Micro Molding

Micro molding is the process of manufacturing extremely small plastic parts via injection molding. Though they have a wide range of applications, micro molded plastic parts are exceptionally useful for the medical industry, where they are used in surgical equipment and implantable devices. Micro molding is also frequently used in the manufacture of electronics devices, which continue to become simultaneously smaller and more powerful.

Micro molding is perhaps the most difficult variation of plastic injection molding. Injection molding polymers (the plastic materials) tend to have “large” molecules that are difficult to transform into such miniscule pieces. Common micro molded polymers include thermoplastics, thermosets, and elastomers. To effectively and efficiently produce micro molded parts, injection molding companies must have both the highly specialized equipment required and considerable materials knowledge.

The fine details on the underside of this key were produced via micro molding.

The fine details on the underside of this key were produced via micro molding.

In addition to unique nature of the molding polymers, injection molders must also contend with the miniscule scale of the actual molds themselves. At such small sizes—micro molded parts can be as small as a few thousandths of an inch in diameter and weigh less than a gram—even generally robust mold and tool materials like stainless steel become highly flexible and fragile.

Micro molding is not used only for very small “whole” parts—it can also be used to add “miniature” details and features on “normal” sized plastic parts. Thin wall sections, very small diameter holes, fine threads, and other features that would only be possible via complex, post-molding machining operations can be added with micro molding.

The key to success in micro molding is tight tolerances. With parts so small, even the smallest deviation from design specifications will result in an unusable final product. In “standard” injection molding, tolerances within a few hundredths of an inch are acceptable; in micro molding, such variances would often be larger than the part as a whole. Acceptable tolerances in micro molding are measured in micro- or nanometers.

Micro Molding Providers

  • Stack Plastics specializes in micro molding, utilizing state-of-the-art injection molding equipment and years of experience to produce high quality, high precision—and extremely small—plastic parts and components.
Photo credit: Napf | CC BY-SA 3.0, via Wikimedia Commons
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