When it comes to the development of plastic optical components, optical performance is only half the equation. Even the best lens design can fail in production if manufacturability is not considered early. This is where Design for Manufacturability (DFM) becomes critical – aligning optical performance with the realities of mass production.
In this article, we explore why DFM matters and how key design aspects influence the success of plastic optics.
1. Understand the Limitations of Injection Molding
Optical injection molding enables the efficient production of complex shapes. But the process brings constraints:
- Shrinkage and warpage during cooling
- Flow lines or weld lines
- Limitations in demolding direction and draft angles
Ignoring these can lead to expensive tool modifications or unfeasible designs.
2. Design with Draft Angles and Parting Lines in Mind
Every molded part must be ejected from the mold – without damaging the part or the optics. That’s why:
- All vertical walls should have proper draft angles (usually 0.5°–1° or more)
- Critical optical surfaces should avoid being placed across parting lines
Deciding where to place those elements early ensures better surface quality and avoids defects.
3. Consider Shrinkage and Dimensional Stability
All plastics shrink to some degree during cooling. Optical components require very tight tolerances:
- Include expected shrinkage in your CAD model
- Choose materials with low and predictable shrinkage (e.g., COC/COP)
- Avoid asymmetric wall thicknesses to reduce warpage
4. Avoid Undercuts and Complex Tool Actions
Complex geometries increase tooling cost and risk. Undercuts may require sliders or collapsing cores.
- Simplify wherever possible
- Use snap fits or mounting features only when necessary
- Align features with tool opening direction
5. Optimize for Flow Behavior
Flow paths and gate locations affect how plastic fills the mold:
- Avoid sharp corners and sudden thickness transitions
- Think about flow orientation and potential weld lines
- Place gates away from critical optical surfaces
Simulation software can help visualize flow patterns before tooling.
💡 Today’s mold flow simulations go even further – many modern tools can now simulate birefringence patterns caused by internal stress or flow behavior, which is especially critical in precision optical components. Incorporating this data early on allows designers to optimize geometry and gate placement to reduce optical distortion.
6. Involve ALL-IN OPTICS Early in Your Design Process
The sooner we are involved in your optical development, the more value we can provide. With years of hands-on experience in optical design and manufacturing, ALL-IN OPTICS supports you in aligning your product vision with production realities.
- We evaluate design feasibility from a manufacturing perspective
- We help identify risks related to tooling, shrinkage, or tolerance issues
- We contribute valuable feedback based on real-world optical production know-how
DFM is not a one-time check – it’s an iterative process that benefits greatly from early collaboration with experienced partners like us.
Conclusion
An optical design that ignores manufacturability might look good on paper, but will struggle in reality. By applying DFM principles early, you ensure:
- High optical quality
- Reliable production
- Lower tooling and per-part costs
Whether you’re designing a microlens, light guide, or optical cover – successful plastic optics start with manufacturable design.
Need support turning your design into a series-ready component? Contact us – we help align optics, design and production every step of the way.
