Plastic comes in different sizes, types, colors, and with different material characteristics. The wide variety of plastic makes it a crucial material for manufacturers interested in producing both prototypes and end-use parts for use. Thermoforming is a manufacturing process that empowers manufacturers with a versatile solution for processing plastic sheets. 

In this article, TLD Vietnam breaks down the fundamentals of thermoforming, explores some common thermoformed products, and explains a prototypical thermoforming manufacturing process.

What Is Thermoforming? 

Vacuum forming

Vacuum forming is the cheapest and the oldest type of plastic molding. The process is usually widely used for smaller objects and heavy industrial machinery that are used in everyday life. The process is employed at a large scale because of the benefits offered, such as cost-efficiency, the speed of imitation, efficiency in the process, etc. While carrying out this process, a layer of plastic is placed on the mold, and then a force of suction is applied so that the piece gets molded in the desired form. 

This process helps produce a part that is strong, seamless, durable, lightweight, etc. The parts formed using this process are used in thousands of applications to achieve the desired objectives. 

Pressure Forming

Pressure forming is another thermoforming process used to mold products to produce a final product. This process helps develop parts with crisp features and detailed textures. The process and the outcome are more or less similar to vacuum forming vs injection moulding. Though the tooling and production of this process are faster and simpler than injection molding. 

Moreover, the cost of producing plastic products through pressure forming is just a fraction of what is otherwise spent on other processes. You can choose the ideal process based on all your specific needs. The parts formed by this process have sharper and crisper details, much better than the rival molding procedures. 

Twin Sheet Forming

It is a plastic manufacturing method in which two sheets are formed simultaneously in their respective mold and are then pressed together. The procedure employed in this is either pressure forming or vacuum forming. 

While the sheets are being pressed together, a small pin is made to pass through either one of the sheets, and cool air is blown through it. This causes the formation of pressure. The heat along with the pressure causes the two sheets to fuse together and become one. The excess parts are then trimmed off. This leads to the production of a rigid and strong part.

Thermoforming Materials

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.
• Low-Density Polyethylene (LDPE): LDPE is a thermoplastic that is resistant to chemicals and UV rays. This plastic is also flexible and has high tensile strength. Manufacturers can utilize LDPE to manufacture packaging films, DVDs, cable insulation, containers, and chemical-resistant items. 
• High-Density Polyethylene (HDPE): HDPE is similar to LDPE in terms of its base characteristics and is noted as being resistant to chemicals, UV rays, and water. It is a durable thermoplastic that may be used to manufacture packaging film, blown bottles, containers, pipes, and plastic bags. 
• 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.
• Polycarbonate (PC): Polycarbonates are strong, tough materials that can undergo ​​large plastic deformations without cracking or breaking. They’re heat-resistant, flame-retardant, and have good electrical insulator properties. Some grades of PC are also optically transparent and highly transparent to visible light. PCs are used for plastic lenses in eyewear, in medical devices, automotive components, protective gear (lenses, safety helmets), bullet-proof glass, car headlamps, and construction.
• Acrylonitrile-Butadiene-Styrene (ABS): The characteristics of ABS include rigidity, resistance to abrasion, and resistance to low temperatures. Manufacturers can leverage thermoforming and ABS to produce electronic packaging, food containers, and domestic appliances.

Other materials that manufacturers can use include polytetrafluoroethylene (PTFE), polyamide, HIPS, and more. The choice of material depends on the intended thermoforming technique and the project requirements. The application table can help with making the right choice for potential projects. 

The Advantage of Thermoforming

Thermoforming offers several significant benefits when the right process is selected for the intended plastic product. One of the main advantages is the high quality of the manufactured items, as the method allows for precise shaping and smooth surface finishes. It is also cost-effective, making it suitable for both small and large production runs. Another notable benefit is its ability to manufacture large parts with ease, giving designers greater flexibility in shaping complex components. In addition, the flexibility of tooling design provides strong competitive advantages, allowing manufacturers to adapt quickly to different product requirements.

The Disadvantage of Thermoforming

Despite its strengths, thermoforming also has certain limitations. One drawback is that the thickness of the final product can be uneven in some areas, which may create weak points and reduce overall durability. The process also tends to use more plastic material compared to other plastic-forming methods, resulting in higher material consumption. Furthermore, thermoforming is limited to thin-walled designs, restricting its ability to produce parts with thick or highly detailed structural features.

Conclusion