Answers to the most common thermoforming questions
Q. How does thermoforming work?
A. To thermoform a plastic product:
- A sheet of thermoplastic material is heated in an oven.
- The heated sheet is set on a mold.
- Air either pulls the sheet against the mold, presses the sheet into the mold, or both, creating a 3D object.
- When the formed plastic cools and hardens, it’s removed from the mold and trimmed.
- Products can be painted, hot stamped, die cut or otherwise enhanced—if coloring and detailing weren’t already achieved during the forming process (e.g., through tooling or colored plastic).
Q. What’s the difference between thermoforming and plastic injection molding?
A. Thermoforming—particularly pressure forming—can produce products with the same quality and detail as plastic injection molding. In fact, it’s difficult to distinguish a part that’s been pressure formed from one that’s been injection molded.
However, pressure forming is often preferred to injection molding because:
- Tooling is less expensive. Tooling for a pressure-formed part can be up to 90% less expensive than tooling for an injection-molded part. Molds for pressure forming are one-sided, unlike an injection mold that has a cavity and core.
- Getting to market is quicker. Because their tooling is simpler to build, pressure-formed parts can get into production—and to market—faster than injection-molded parts.
- Redesigns and updates are easier. Unlike injection molding, when a pressure-formed part needs to be redesigned, existing tooling often can be modified quickly and affordably. Replaceable inserts can add new styling features, logos, openings or other variations.
Q. Which is better: vacuum forming or pressure forming?
A. It depends on the benefits you need.
Vacuum forming can cost less for small production runs, or for products requiring less detail and complexity. It’s preferred for producing items quickly, and for building large items that need to be lightweight (with thin walls).
Pressure forming is the best option when aesthetics are important. Pressure-formed plastic rivals the cosmetic appearance of injection molding, with detailed textures and crisp features. It’s preferred for items that require sharp corners or formed-in logos, indicia or other styling.
Q. How do I know which plastic sheet material is best?
A. Each plastic sheet material has physical characteristics that make it suitable for certain applications. Joslyn Manufacturing has worked with nearly every type of thermoform plastic, so our engineering team can help you find the best base material for your project. When selecting a sheet material, we consider thickness, finish, durability, rigidity and other factors. See our materials page for more about the resins we recommend most often.
Q. Isn’t thermoforming only for thin-gauge products, like disposable cartons?
A. No. Thermoforming is often used to create food trays and packaging. But it’s also effective for custom forming other, long-lasting plastic products for a wide range of industries. You can find thermoformed plastic parts in cars and trucks, appliances, lawn and garden equipment, toys, instrument panels, office products and much more.
Q. How thick can the walls of plastic formed products be?
A. Thermoformed plastic products can be made from plastic sheets as thin as 0.005" or as thick as 0.600". Most standard-sized parts use plastic stock with thickness between 0.062" and 0.375".