Louvers for thermoformed parts

Louvers add value to thermoformed parts. They support ventilation or cooling without compromising style or part strength. Understanding how to best design louvers for function, design, and manufacturing ensures the success of your final thermoplastic part.

This discussion equips you with design guidelines and important considerations for including louvers on close-tolerance parts with high levels of finish.

What are louvers?

Louvers are design features that provide ventilation and air flow, while keeping out water, direct sunlight, or foreign objects. They usually present as parallel angled slats.

Allowing more fresh air movement is the key distinction between louvers and vents, which simply allow heat dissipation. This difference impacts cooling rates. Louvers are important for products like electrical or medical equipment.

Louvers can offer some additional rigidity to an OEM part design, a function also provided by ribs. They are simple to add to the design. The openings are made by CNC machining after forming.

Design guidelines for louvers

When designing louvers, key factors include spacing and orientation, radii and transitions, and draft.

• Spacing and orientation enable louvers to maximize airflow while maintaining their rigidity. The depth, angle, and thickness of the louvers determines the amount of spacing to use.
• Radii and transitions help prevent stress concentrations and ensure proper material distribution. Avoid tight radii or sharp transitions which may cause webbing or sink marks.
• Draft prevents sticking or tearing of the material, but undercuts typically require mold actions such as lifters or sliders to relieve undercuts and promote part release.

Additional considerations for louvers

When designing louvers, review the airflow direction to avoid the buildup of heat inside the enclosure. This is especially important for heat-generating devices such as power supplies.

In addition, consider the location of the louvers. For example, a child-safe medical device may need louvers that are hidden from view or small enough to keep out a child’s fingers.

There are some specific instances, like when placed on the side wall of the part, when louvers may require recessed design features known as undercuts. These require articulated tooling elements to allow the thermoformed parts to be removed from the mold. The added value of undercuts far outweighs any cost differential.

Finally, make sure that you’ve addressed all application-specific requirements. For example, if you’re designing louvers for an electric-powered irrigation system, it’s important to keep out water. The angle of the louver design can affect ingress protection.

Conclusion

After better understanding these features and their limitations, where should you start? Ideally, it’s best to partner with an experienced thermoformer to begin early Design-For-Manufacturability (DFM) reviews to optimize your concept. You’ll gain the expertise you need to overcome challenges and turn your ideas into reality.

Download the Thermoforming Design Guide for additional information about louvers, as well as other critical design features.