Vacuum Forming & 3D Printed Molds

Vacuum forming is traditionally a slower manufacturing process. Typically a mold needs to be machined, which requires programming & setup time, and then the thermoplastic gets formed. With 3D printing, one can print a mold overnight and form the parts the next day.

Vacuum forming can be done both with FDM and SLA. The latter yields much higher quality in terms of surface finish but is more costly to produce, especially when molds are larger in size. In this blog post we highlight two examples, one with an FDM printed mold, and one with an SLA printed mold.

There are a variety of design guidelines one needs to stick to in order to successfully design and make vacuum formed parts such as draft angles and vent holes. A good starting guide can be found from Formech, a leader in industrial vacuum forming machines.

The first example is a standard packaging tray for a device, pulled in thin PETG. In this example, our client actually provided the mold to us and we just pulled the packaging.

The mold

This is the mold printed in standard resin. This is referred to as a female mold. Plastic stretches and gets pulled into the crevices. In order to get crisp edges, vent holes need to be placed along the perimeter of each cavity.
When a part like this is made, you get subsequent thinning of the plastic for each increasing draw depth. This means that the section that gets pulled down the deepest cylindrical area, will also end up being the thinnest part of the plastic.

The part

You can see the surface finish is very smooth due to the SLA mold and the edges are crisp. It’s difficult to tell from this image, but the deep, tubular area is very thin due to the long draw depth.
After forming these parts need to get trimmed. This can be done a variety of ways, ranging from simple cutting with scissors, knives, a electric or pneumatic powered nibbler, laser cutting to a CNC machine.

Finished job

Mold and parts finished in around 2 days time. A pretty mind blowing complement of two technologies which would otherwise have taken weeks to make. Check out the youtube video below to see this part being made in real time!

In our second example, we look at an ESD safe laser handling tray that was needed to facilitate handling and assembly of a product which contains a highly ESD sensitive laser diode.

The first step was to design and prototype the tray itself, making sure the pockets and overall size was correct for the application. This was done easily and quickly using FDM 3D printing. This prototype is not ESD safe, but that didn’t matter at this stage.

Once the design was proven, outsourcing the vacuum forming to more traditional thermoforming companies was considered. The quotes that came back had a total cost of ~$8000 for 50 trays and had lead times that were approximately 10 weeks out. Instead of going this route, we created the mold using the Solidworks mold tools, 3D printed it in a high temperature polymer like Polycarbonate and then started vacuum forming the next day.

These parts were made using special ESD ABS and we manufactured the run of 50 trays. Although the operation time of a smaller benchtop machine is slower than a more industrial one (eg. Formech), the Vaquform performed well and the parts came out fantastic.