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The 4 Steps to the Vacuum Impregnation Process


Vacuum impregnation seals porosity and leak paths that form during the casting or molding process. Vacuum impregnation stops casting porosity and allows manufacturers to use parts that would otherwise be scrapped. Read the following four steps to learn how porosity can be sealed through the vacuum impregnation process. 


Beginning Part
Porosity in Casting

The porosity of the cross section of this part is shown as the black squiggly lines.  
The porosity will cause:

-Pitting or blemishes on the surface
-Inability to hold fluids or gases under pressure
-Corrosion results from fluids penetrating the pores


Step 1

Casting in vacuum impregnation chamber

In the impregnation chamber (also known as an autoclave, pressure vessel or vacuum vessel) air is evacuated from the leak
path in the part by using a deep vacuum. The evacuated leak path is filled with sealant by covering the part with the sealant
and applying pressure. More energy is required to penetrate the porosity with sealant than to evacuate the air.


Step 2

Sealant recovered from vacuum impregnation


















In the recovery station (also known as drain station, centrifuge) excess sealant is recovered for reuse.


Step 3

Sealant washed from casting


In the wash/rinse station (also known as surge station, rolling rinse or pump over station) residual sealant is washed from the
part’s internal passages, taps, pockets and features where sealant is undesirable.

Step 4

Sealant cured in casting


















In the cure station (also known as standing, rolling cure or pump over station) the sealant, impregnated into the walls of the part, is polymerized in the leak path.

Final Part

Porosity sealed in casting
















As shown in purple, the porosity is fully sealed without changing dimensional or functional characteristics.

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