What is Plastic Vacuum Forming? A Brief Explanation of Vacuum Thermoforming
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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Contents
Plastic vacuum forming - The essentials in brief
Plastic vacuum forming is a thermoforming process in which heated plastic sheets are drawn into a mold using negative pressure to produce components.
Vacuum forming is particularly suitable for small to medium series, as the tools are inexpensive, energy consumption is low and production times are comparatively short.
Typical applications are found in packaging, automotive and medical technology, for example for trays, inlays or simple housing parts.
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.
Difference to other thermoforming processes
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.
How are the molds for vacuum forming produced?
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.
Process in vacuum forming
Heating the semi-finished product to forming temperature.
Placing the material on the forming tool.
Extracting the air through the vacuum pump → The negative pressure presses the material into the tool contours.
Cooling of the plastic → Removal of the formed part.
Simplified representation of the plastic vacuum forming process
Typical problem in vacuum forming
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.
Solution: Two-stage vacuum system
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.
Where does vacuum forming make sense?
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.
Possibilities and limitations in plastic vacuum forming
Plastic vacuum forming proves to be extremely advantageous for the production of plastic parts, especially for uncomplicated parts and small volumes.
Economic advantages of vacuum forming
Affordable tooling costs, due to the simpler construction compared to pressure forming tools
Lower energy costs in vacuum thermoforming than in pressure forming
Limitations of vacuum forming
Less economical for large series
Not suitable for complex parts
Vacuum forming advantages and disadvantages overview
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.
ℹ️ In our formary x Illig webinar on "What is the right process for my thermoformed product?" you will learn in detail which methodology is best suited for your project.
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Plastic vacuum forming - A conclusion
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. Do you have questions or want to have your thermoformed product manufactured using the vacuum forming process? Then contact us or submit a request via the configurator.
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Frequently asked questions about plastic vacuum forming
Vacuum forming is less suitable for very complex geometries, large series and high-temperature-resistant parts.
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