Medical Micro Molding

Medical micro molding is a highly specialized niche in the plastic injection molding industry. Medical devices from leading OEMs depend on micro-injection molded components as the miniaturize their technology, providing critical patient care in and outside the body. Micro-molding denotes plastic injection molded components with micron-sized features and extremely tight tolerances.

Medical micro molding validation

person with pipette in medical setting

Medical device components require process validation that typically far exceeds the requirements of other industries because of strict regulatory oversight. This strict process, coupled with the very tight tolerances required for these components, can make for a very challenging molding process. This is why a specialist such as Accumold is needed.

Three things to know about medical micro molding

Our cleanrooms meet ISO standards, 100k (ISO Class 8) and 10k (ISO Class 7), but that’s only a starting point. Engineers and OEM part designers working on their next medical project must be aware of three core aspects of the medical micro molding process before starting their next project.

1. Gates and ejection

As parts become smaller, requiring half-micron or micron tolerances, gate and ejection pin features take up a considerable percentage of part geometry—much more than in a small injection molded component. As designers consider the medical micro molding process they need to keep in mind how they will gate the part for molding and also how they will extract it from the mold.

2. Standard wall thickness and size doesn’t apply

Our medical ultra-thin and ultra-small micro molding process allows part designers and OEMs to stretch the generally accepted standards for wall thickness and part size. Our DFM engineers routinely mold components that aren’t possible according to resin supplier specifications. We often hear “oh, I didn’t know you could do that with plastic.”

3. Stretching Complexity

In the same way we stretch what resins can do at micro levels, we also stretch what’s possible in part complexity and intricate cavity design. We’ve discovered one reason complex projects are often abandoned is because medical device designers are unaware their microscopic molding requirements are possible. This reason alone is why it’s best to bring our DFM team in as your advisor as early as possible.

Medical micro molding materials

Common materials for medical micro molding are as follows.

You can see how these materials behave in our thin wall study.PEEK Polyether ether ketone - micro molding materials

  • PEEK
  • Polysulfones
  • ABS
  • PC
  • Co-Polyesters
  • PBT’s)(like Tritan)
  • LCP’s
  • Polyurethanes
  • More micro mold resins >



Although medical micro molding examples are numerous some common examples are:

  • Insert-molded battery connectors for implantable cardiac devices flexible.
  • Thin-wall polyurethane tips used in pacemaker and neurostimulator leads.
  • Micro-needle arrays for drug delivery and tissue biopsy.
  • Micro-optic tips used in next-generation OCT imaging systems.
  • Molded cannulae used in Ophthalmic surgery
  • Examples »

Accumold’s experience in medical

medical micro molding alongside other partsAccumold’s primary focus since our inception over 35 years ago has been molding small components with very tight tolerances. That’s all we do. In that time, we have learned new tooling and processing techniques to make medical micro molding and micro parts possible.


The biggest misconception about micro molding is the assumption it’s simply a smaller version of injection molding. The process is completely different which is why many injection molders have difficulty getting into true micro molding with micron tolerances.

We have a very large team with decades of experience molding microscopic challenging parts. All of our tooling and automation is designed, built, and maintained in-house 24/7 and our DFM engineers are ready to help on even your most challenging medical micro molding component.

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