Vacuum forming is a method that uses vacuum and compressed air to shape plastic parts from rolls or sheets. In this process, also known as vacuum thermoforming, the vacuum pump plays a crucial role. In this article, we explain the key aspects of the vacuum forming process.
Sarah Guaglianone
Updated on June 3, 2026
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Plastic vacuum forming is a process in which vacuum and, if necessary, compressed air are used to produce formed thermoformed parts from plastic sheets or rolls. It is one of the oldest thermoforming processes and is still used in many industries today.
While negative pressure is generated in vacuum forming, pneumatic forming additionally works with compressed air to apply greater force during the forming process. This article focuses on classic vacuum forming.
In plastic vacuum forming, the heated semi-finished product (sheet or roll) is drawn over the tool using negative pressure. A vacuum pump generates a vacuum of approximately 1 bar, so that the air between the material and tool surface is extracted. As a result, the material conforms closely to the tool contours and takes on the desired shape.
A frequently occurring problem in plastic vacuum forming is that the negative pressure decreases when the heated material is applied to the tool. However, the greatest forming pressure is needed precisely in this phase of the forming process.
This can be optimized through a two-stage vacuum system, which requires a vacuum pump with high volume capacity. Here, a second vacuum is generated before the material cools.
The advantages: In this way, the material is better distributed into the corners of the tool, and the contours of the molded part become sharper. Radii can also be reproduced smaller in this way.
Although plastic vacuum forming has its disadvantages compared to pressure forming in terms of economical production of large series and complex geometries, vacuum thermoforming is sufficient especially for uncomplicated parts and small volumes. Due to the low forming pressure, vacuum forming is therefore particularly suitable for relatively simple parts, such as plastic inlays for packaging or plastic trays for food.
Plastic vacuum forming proves to be extremely advantageous for the production of plastic parts, especially for uncomplicated parts and small volumes.
| Advantages of Plastic Vacuum Forming | Disadvantages of Plastic Vacuum Forming |
|---|---|
| Suitable for simple parts | Lower form sharpness compared to pressure forming |
| Low tooling costs | Higher risk of blemishes compared to pressure forming |
| Lower energy consumption than pressure forming | Lower temperature resistance than pressure forming |
| Cost-effective for small production runs | Longer cycle times than pressure forming |
Nevertheless, it is important to always keep the overall calculation in view. This means that when deciding on plastic vacuum forming, both tooling and molded part costs should be carefully considered.
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Plastic vacuum forming offers an economical and efficient solution for the production of plastic parts. It is particularly well suited for uncomplicated parts, small volumes and applications such as packaging inlays or food trays. The advantages, including cost-effective tools, energy efficiency and versatile applicability, make the vacuum forming process a popular choice in various industrial sectors.
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The vacuum forming process is particularly suitable for small to medium series where low tooling costs and fast implementation are required.