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

High-quality molds for thermoforming can be created through various manufacturing methods, including 3D printing. In our 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?

What are the benefits of SLA?

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

Printing Complex Patterns
SLA 3D printing can achieve very fine details. This is extremely 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 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 the Mayku Multiplier, we recommend vent holes no larger than 0.4 mm. Larger vent holes can result in noticeable marks on the final printed part or cause the plastic sheet to tear during forming. We also recommend testing the minimum vent hole size of 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 mold surface, with the holes widening to about 2 mm at the back of the mold. This prevents resin from getting trapped.
• Remove any uncured resin from inside all vent holes with a needle or air gun before post-processing and curing the mold.

Print Orientation
When slicing a print, always orient the part to minimize visible support material. 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 consumption.

When making hollow molds, support structures should be added to the interior of 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. 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 filament 3D printing (FDM). 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 worth noting that if the mold's geometry has many curved features, layer lines may be more noticeable. In such cases, you can better hide layer lines by printing thinner layers and modifying the print direction.

Applications of SLA Thermoforming Molds
Thermoforming molds made with SLA 3D printers play a crucial role in various industry applications. 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 suitable for demanding work environments.

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

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