, was manufactured from 2010 to 2012 for an undisclosed customer.
There are other ways to measure successful molding in the miniature.
Micro molder Accumold of Ankeny, Iowa, notes that “a part measuring about an inch long can have many micro-sized features, a .004” (.1mm) thin wall section, a .008” (.20mm) diameter hole, etc.” Accumold makes its own micro injection molding machines.
In an interesting blog post on the Plastics Engineering Web site, Jan H. Schut reports that nano molding, first developed in Germany, is now commercial. Much of the focus is on creation of nano features on surfaces.
Accumold also notes that “micro-molding must be capable of producing thousands, millions, even billions of parts with the same precision.”