Maximum high-voltage and insulating resistance for transformers, restrictors and more

Electromagnetic coils are used in the automotive industry as well as in the manufacture of household appliances and in the aerospace industry. Suitable vacuum impregnation and encapsulation processes help protect the electromagnetic coils from corrosion and improve their electrical and mechanical properties.

Electromagnetic coils such as solenoids, transistors, restrictors and relays can be found everywhere, such as in household appliances, consumer electronics, medical devices and energy technology. They are also frequently employed in automotive applications and in the electronics and electrical industries. They are used for purposes such as generating or detecting magnetic fields, transforming voltages, current smoothing and as an energy accumulator.

Particularly in very challenging areas such as electromobility or aerospace, the components used, and thus the relevant electromagnetic coils, have to fulfill extremely high engineering and quality standards. This is done by impregnating or encapsulating the electromagnetic coils with a suitable impregnating or casting resin designed for electronics. Encapsulated or impregnated transformers, solenoids and restrictors not only offer better protection against environmental influences and corrosion, they also offer advantages in voltage and temperature resistance, electrical insulation, heat dissipation and mechanical stability. In some cases improved acoustic properties are relevant as well.

Vacuum impregnation and encapsulation: guaranteed bubble-free

Atmospheric impregnation and encapsulation of electromagnetic coils such as transformers or ignition coils is not enough in order to achieve the required quality results. This is due to the fact that during the impregnation or encapsulation process small air bubbles accumulate in the fine voids of wire windings. These air bubbles significantly reduce high voltage resistance, among other things, thus rendering the workpiece unusable for practical application. This could result in overheating and faults or even complete failure of the workpieces. To prevent this, it is important to prepare and feed the material as well as carry out the impregnation or encapsulation process in a vacuum.

X-ray of an electric coil potted under atmospheric conditions

Electric coil potted under atmospheric conditions with air pockets

X-ray of an electric coil potted under vacuum

Electric coil potted under vacuum

Solutions for a perfect potting process of electromagnetic coils

  • The LiquiPrep LP804 material preparation and feeding system provides an absolutely homogeneous and bubble-free potting medium. It allows for preparation in a vacuum and is therefore also the system of choice for processing humidity-sensitive potting compounds or chemically inert casting resins. The integrated temperature control also facilitates direct exertion of influence on the viscosity of the medium used.
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The actual impregnation or encapsulation process can usually be split into two or three process steps in the case of electromagnetic coils: First the workpiece is filled with the compound in the evacuated potting chamber. The prevalent vacuum provides excellent impregnation of the wire windings with the potting compound. By building up the pressure during the subsequent intermediate release of air, the medium is pressed against surface tension even deeper into the small spaces of the coils. During encapsulation, a final finishing layer is applied, which provides even coverage of the workpiece with potting compound and an optimal appearance at the same time.

  • Scheugenpflug offers a range of vacuum dispensing systems for vacuum impregnation or encapsulation of challenging workpieces such as ignition coils and transformers in a vacuum. You can find the perfect system for your application here: from our universal solution for a wide range of requirements to our power system for short cycle times.

TIP: Fast impregnation can be assured by using a dispenser, mixing tube or component heating system without limiting the longevity of the potting compound.




Armin Bindner

Sales expert

Phone: +49 9445 9564 0