Imprex has been designing, engineering, manufacturing, and installing Vacuum Pressure Impregnation (VPI) equipment since 1958. Our VPI systems are installed all over the world in applications from electronic equipment and coil windings to motors, generators, transformers, automotive parts, pumps, and more.

Imprex pressure vessels are built to ASME Code.


Wherever castings of any metal must withstand hydrostatic, hydraulic, or pneumatic pressures, then they can be Imprexed.

Metal Casting Impregnation

Impregnation of metal casting has become a standard finishing system and Imprex has led the way since 1958 in sealing porosity through VPI systems, using resin which solidifies inside the pore.

Powdered/Sintered Metal Impregnation

Porosity is always present in powdered or sintered metal parts. Imprex specializes in supplying easy-to-control, economical products that are effective for sealing powdered metal components.

Imprex-impregnated P/M parts have these advantages:

  • Excellent Machinability - Porosity in powdered metal causes chatter, resulting in reduced tool life. When porosity is filled with Imprex resin, chatter is eliminated and tool life is extended up to 1000%.
  • Excellent Plateability - The porosity in powdered metal will absorb oils, deburring fluids, pre-plating cleaners, and acids that can later cause spotting on the plated surface. Impregnation fills voids and eliminates spotting.
  • Pressure Tightness - Interconnected porosity can cause leakage of gases, fuels, hydraulic oils, and more through the wall section of the part. Imprex impregnation fills this porosity eliminating leakage.

Electronic Component Impregnation

Just as with porous castings, electronic components need to be protected from moisture, humidity, solvents, fluxes, and corrosive agents. The Imprex process seals leak paths between metal leads/wires and the molded plastic from the inside out.