PLASTIC THERMOFORMING + VACUUM (vac) FORMING

This page talks about the world of plastic thermoforming - think the plastic piece on our Club packaging.

Plastic Thermoforming and Vaccum (vac) forming

These words are used interchangeably in the packaging industry.

Thermoforming is a plastic manufacturing process that involves heating a plastic sheet and forming it using a mold to specific shapes. The shaped plastic then gets cooled down and trimmed to result in the finished part. The process is executed using a thermoforming machine to heat and stretch the pliable thermoplastic sheet over the mold. Modern thermoforming machines are generally equipped to handle the trimming and cutting process, while for more conventional machines, trimming and cooling may be done externally.

The process

Thermoforming Processes

Thermoforming is an all-inclusive manufacturing process that embraces all the different ways manufacturers may choose to form heated sheets of plastic. A manufacturer which chooses the vacuum forming process or pressure forming process is taking advantage of thermoforming.

Although a variety of processes exist, the most popular thermoforming techniques are the following:

Vacuum Forming: This thermoforming process makes use of a vacuum to shape the sheet. First, the plastic sheet is heated to ensure it is flexible. The vacuum forming machine then pulls the air out, forcing the sheet against a mold. The vacuum process is known for its cost-effectiveness and the speed of the manufacturing process.
Pressure Forming: The pressure forming process similarly involves the heating of the plastic sheet and utilizing a vacuum to pull air away to force the sheet against a mold. But there’s an extra step. A pressing tool applies pressure once the air is removed to ensure the shaped plastic better maintains its final shape. Pressure forming is used when higher levels of details are required from the thermoforming process.
Mechanical Forming: This process involves the use of a direct mechanical force to shape the preheated plastic sheet. A core plug forces the pliable sheet to fill a space between the plug and the mold, and this imprints the surface patterns onto the plastic sheet. Mechanical thermoforming is used when precision and high levels of detail are required.
Drape Forming: In drape forming, the heated plastic sheet is draped onto a mandrel designed with specific patterns. The mandrel’s pattern is pressed onto the plastic sheet to form the finished part. The drape forming process is one of the most-affordable thermoforming techniques because limited tooling is required. As the thickness of the material can be maintained, the process doesn’t result in weaknesses in the parts.
Matched Mold Forming: This thermoforming process is applied when manufacturing items that require higher levels of accuracy. The matched mold forming process involves the use of a male and female mold to shape the heated plastic sheet. The forming machine applies force to bring the molds together onto the plastic sheet. The sheet then takes the pattern or shape designed into the two molds.

Thermoforming Materialsls

Plastic Options

Thermoforming is applied to produce food packages, aircraft components, toys, pallets, and other plastic items. Hence, it is necessary for manufacturers to consider a diverse range of plastic materials prior to a production cycle. The more commonly used materials for thermoforming include:

Polypropylene (PP): PP is the most popular plastic material for thermoforming in terms of value and volume. It is commonly used in manufacturing packages, ventilators, toys, and other plastic items. Polypropylene is used because of its innate properties such as excellent resistance to chemicals, fatigue, and heat. Polypropylene is also an affordable material and can be used with the diverse thermoforming processes highlighted here.
Polystyrene (PS): This aromatic hydrocarbon polymer provides manufacturers with a clear, hard, and brittle plastic to work with. Polystyrene is widely used as a thermoforming packing material as it offers qualities such as resistance to water and air. Manufacturers use polystyrene to manufacture food packaging, jewel cases, CD cases, and domestic items.
Polyethylene Terephthalate (PET): PET provides very good alcohol and essential oil barrier properties, good chemical resistance, and a high degree of impact resistance and tensile strength. It is commonly used for carbonated beverages, water bottles, and many food products.
Polyvinyl Chloride (PVC): PVC is another popular plastic used in manufacturing pipes, window frames, automotive interiors, domestic items, packages, and footwear. PVC can be developed to be either rigid or flexible depending on the manufacturer’s requirements. This thermoplastic is also dense, durable, and resistant to water. It is important to note that PVC isn’t completely chemical resistant and may react to chlorine.