[3D Printing Knowledge] Application Guide for Creating Thermoforming Molds with SLA 3D Printing

High-quality molds for thermoforming can be achieved through various manufacturing methods, including 3D printing. In a previous article, we explored the techniques and practical knowledge of using SLS for creating thermoforming molds! In this article, we will delve into creating thermoforming molds using SLA 3D printing, including best practices, advantages, and more.

What is Resin 3D Printing?

So what are the benefits of SLA?

Smooth Surface Finish
SLA 3D printing can produce parts with smooth surfaces without any post-processing, saving a significant amount of time! A smooth surface is very useful in thermoforming, making it easier to demold the finished product in certain applications, reducing the process and maintaining quality.

In the image below, you can see that the resin 3D printed part (SLA) has no visible layers, while the same part made with filament 3D printing (FDM) has clear layer textures.

Print Complex Patterns
SLA 3D printing can achieve very fine results. This is very useful in thermoforming, especially when creating molds with specific surface patterns, textures, or even text.

Compatible with Various Materials
SLA 3D printing is compatible with dozens of resins, each with specific properties. Some of these resins, such as Formlabs' High Temp Resin, are ideal materials for making thermoforming molds.

Formlabs High Temp Resin (Source: Formlabs)

Designing and Manufacturing Thermoforming Molds
Here are some tips and best practices to pay special attention to when designing and producing thermoforming molds using SLA 3D printing.

Vent Hole Size
Since SLA 3D printing is very precise, you can create vent holes so small they are almost invisible. For Mayku Multiplier, we recommend vent holes no larger than 0.4 mm. Larger vent holes may result in noticeable holes in the final printed part or cause the plastic sheet to tear during the forming process. We also recommend testing the minimum vent hole size for your mold during the prototyping phase.

Thermoforming mold with vent holes

Here are two tips for achieving optimal vent holes:

• Add 0.4 mm tapered vent holes to the surface of the mold, with the holes becoming larger (about 2 mm) at the back of the mold. This prevents resin from getting trapped.
• Clear any uncured resin from all vent holes with a needle or air gun before post-processing and curing the mold.

Print Orientation
When slicing for printing, always orient the part to minimize visible support material on the part. This will make your printed mold look better and save post-processing time.

Hollow Molds
In some cases, making hollow molds can reduce print time and material usage.

When making hollow molds, support structures should be added inside the object to increase its resistance and allow for multiple uses. The internal structure can then be filled with plaster or similar material to make the part solid again, but it is important not to cover the vent holes, and the density of the mold's interior depends on the application and its overall size.

Finally, if your mold will be used with a Mayku Multiplier desktop pressure former, we recommend using a shell of at least 5 mm on hollowed objects.

Layer Height
Layer lines in SLA 3D printing are less noticeable than in FDM 3D printing. If your mold requires a smooth surface, use a layer height of 0.05 mm on the final mold to minimize the visibility of layer lines.

It's also important to note that if the mold's geometry has many curved features, the layers may be more noticeable. In this case, you can better hide layer lines by printing thinner layers and modifying the print orientation.

Applications of SLA Thermoforming Molds
Thermoforming molds made with SLA 3D printers play a crucial role in applications across various industries. These include:

• Industrial Design: High levels of detail and complex geometries are critical for industrial designers, and resin 3D printing meets their needs by creating enclosures for products or other parts or tools that are suitable for demanding work environments.

• Chocolate: Clean surface textures and small details are essential for chocolate makers. Resin 3D printing is a nearly perfect technology for creating unique and intricate designs.

• Packaging: When prototyping packaging, high levels of detail and mold dimension tolerances are key, and SLA 3D printing technology can achieve precisely that.