Polymer injection molding is an ideal choice for producing plastic components for complex optical systems and devices. These machines inject polymer materials into closed molds with high pressure and speed, allowing them to produce high volumes of identical components tailored to the project’s specifications.

While there are alternatives to inject molding, such as thermoforming, blow molding, extrusion, machining, and 3D printing, their use cases vary. To date, few alternative processes offer the quality and efficiency of injection molding.

What Is Injection Molding?

Injection molding is a manufacturing process that produces identical parts in high volumes. Injection molding is the top choice for mass-production projects that involve creating the same part thousands – or even millions – of times.

The key advantage of injection molding is that it can be used to scale production quickly. After the upfront costs for the supplies and molding process are covered, the price per unit is extremely low. It also drops significantly as the volume increases, making projects infinitely scalable.

There are other advantages, including:

Strength and Precision

Optical components must be precise to achieve the design requirements and specifications, especially with a high-volume project. With other methods, achieving perfectly identical units is challenging, let alone creating precision parts in high volume.

Injection molding offers a solution to create precision parts repeatedly. Cutting-edge presses can hold tolerances to +/- .001 inches in materials that are known for high shrink rates. Components can be further enhanced with fillers, such as glass and carbon fiber, which increase strength and durability, or additives for UV resistance.


Injection molding allows for more complex geometry and shapes, allowing designers and engineers to create more and more advanced components. Polymer’s high-injection capabilities facilitate uniform units with thin walls and lightweight, which are more versatile than die-cast metal.

Modern polymer injection molding presses can produce many parts with high and low variances for shot capacity and tonnage. These complex shapes are also achievable at a much lower cost, especially for projects that need to be mass-produced on a large scale.

Material Versatility

From polypropylene to polymethyl methacrylate to acrylonitrile butadiene styrene, injection molding offers versatility with material types for optical parts and components. Injection molding also supports multiple polymer materials joined in a unified body, creating more opportunities for polymer projects.

In addition, injection molding can support elastomer materials, such as high-consistency rubber. With these capabilities, designers and engineers can find the right materials for their operating requirements.


As mentioned, injection molding is infinitely scalable. After upfront costs and proof of concept with a successful prototype, optical units can be produced at a low cost per unit for high-volume production in the millions.

Conversely, high-volume production is the most cost-effective use of injection molding. For projects where only one or a few units are needed, the cost may outweigh the benefits, but it depends entirely on the project’s specifications.

Quality Control

Injection molding is repeatable with high precision. It can produce high volumes at a low cost and ensures consistency and reliability across each unit. It’s important to have an optics manufacturer with an in-depth knowledge of the parts, engineering, and material science to navigate the variables for the project, such as the temperature requirements and best materials.

Using knowledge and technology, manufacturers can design injection molds to optimize the design process with fewer compromises to the project’s parameters and specifications.

Expedited Production

After the initial process is perfected, optical components can be produced at high volume in a tight timeframe. Optical designers and engineers can design for mass production before the prototyping process even begins, reducing the expense of tooling changes.

In addition, manufacturers with robust on-site capabilities and a diverse in-house team, such as Apollo Optical Systems, can ensure shortened production timelines and cost-effectiveness for complex projects.

Material Combinations

One of the optical engineering challenges is choosing the right materials for complex optical systems. Different materials have different advantages and disadvantages, but not all optical manufacturing processes allow combined materials.

Injection molding allows designers and engineers to choose the best materials for a project and combine them to get the best performance, reduce the per-unit cost, or increase the strength of the finished component. Some of the materials that can be combined include elastomers, thermoplastics, threaded inserts, and metals.

Additives and Finishes

Injection molding offers versatility in the manufacturing process to include a range of colors, finishes, and additives to improve the durability, performance, or aesthetics of the finished product, all without additional costs. These finishes are included in the initial manufacturing process, eliminating the need for a secondary process that increases the costs and production time.

For example, you may want finishes like colors or light diffusion for the finished product. Additives like UV protection, lubrication, anti-static coating, flame retardants, or weather resistance may enhance the performance of optical systems designed for harsh environments.


In comparison to traditional manufacturing processes, injection molding has less waste. Because it utilizes a higher percentage of the raw material, there’s not a lot of excess thermoplastics or other materials that end up in landfills.

Injection molding requires molten materials that are injected into the mold, then cured to harden. Thermoplastic materials can be melted, cooled, solidified, and melted again without burning, allowing any excess to be recycled over and over. While some plastic can degrade with repeat molding, there’s much less waste overall.

The process itself can be energy efficient as well. Some injection molding machines don’t require the use of fossil fuels like oil in the production or disposal process, making the entire cycle more sustainable.

Is Injection Molding Right for My Optics Project?

Though Injection molding is a versatile process and a go-to for critical applications in industry, automotive, medical, and aerospace use, it’s not ideal for every type of optics project.

Generally, injection molding is a solution for projects that:

  • Require large volume production
  • Have complex components
  • Require high precision, tight tolerances, or reliable unit consistency
  • Need combination materials or additional surface finishes

It’s also important to consider the cost per unit and whether injection molding will be the most cost-effective option. The initial investment can be considerable, but that pays off in mass production.

Precision Polymer Injection Molding at Apollo Optical Systems

Injection molding is an important technology for mass-producing optical components on a large scale and for fine-tuning prototypes. If injection molding is ideal for your project, Apollo Optical Systems offers a consistent, high-quality molding process. We work closely with our customers to ensure success with a finished optical design. Contact us today to discuss your 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.