How small of a micro feature can be molded on a medical silicone part?

Question: How small of a micro feature can be molded on a medical silicone part?

Answer: Silicone feature size is limited by the geometry, tooling, and process. Silicone will replicate surface finish features with less than 0.0005 inches in size. Features larger than 0.005 inch can often be manufactured with some considerations. Part geometries such as undercuts, large L/D pins and bosses can cause challenges in demolding, maintaining tool integrity, and forming full features without bubbles.

Shrink in micro parts is often not as much of an issue compared to larger parts since 2% on 0.005 inches is pretty small compared to 2% on a 3” part. Other issues may be magnified such as the difficulty in part removal from a mold, core deflection, and mismatch. Large undercuts in parts made with a high durometer and low tear strength material tend to tear more easily during removal. Large L/D parts holes (made by pins) may deflect during molding causing tool damage and/or features to be irregular. For perspective take a caliper or micrometer and set it to 0.005 inches. Simple features that are smaller than 0.005 inches may be possible but they are inherently difficult.

This entry was posted in General Silicone on by .

About Matt

Matt is a project engineer at Albright Technologies, Inc. After interning for two years and earning a Bachelors of Science in Mechanical Engineering from Western New England College Class of 2009, Matt joined Albright Technologies full time.

  • Alan Frechette

    Interesting reading. Well done Matt.

  • Donna Bibber

    The smallest features we molded were 3 microns in diameter, 3 microns deep. This was done on a silicon wafer and silicone injection molded. 84 Million features across a microscope slide sized part. It’s really important to choose a very good tensile strength material, however to release this much surface area from the mold. If I can help you with a specific application, please drop a line. Thanks.