Thermoforming is a manufacturing process used to shape thin sheets of thermoplastics common in the packaging, medical, industrial design and automotive industries. A wide variety of everyday items are created using thermoforming, from takeout containers to RC cars.
Vacuum forming is a type of thermoforming that uses thin sheets of special plastic and a vacuum. Heat makes the plastic pliable, and then vacuum is used to pull the heated plastic sheet around the mold. Typically molds are made from wood, cast aluminum, machined aluminum, or composites. Using these materials can be costly and time consuming.
Many companies are turning to 3D printed molds for this application. 3D printing the molds is allowing thermoformers to do iterative sampling and even custom forming for their customers at a low cost and high speed. Parts created with a printed mold can be used at any stage of product development, including production, concept development, and prototyping phases.
3D systems has worked on this application extensively, focusing on the use of four different 3D printing technologies: plastic jet printing (PJP), color jet printing (CJP), multi-jet printing (MJP), and Sterolithography (SLA). Let’s take a closer look at how to vacuum form by reviewing the full process from start to finish.
The Vacuum Forming Process:
- Mounting the printed molds: Place the 3D printed molds on the vacuum table and lower the table and molds into an open chamber in the machine.
- Loading the material: Clamp a sheet of thermoplastic in the vacuum forming machine. Heat the plastic sheet until it becomes malleable for forming
- Vacuuming thermoplastics: raise the 3D printed mold up into the plastic sheet causing the sheet to drape over the mold. Switch on the vacuum to evacuate the air. This draws the plastic sheet around the mold.
- Remove the Mold: Lastly release the plastic from the molds and allow to cool.
Aside from cost savings, 3D printing your molds also offer other advantages. Plastic Jet printing and Color Jet printing 3d printed parts are naturally porous. These parts allow air to flow through them. During the thermoforming process, this porosity allows the plastic sheet to form to the mold much easier. Surface finish is smooth when using the Multi-Jet or Sterolithography printing methods. This is key because the surface finish transfers from the mold to the vacuum formed part. 3D printing your molds can accurately and cheaply make geometries that are expensive to make with traditional methods. Lastly, the ability to keep your mold inventory digital, frees companies from having to hold physical inventory.
Personally, I think that every company that is thermoforming should have at least one type of 3D printer in house to create molds for design testing, prototyping, form and fit, or production. 3D printing molds at any place in the design cycle is the best way to keep up with the competitive thermoforming industry.