Micromolded parts continue to get smaller and smaller and Plastics Engineering explores this topic f in their July/August issue entitled Getting to the Core of Micromolding.

Along with shrinking in size, parts are also getting more precise with details that nearly invisible.

According to SPE, “The smallest micro molded plastic part ever reported was a PET component weighing 0.00012 grams, which went into mass production in 1998 and was first reported in 2002 (molded by MTD Micromolding in Charlton, Mass., formerly Miniature Tool & Die). A POM micro bobbin weighing only 0.00015 g was reported by Sodick Inc., Kanagawa, Japan, molded in 2005 on a TR10EH2 micromolding machine.”

From late 2010 to 2012, MTD Micro Molding successfully molded an EVA ophthalmic part that weighs in at 0.00000313 grams. It is an ophthalmic implant for glaucoma treatment. This feat required MTD’s Sarix technology to make s precise gate needed for such a tiny part. The gate measured .0018” x .0008”. Even at 100X, the part is hardly visible. See the cover story for photos of the detailed, tiny steel inserts that make this microscopic geometry possible.

Weighing only 0.00000313 grams, an EVA ophthalmic implant molded by MTD may be (for now) the world’s smallest injection molded part (it’s the donut-shaped part shown in the magnified inset image).

Sarix milling equipment is well-known for its high quality and precision—however, EDM (electrical discharge machining) is 100 percent slower than traditional milling and Sarix is 100 percent slower than that. Sarix allows micro-machinists to create fine details with very little electrode wear. While graphite electrodes can machine sharp corners with .001- to .0015-inch corner radii, Sarix has such minimal wear that corners can measure at 5 microns (.0002 inches), with a tolerance resolution of .000004 inches and glass-like surface finish (Ra 0.05). 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. This capability gives our customers more flexibility for making more innovative, complex product designs. We brought this capability in house in June of 2009, making MTD the only mold making manufacturer in North America with this technology.


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