In order to properly seal porosity, parts must be clean and dry. If any residual fluids or debris are on the part, then the following problems may occur.
- Increase TAKT time
Any residual fluids will need to be boiled off in the vacuum chamber. When water boils, it expands to approximately 1,700 times. That expansion means there is more volume for the vacuum pump to evacuate from the vessel, which takes time. In addition, if the water is in the part’s porosity, then the evaporation process could take several seconds more than evaporating from the surface. A few additional seconds may not sound like a lot of time. But this additional time compounds and can cause production delays with large production volumes.
- Risk of Contamination
Residual fluids and solids on the part can contaminate the sealant. The impurity of sealant can inhibit the sealing of future parts. Vacuum impregnation is a controlled process. Sealant contamination will cause the vacuum impregnation process to not be controlled.
- Risk of Parts Not Being Properly Sealed
The vacuum cycle may not fully remove part debris and fluids. These will go into the porosity once the vacuum is released. As a result, the sealant will not be able to properly seal the porosity. The parts may not pass leak test since the porosity is not properly sealed due to the contamination.
When considering or preparing for vacuum impregnation, be sure to account for cleaning and drying of parts prior to impregnation. This is an essential prerequisite. Ensuring that that impregnation system receives clean, dry parts will help guarantee that they are sealed efficiently and effectively.
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