Vacuum technology
Vacuum Technology – Principles, Applications and Equipment
Vacuum technology refers to the targeted use of negative pressure – that is, air pressure below atmospheric ambient pressure – to control, support or optimise technical processes.
What has been standard practice in industry for decades has long since found its way into skilled trades and ambitious DIY applications: whether laminating fibre-reinforced composites, bonding wood, degassing resins, or storing sensitive materials in a moisture-free environment – vacuum technology is versatile, precise and efficient.
For beginners and experienced users alike: those who understand the fundamental principles of vacuum technology and use the right equipment achieve significantly better results – with less waste, more consistent quality, and reproducible processes.
Fundamentals of Vacuum Technology
Before getting started with practical applications, it is worth understanding the basic concepts and relationships in vacuum technology. This not only makes it easier to select the right equipment, but also helps to identify and resolve process errors at an early stage.
What Is a Vacuum?
A vacuum is defined as a space in which the gas pressure is significantly below the atmospheric ambient pressure. Normal air pressure at sea level is approximately 1,013 mbar (= 1 bar). A technical vacuum typically falls in the range of 1 to 300 mbar – a fraction of ambient pressure. An absolute vacuum (0 mbar) is not achievable in practice, but is also not required for most craft or industrial applications.
For vacuum infusion or vacuum laminating, pressures between 20 and 100 mbar are generally sufficient – values that are easily achievable with a good vacuum pump.
Key Terms at a Glance
| Term | Definition |
|---|---|
| Absolute pressure | Total pressure measured from absolute zero (0 mbar) |
| Gauge pressure / negative pressure | Pressure difference relative to ambient pressure (e.g. −900 mbar) |
| Vacuum level | Measure of the quality of the vacuum produced |
| Leak rate | Volume of air entering the system per unit of time |
| Evacuation | Process of removing air from a closed system |
| Pumping speed | Volume that a pump can evacuate per unit of time (l/min or m³/h) |
Vacuum System Overview
A functional vacuum system consists of several coordinated components. Each fulfils a specific function – and each is critical to the overall performance of the system:
1. Vacuum pump
The heart of every vacuum system. It generates negative pressure by extracting air (and
other gases) from the enclosed area.
2. Vacuum vessel / vacuum chamber
A pressure-resistant, airtight container in which the material to be treated is placed –
for example, for degassing resins or casting compounds.
3. Vacuum film & sealant tape
In vacuum infusion and vacuum laminating, the laminate is covered with an airtight vacuum
film and sealed against the mould using sealant tape (tacky tape). The film must be
flexible, tear-resistant, and chemically resistant.
4. Hoses, connectors & valves
Connect the individual components of the system. Particular attention must be paid to
tight connections and suitable materials (e.g. PVC or polyurethane), as even the smallest
leaks can significantly impair the vacuum.
5. Vacuum gauge / manometer
For monitoring the pressure within the system.
6. Resin trap (optional but recommended)
Protects the vacuum pump from incoming resin or solvents. In vacuum infusion, a resin trap
between the laminate and the pump is essential to prevent damage to the pump.
Symbols in Vacuum Technology
In technical drawings, circuit diagrams, and process descriptions, standardised symbols are used for vacuum technology components.
The most important symbols at a glance:
| Symbol (Description) | Component |
|---|---|
| Circle with inward-pointing arrow | Vacuum pump (general) |
| Rectangle with hatching | Vacuum chamber / vessel |
| Triangle (tip pointing towards line) | Valve (general) |
| Circle with pointer | Manometer / vacuum gauge |
| Dashed line | Vacuum line |
| Double frame | Resin trap / separator |
Note: In practice – particularly in skilled trades and DIY applications – these symbols are primarily relevant in system diagrams and assembly instructions for vacuum infusion setups. A basic understanding makes it considerably easier to read processing instructions.
Fields of Application for Vacuum Technology
Vacuum technology is not a niche topic – it is found across a wide range of craft and industrial processes. The most important application areas at a glance:
Vacuum Infusion (Resin Infusion)
In vacuum infusion, dry fibre material (e.g. glass fibre or carbon fibre fabric) is placed in a mould, covered with a vacuum film, and evacuated. The resulting negative pressure draws liquid resin evenly through the laminate.
Vacuum Laminating / Vacuum Bagging
In the vacuum bagging process, a laminate already impregnated with resin is compacted under a vacuum film. The negative pressure presses the layers together evenly, removes trapped air and excess resin, and ensures a dense, defect-free structure.
Vacuum Pressing (Wood & Veneers)
In woodworking and furniture manufacturing, vacuum presses are used to bond veneers, films or decorative surfaces flatly and without bubbles onto substrate panels. The uniform pressure distribution across the entire surface is virtually unachievable with mechanical presses – vacuum makes it possible.
Desiccators – Drying & Storage
Desiccators are airtight, sealable containers that, in combination with a desiccant or a vacuum pump, are used for moisture-free storage of sensitive materials. In the workshop, they are suitable for storing resin hardeners, hygroscopic powders, or electronic components.
Equipment for Vacuum Technology
A well-equipped vacuum system requires coordinated components. R&G offers a comprehensive range of vacuum accessories for skilled trades, industry, and demanding DIY applications:
Vacuum Pumps
From compact diaphragm pumps for entry-level use to high-performance rotary vane pumps for professional continuous operation. Pay attention to the pumping speed (l/min), the achievable ultimate pressure (mbar), and whether the pump is oil-free – oil-free pumps require less maintenance and are sufficient for many applications.
Vacuum Films
Highly flexible, temperature-resistant films for vacuum bagging and vacuum infusion. Available in various widths and thicknesses – matched to different component geometries and curing temperatures.
Desiccators
For degassing small quantities of resin and moisture-protected storage of sensitive materials – available in various sizes.
FAQ – Frequently Asked Questions About Vacuum Technology
What is vacuum technology?
Vacuum technology encompasses all processes, devices, and methods based on the targeted generation and use of negative pressure. In technical terms, "vacuum" refers to any state in which the gas pressure is below the atmospheric ambient pressure. Vacuum technology is used to support processes that do not function – or function only inadequately – under normal pressure conditions, such as degassing liquids, compacting laminates, or bonding surfaces without bubbles.
Where is vacuum technology used?
Vacuum technology is found across a broad spectrum of applications:
- Fibre composite processing: vacuum infusion, vacuum bagging, prepreg processing
- Woodworking & furniture manufacturing: vacuum pressing for veneers, films and decorative surfaces
- Casting & resin art: degassing epoxy resins, polyurethane and silicone
- Electronics & precision engineering: potting of components, dry storage of sensitive parts
- Medical technology & laboratory: sterilisation, filtration, sample preparation
- DIY & model making: production of CFRP and GFRP components, vacuum forming
What are the advantages of vacuum technology?
The use of vacuum technology offers a number of decisive advantages over conventional methods:
- Uniform contact pressure across the entire component surface – regardless of geometry
- Reduction of air inclusions in the laminate or cast parts
- Higher fibre volume fraction in fibre composite components → better mechanical properties
- Lower resin consumption through controlled resin flow (vacuum infusion)
- Reproducible results through defined process parameters
- Improved surface quality through uniform compaction
- Reduction of emissions (e.g. styrene) compared to open laminating
When should vacuum technology be used?
Vacuum technology is recommended whenever:
- Air inclusions in the material must be avoided (e.g. in transparent cast parts or load-bearing structural components)
- Large-area bonds or laminates need to be compacted uniformly
- High-quality surfaces are required that could not be achieved through manual pressure alone
- Reproducibility and process reliability are a priority
- Sensitive materials need to be stored in a moisture-free environment or dried
For the ambitious home user, investing in a basic vacuum system is worthwhile from the very first larger laminating or casting project – the improvement in quality is clearly noticeable.
Why is vacuum technology so well established in composite processing?
In the processing of fibre-reinforced composites – i.e. GFRP (glass fibre reinforced polymer) and CFRP (carbon fibre reinforced polymer) – vacuum technology is so widely used for a straightforward reason: it elegantly solves the fundamental problem of hand laminating.
When laminating manually without vacuum, it is virtually unavoidable that air becomes trapped between the fibre layers. These air bubbles – known as voids or delaminations – significantly weaken the component and lead to uneven mechanical properties. Vacuum presses the layers together uniformly, drives out trapped air, and ensures that the resin fully and evenly impregnates the fibres.
The result: components with a significantly higher fibre volume fraction, better interlaminar adhesion, and superior mechanical performance – combined with reduced resin consumption. It is no surprise that vacuum infusion and vacuum bagging are today regarded as standard processes in aerospace, boat building, and motorsport – and are increasingly finding application in skilled trades and DIY contexts as well.
