Vacuum Pressure Impregnation

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Vacuum Pressure Impregnation Process

What is Vacuum Pressure impregnation ?

Vacuum Pressure Impregnation (VPI) is a process that uses vacuum and pressure to seal porous materials with varnish or resin. The process is used primarily for high-voltage motors and generators to fill gaps in materials to create a void-free insulation in various devices. Industrial electromechanical equipment is designed for durability to provide reliable function and increased longevity, but age, temperature, and environmental factors can degrade porous metals over the time. The process of impregnation seals porous materials with varnish or resin, improving the function and longevity of the equipment.

Vacuum Pressure Impregnation Process:

  • We specialize in vacuum pressure impregnation, which is more effective than traditional dip-and-bake methods and is better suited to high voltage motors and generators. Our basic vacuum pressure impregnation motor repair process comprises several steps.


  • We place the equipment in an oven that heats the equipment and allows moisture to evaporate. This helps the resin better penetrate the material.

Dry Vacuuming

  • We remove the equipment from the oven and place it into a vacuum chamber, which removes air and any remaining moisture.


  • We increase pressure within the chamber using dry air, nitrogen, or other gases. This allows for even deeper penetration of the resin.


  • We then vent the pressure, drain the chamber of excess resin, and remove the part.


  • Finally, the equipment is placed into an oven to cure the resin.

Benifits of VPI:

  • In traditional impregnation, varnishes can lose up to 50% of their volume in the curing process. The reduced volume leads to air pockets and gaps, making it more susceptible to damage and wear. The vacuum used in a VPI creates a more solid structure that can withstand:

    1. Leaks
    2. Cracks
    3. Corrosion
    4. Moisture

    VPI also accommodates longer insulation life and greater heat dissipation. Vacuum pressure impregnation is a more cost-effective solution as it extends the lifetime of products while saving energy.

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