What is thermoforming? How do you thermoform PETG?

Thermoforming is the process of converting flat plastic sheets into 3D shapes by using heat and vacuum. Eastman Spectar™ copolyester (PETG) is one of the best plastic materials for thermoforming! Sheets made from Spectar do not need to be predried before forming. This gives your customers an efficiency bonus compared to polycarbonate. Sheets made from Spectar reach their forming temperature quickly—faster than acrylic or polycarbonate—saving your customers time and energy and yielding parts with crisp, clear details.

Basic steps of the thermoforming process:

  1. Plastic sheet is clamped or fastened and is then suspended in a heated oven to allow softening and sagging.

  2. Heated sheet is then transported to a molding area and draped over a cool mold.

  3. Vacuum is drawn through the mold, pulling the hot sheet against the mold.

  4. Hot sheet takes the shape of the mold.

  5. Plastic cools and is transported to a trimming station where the formed part is trimmed out of the full-size piece.

Click here to see thermoforming in action!

Spectar Thermoform Video

 

Tips for thermoforming Eastman Spectar™ copolyester:

  • Typical mold constructions are aluminum, MDF board, and plaster.
  • Use a minimum draft angle of 5° in male molds for easy part release.
  • Use lower oven temperatures than necessary for acrylic or polycarbonate. A good range for oven temperature is 400° to 480°F.
  • Heat the sheet to 275° to 310°F. Use higher temperatures for deep-drawn parts and high detail. Use lower temperatures for large parts and shallow draws. The optimum is 300°F when using a top-sided heat oven and measuring the top part of the sheet.
  • Use a vacuum of 508 mm (20 in.) Hg or greater.
  • For highly detailed molds, a light dusting with talcum powder helps the part release more easily and will extend the life of the mold as well.
  • Always allow generous radii on internal corners—2x or more the initial sheet thickness.

Sheet made from Spectar is excellent for reproducing mold details. It gives fabricators the ability to create highly intricate shapes compared to acrylic and other materials.

Spectar Thermoform

You can view videos on many of the processes mentioned in the preceding text at our Spectar video gallery.

For additional tips, download our Fabrication Guide.