Porosity Sealing - Vacuum Impregnation Methods

Vacuum Impregnation Methods

There are a variety of methods that can be used to impregnate metal parts. The method chosen depends on a part requirements, specifications and sealant that will be used. All methods used are effective and once porous metal parts are sealed and cured, they will be sealed indefinitely.

• Dry Vacuum/Pressure (DVP): This is the most complex and effective method of impregnation. The DVP cycle requires two separate tanks, one for processing the part and the other for storing the sealant. This process is best used for metal parts that contain extremely small, microscopic pores that may be invisible to the naked eye. The process steps are as follows:

1. Parts are loaded into a process basket and placed into a processing tank.
2. A vacuum is activated in the process tank to remove all air, including air within the pores of the parts.
3. Sealant is transferred from storage tank to the processing tank and the entire basket of parts is submerged.
4. Vacuum is released and desired pressure is added to the process tank using compressed air. This pressure will help the sealant enter the pores.
5. After desired amount of time, the pressure is released and the sealant is drained back into the sealant storage tank.
6. The processing basket full of parts is removed from the processing tank and all parts are washed and final processed according to the metal material and specifications of the part.

• Wet Vacuum/Pressure (VP): This cycle requires only one tank that contains the desired sealant. The process steps are as follows:

1. Parts are loaded into a process basket and placed into the sealant tank.
2. Vacuum is activated in the sealant tank to remove all air, including air within the pores of the parts.
3. Vacuum is released and desired pressure is added using compressed air.
4. Pressure is released from the tank.
5. The processing basket full of parts is removed from the tank and all parts are washed and final processed according to the metal material and specifications of the part.

• Wet Vacuum (WV): This cycle is the quickest impregnation method. It requires only one tank with the desired sealant. The process steps are as follows:

1. Parts are loaded into a process basket and placed into the sealant tank.
2. Vacuum is activated in the sealant tank to remove all air, including air within the pores of the parts.
3. Vacuum is released and tank is vented to atmospheric pressure.
4. Parts are soaked in the sealant for desired amount of time.
5. The processing basket full of parts is removed from the tank and all parts are washed and final processed according to the metal material and specifications of the part.

Henkel Corporation (2005). Porosity Sealing by Design. pp. 9–10.