Vacuum is also generally known as “under-pressure”. In the physical definition, it is also said that matter is absent in a space. In vacuum technology, the respective unit is p absolute. The unit most frequently used for the vacuum is millibar (mbar).
Absolute means that the pressure is stated proceeding on the standard pressure 1013 mbar as a basis. Accordingly, the absolute vacuum is 0 mbar. If the pressure is indicated as a relative pressure, the absolute vacuum is -1013 mbar, the atmospheric pressure is 0 mbar. The differential pressure is the pressure between two measuring points. See the diagram below for further explanation.
In vacuum technology, the pressure is usually specified as absolute pressure.
Various vacuum ranges are differentiated, namely:
low vacuum (GV) 1000 – 1 mbar
medium vacuum (FV) 1 – 10–3 mbar
high vacuum (HV) 10–3 – 10–7 mbar
ultra-high vacuum (UHV) 10–7 – (10–14) mbar
The vacuum systems by Diener electronic usually operate in the low and medium vacuum ranges. For special applications, high-vacuum systems can be implemented as well.
In which fields can Diener vacuum systems be used?
Vacuum systems by Diener electronic are used in research and development as well as in series production. Some typical applications are described in the following:
Vacuum degassing
With vacuum degassing, volatile substances such as solvents or moisture are removed in a controlled process. Many materials need degassing to eliminate the negative effects of the volatile substances.The following negative effects may occur for example: bad smell, loss of adhesion when gluing, painting or coating. For degassing, the parts are exposed to a defined vacuum. Often, the vacuum is run in ramps.
The graph shows an exemplary outgassing process with pressure ramps. The image is an idealised representation. In practice, the system needs some seconds to reach the next pressure ramp. The respective pressures are maintained for a certain period of time before approaching the next ramp. To accelerate the process, the chamber is heated in most cases. Heating the Diener electronic vacuum chambers made of aluminium extruded sections is particularly easy and low-cost.
See the following example of a typical production process:
1. Degassing of the components with vacuum
2. Activation of the components with plasma
3. Coating/gluing/painting/filling of the components
Vacuum drying
The process used in so-called vacuum drying is almost identical with the degassing process. Vacuum drying is used to dry products saturated with liquids such as water or solvents. The major benefit of vacuum drying is the low temperatures. The lower the pressure, the lower the temperature at which water passes from the liquid to the vapour phase.
This ensures very gentle drying of high-value and sensitive products at low temperatures.
Manual vacuum casting
Another variety of vacuum degassing is manual vacuum casting. Bubble-free casting is mandatory for high-value and heavily loaded components. With manual vacuum casting, the parts are cast at atmospheric pressure. Next, they are exposed to gas in a vacuum chamber. This makes premium-quality bubble-free manual casting possible. This is of advantage above all for small series production as well as for research and development purposes. With manual vacuum casting, running suitable pressure ramps is a precondition for achieving optimum results. It is also possible to use special casting compounds not suitable for standard casting systems.
Height simulation
Nowadays, suitability for air transport is a mandatory for many components. While there is pressure equalization in the cargo holds of aircraft, it cannot completely compensate for the pressure fluctuations. The pressure can fall below 800 mbar abs. In a Diener electronic test plant, the components can be exposed to a pressure simulation test. Also significantly lower pressure levels can be simulated to test the behaviour for example during a pressure drop.
Some components such as electric motors are also operated outside of pressure cabins. Perfect functionality must be ensured there. With suitable cable feedthroughs, these motors can be operated inside the vacuum chamber.
Components used in space must be able to withstand even much higher loads. For them, pressures of 10-6 mbar and smaller must be simulated. To achieve pressures as low as this, a turbo molecular pump with a suitable pre-pump is required.
What types of vacuum systems are there?
Generally, the following questions must be answered:
- In which pressure range do you intend to work? (coarse, fine, or high vacuum)
- What is the permissible deviation from the setpoint pressure? (How accurate does the pressure regulator have to be?)
- Do you intend to run pressure ramps/time curves?
- Do you need heating?
- Will there be outgassing of substances which are harmful to the pump or the environment?
- What is the goal of the application?
- Do you need electrical bushings?
- Should the system be designed as a stand-alone or a tabletop unit?
With your answers to these questions, we will be able to design a system tailored to your requirements.
FAQ Frequently Asked Questions
What are the advantages of vacuum systems from Diener electronic?
Diener electronic offers you:
- 30 years’ experience in vacuum and plasma technology as well as process development
- the ideal chamber type, whether aluminium, stainless steel or glass
- customised chamber sizes
- vacuum pumps suited to the application
- in-house developed control systems
- Pre-configured process sequences,
- Quality assurance through documentation of pressure, temperature and time profiles
- Automation partners enable integration
How can a vacuum be measured?
When selecting the appropriate vacuum measuring instrument, a number of questions need to be answered:
- What tolerance should the measuring instrument operate within?
- Which pressure range is relevant to the process?
- Might it be necessary to combine several measuring instruments?
In our systems, we mainly use Pirani sensors and capacitive pressure gauges. We would be happy to advise you on selecting the appropriate pressure measurement solution.
What are the advantages of vacuum drying without heating?
Diener electronic’s vacuum drying process utilises the lower boiling point under vacuum to degas temperature-sensitive materials. It is a gentle process, particularly suitable for electronic components.
What are the advantages of vacuum drying with heating?
If necessary, the vacuum chamber can be heated. The advantages of heating include a shorter drying time, uniform drying and the ability to process larger quantities of material.
What are pressure ramps in vacuum degassing?
Uncontrolled foaming or even overflow of the material is prevented by individually tailored pressure ramps.
Can solids be degassed?
Yes, odours, outgassing or contaminants can be removed before further processing, depending on the nature of the material.
What can be achieved with an altitude simulation?
The air pressure in a vacuum chamber is set to the expected flight altitude. The resulting tests – such as leak testing, material behaviour and the stability of electronic and mechanical components – play a major role in ensuring operational reliability.
Which sectors benefit from a height simulation?
Altitude simulators from Diener electronic are successfully used in the following sectors
- Electronics
- Battery technology
- Aviation components
- Packaging industry
- Aerospace
- Automotive
- Electronics
- Medical technology
- Sensors
- Research and Development
To what extent can Diener electronic tailor its vacuum systems to individual requirements?
Every process has different requirements in terms of chamber size, final pressure, process duration, heating capacity, cycle time and automation. That is why Diener electronic develops each system in collaboration with the customer and tailors it perfectly to the specific product and the desired process. Systems can be configured for applications ranging from rough vacuum through to fine vacuum and high vacuum. The appropriate vacuum pump is used for this purpose.
Diener electronic’s vacuum systems can usually be integrated into existing production lines.
What maintenance and safety measures need to be observed?
Regular maintenance of the vacuum pump, seals, sensors and filters ensures consistently high system availability and process reliability. Vacuum systems must only be operated in accordance with the operating instructions. Regular inspections of pressure vessels, seals and safety devices contribute to safe operation. Servicing must only be carried out by trained personnel from Diener electronic GmbH & Co KG.
