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Dale BuralliMarch 30, 20235 min read

When to Use Polymer Injection Molding for Medical Parts

Polymers have been a revolutionary advent in the medical industry. They offer an affordable, contaminant-resistant, lightweight, and precise solution to many medical supplies and devices, including medical components designed with polymer injection molding.

Polymers, and the polymer injection molding process, aren’t ideal for every medical device, however. Find out the advantages of injection molding and determine when it is the best choice for medical parts and equipment.

Why Are Polymers Preferred for Medical Use?

Polymers are the first choice for many medical applications for several reasons. There’s a wide range of different polymers suitable for various uses, and they all offer advantages in physical, chemical, and biological properties to meet the requirements of specific applications.

Most polymers integrate seamlessly with other materials, so they fit easily into medical devices comprised of different high-performance materials.[1] Some polymers also have highly advanced mechanical properties, such as shape memory polymers, which can be altered and returned to their original shape by applying a magnetic field or temperature stimulus.

Finally, polymers are closer to biological tissue than inorganic materials. They can often interact better with the human body without the risk of an adverse reaction.

Some current uses for polymers in medicine include vascular stents, clot removal devices, drug delivery devices, clot removal devices, and orthodontic therapy. Polymer optical components may also be used in advanced machines and systems like imaging, diagnostic, and sensors.

The Polymer Injection Molding Process

Plastic components, from consumer products to automotive parts to medical devices, are created using the injection molding process. Though this is a precise and cost-effective fabrication process, it does require expertise with complex systems and tight parameters.

First, the mold for the polymer component is created using computer numerical control (CNC) machining or other methods. This method uses a computer to control the process and ensure accuracy in the finished mold, though other methods may be used.

Creating the mold is one of the most time-intensive and costly parts of the process. Because polymer shrinks as it cools from a liquid state to a solid state, the mold must accommodate these changes without affecting the precision of the finished component.

The material for the mold is another consideration. Different metals have advantages and disadvantages, which must be weighed against the production cycle. Generally, a less expensive metal is a good choice for a shorter production cycle since it won’t hold up to high-volume manufacturing, like 100,000 units. Conversely, a more robust metal may require a higher initial investment that’s cost-prohibitive for a shorter production cycle but ideal for mass production.

Once finalized, the injection molding process can begin. The thermoplastic is pelletized and fed through a hopper into a heated barrel with a reciprocating screw to melt it. The material passes into a gate, where it shoots into the mold.

No matter the type of machine, polymer injection molding involves forcing molten polymers into a mold and clamped, which creates the final component. Each mold produces millions of parts in a lifetime, so they must be robust with low tolerances.

Advantages of Plastic Injection Molding for Medical Devices

Polymer injection molding is ideal for cost-effectively manufacturing precision parts and components for medical devices. Here are some of the advantages:

Compliance with Industry Standards

The medical industry has numerous regulations from governing agencies like the Food and Drug Administration. Any components manufactured for medical devices, including optical components, must comply with requirements for safety and sterility.

Plastics are easier to clean and sterilize than other materials, such as metals. They’re also resistant to contamination and have fewer finishing requirements, making them a safer and more hygienic choice for medical purposes.

Material Compatibility

The injection molding process uses various materials, including plastics, composites, and fibers. For the medical industry specifically, which has specific requirements for safe and sterile materials, polymer injection molding is highly compatible with medical-grade plastics.

Cost Effectiveness

Injection molding can be automated and works well for large-scale manufacturing. A computer can control the entire process, producing precise identical components and lower labor demands. Because of the high volume, each part is a lower price per unit, contributing to cost-effective mass production. It’s also a fast process that reuses the mold repeatedly, further reducing the production cost for medical-grade components.

High Accuracy and Precision

Medical optical components, including precise imaging, require dimensional accuracy to support diagnostics and treatment. If an element isn’t exact, the inaccuracy could harm a patient. No matter the type of machine, polymer injection molding involves forcing molten polymers into a mold and clamped, which creates the final component.

Low Material Waste

All manufacturing processes create waste, but injection molding waste has some reusability. Any scraps produced can be gathered, melted, and reused in other component fabrication. Leading to lower waste in the overall process.

High-Volume Capabilities

Many medical components are designed for single use, while others must be produced in high volumes to account for complex systems or multiple products. In either case, polymer injection molding offers high-volume repeatability. Once one mold is created and perfected, it’s quick and cost-effective to fabricate hundreds or thousands of identical parts from that upfront investment.

Polymer Injection Molding from Apollo Optical Systems

If you have a custom project for medical devices and components, Apollo Optical Systems can help. We offer high-precision polymer injection molding, from design to mass production, to ensure your project meets its cost and performance specifications. Contact us today to discuss your custom optics project!




About Dale Buralli

Dr. Dale Buralli has served as the Chief Scientist for Apollo Optical Systems since 2003. In this role, Dr. Buralli is responsible for the design and optical modeling of various optical systems. These systems include virtual or augmented reality, ophthalmic and other imaging or illumination systems. Additionally, he provides support for optical tooling of lens molds and prototypes, including the development of custom software for both production and metrology. Dr. Buralli got his Ph.D. in optics from the University of Rochester in 1991. Now he is an Adjunct Professor of Optics at the University of Rochester’s Institute of Optics.