What is the most economical way to degas the material?
Air bubbles in the potting material can lead to problems depending on the application requirements. If they get into the dispenser, they may falsify the dispensed quantity and the mixing ratio. This results in irregular production results and even rejects. However, various technical solutions make it possible to reduce the formation of air bubbles to a minimum. To retain a degassed material, preparation under vacuum is essential. However, it must be noted that some materials can lose important constituents by evaporation due to their partial pressure if the vacuum is too high.
Negative pressure / vacuum
A common method of removing air bubbles from the material is vacuum degassing. This involves temporarily placing the material in a vacuum. According to William Henry's law, the partial pressure of a gas over a liquid is proportional to the gas concentration in the liquid. Evacuation to only a few millibars lowers the partial pressure and thus the gas concentration in the material. The dissolved gases are then removed by a vacuum pump.
Adequate heating can reduce the viscosity of the material and thus accelerate the degassing process. To avoid re-inclusion of air, all fittings, material lines, pumps and valves must be hermetically sealed or vacuum-tight.
An efficient preparation unit removes air bubbles as well as dissolved gases from the respective potting materials. By increasing the material surface area, which can be achieved by thin layer degassing, dissolved air is transported faster to the surface of the potting material where the degassing effect takes place. A surface renewal of the potting material, e.g. by means of a suitable agitator, additionally accelerates the degassing process.