What Is Thermoforming

Every day, millions of people interact with and use numerous items made through a thermoforming process. What is thermoforming? Merriam-Webster defines thermoforming as a product manufacturing process that gives a final shape to a product (typically plastic) with the aid of heat, a mold, and usually pressure. More specifically, thermoforming starts with heating a plastic sheet to a temperature that makes it flexible to stretch and shape into a precise shape in a mold. The cooled item is cut or trimmed to produce a functional product. 

Packaging products created with the thermoforming process include several different thermoforming processes. Each process has unique advantages and disadvantages, depending on the type of material used. While each process differs, many of the same components are required. For example, some combination of heat, vacuum, or pressure is almost always needed to manipulate the plastic into a mold. 

Depending on the project, product, and process, several types of plastic and materials are used in the thermoforming process. Each project's requirements and characteristics are unique, which help determine the type of plastic selected, such as polystyrene, PET, polypropylene, polycarbonate, etc. Some plastic products manufactured with thermoforming are considered short-term or one-time use, such as items used in medical and pharmaceuticals, food packaging, and many more. This type of packaging product is referred to as a thin-walled package. More durable plastic products like that seen in an automobile, an airplane, or numerous other manufactured durable items require thicker walls that will stand the test of time of repeated use for years.

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Thin-walled thermoforming is a high-quality, cost-effective option for both small and large quantities. When embarking on a new thermoforming project, it's always a good idea to consider the following thermoforming process options when deciding on the forming process.

Vacuum Forming- Plastic sheet is heated, and a vacuum is used to remove the air out, thus shaping the plastic over the form.

• Low-cost and fast manufacturing process.
• Low to large-volume productions.
• If precision and accuracy are not required.

Pressure Forming- The process is similar to a vacuum with the addition of a press tool to create a more detailed finish.

• Low-cost process.
• Low to large-volume productions.
• Used when long-lasting items are uniform and durable.

Mechanical Forming- Using a mechanical force, the heated sheet fills the area between the plug and mold, forming a detailed part.

• Low-cost manufacturing process.
• Only for Medium to large-volume production.
• For use when quality and precision are required.

Drape Forming- A less expensive thermoforming process when the pattern is pressed onto the heated sheet. 

• Low Cost and fast process.
• Only for Medium to large-volume production.
• Large and thick section materials with minimal curves.

Matched Mold Forming- Used when accuracy is important involving a male and female mold.

• Higher manufacturing process due to the tooling required.
• Medium to large-volume production.
• Most likely for durable parts, cars and fixtures.

Twin Sheet Forming- Joining two plastic sheets together to create one item.

• Affordable manufacturing process.
• Medium to large-volume production.
• Seen in packaging items such as hollowed and double-walled items.

Thin Wall Thermoforming Materials

• Polypropylene (PP)
• Polystyrene (PS)
• Polyethylene Terephthalate (PET): 
• Low-Density Polyethylene (LDPE
• High-Density Polyethylene (HDPE): 
• Polyvinyl Chloride (PVC
• Polycarbonate (PC): 
• Cellulose Acetate
• Polymethyl methacrylate (PMMA): 
• Acrylonitrile-Butadiene-Styrene (ABS): 
• Polytetrafluoroethylene (PTFE),
• polyamide, 
• HIPS and more

Another significant thermoforming consideration includes the project gauge requirements; heavy versus thin. The thickness of the plastic fed into the machine, the process applied, and the desired outcome thickness all determine the quality of the final product. The gauge is the part wall thickness at the end of the process. Knowing how thick the walls must be to create a successful part can help narrow down the process choices. Below is the rule of thumb guides when choosing the correct gauge; heavy or thin.

Part Thickness

• .060–.375″ 1.5–9.5 mm Heavy Gauge
• < .125" < 3 mm Thin Gauge

Thermoformed packaging is a deep and expansive science all of its own. New and exciting breakthroughs in process and material sciences are happening every day. Taking the time and involving experts in the field is critical to designing and producing a well-made, cost-effective, and appealing package. If you have any questions or would like to discuss your project confidentially, feel free to contact the packaging experts at Tek Pak.