Plastic thermoforming: basic knowledge for beginners

Introduction

Thermoforming is a widely used process for manufacturing plastic parts and packaging. It is a cost-effective way to form a variety of products from thermoplastic materials, widely used in industries such as packaging, automotive, and medical technology. Thermoforming can be divided into two main categories: film thermoforming and sheet thermoforming. These methods differ in the materials used and their areas of application. In this blog post, we will explain the basics of thermoforming, highlight the differences between film and sheet thermoforming, and describe typical applications.

What is Thermoforming?

Thermoforming is a process in which thermoplastic materials are heated until flexible, then shaped in a mold. Once cooled, the plastic retains the desired shape. The process is commonly used to produce packaging, housings, and other thin-walled plastic products.

The Thermoforming Process: Step by Step

1. Material Preparation: The process starts with a plastic sheet or film, typically made of a thermoplastic material. This is heated until it becomes soft and formable.
2. Heating: The plastic sheet or film is heated to a temperature where it is flexible enough to be shaped without melting.
3. Forming: The heated plastic is either pulled into the mold using vacuum or pressure:
   • Vacuum Thermoforming: The plastic is pulled into the mold by creating a vacuum.
   • Pressure Thermoforming: Additional pressure is applied to press the plastic into the mold.
4. Cooling: The formed part is cooled to retain its final shape.
5. Trimming: The finished part is cut out of the plastic sheet or film.

Difference between Film Thermoforming and Sheet Thermoforming

Thermoforming can be broadly divided into two main processes: film thermoforming and sheet thermoforming. These methods primarily differ in the thickness of the starting material and the type of products they produce.

Film Thermoforming

• Material Thickness: Uses thin plastic films with a thickness of less than 1.5 mm.
• Applications: Typically used for packaging, such as food containers, blister packs, and disposable items.
• Advantage: Lower material costs, ideal for producing lightweight packaging and products in large volumes.
• Disadvantage: Limited stability and strength of the final products.

Sheet Thermoforming

• Material Thickness: Processes thicker plastic sheets with a thickness of more than 1.5 mm.
• Applications: Used in the automotive industry (e.g., interior trims), large enclosures, and durable consumer goods.
• Advantage: Stronger and more stable end products, ideal for technical applications.
• Disadvantage: Higher material and tooling costs.

Typical Materials for Thermoforming

Thermoforming Comparison: Film vs. Sheet Thermoforming

Conclusion

Thermoforming, whether film or sheet thermoforming, offers an efficient and flexible solution for producing plastic parts and packaging. The choice between film and sheet thermoforming depends on the requirements of the final product – film thermoforming is ideal for lightweight, cost-effective packaging, while sheet thermoforming produces more robust and durable parts. Both processes have their own advantages and disadvantages, but they offer a cost-effective alternative to other manufacturing methods such as injection molding.