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.
Twin Sheet Forming: This process involves the forming of two layers and combining them to form one item. The plastic sheets are heated simultaneously, formed, and joined together to produce an item. The twin sheet forming process is best used to manufacture hollowed items or items with double walls.
Billow Forming: The billow forming process is a free-form thermoforming technique that does not rely on molds to shape the heated plastic. Here, the forming machine uses air jets to blast the plastic into a bubble until the final design is formed.