We would recommend that for most normal operating conditions PSM rings should be reimpregnated after approximately 5,000 hours running. However in some instances, such as acrylic spinning, reimpregnation could be necessary after 1,000 hours running.
The reimpregnation process can be achieved by various methods. An automatic vacuum impregnation machine is used to impregnate rings during manufacture. We would normally recommend this procedure for large installations of PSM rings. For most mills an alternative would be to immerse the cleaned rings for two hours in a tank filled with recommended oil that has been heated to a temperature of 75 to 80°C. After two hours soaking in the hot oil, no more air bubbles should be seen rising to the surface, ensuring that the absorption of the oil is complete.
The rings should then be carefully removed and immersed for 30 minutes in a tank containing cold recommended oil to allow them to cool.
When the rings are removed, they are ready for re-wicking as detailed in the wicking section.
Impregnation Time Chart
1 = Under vacuum at approx. 20 Torr / 20°C
2 = At temperatures between 70 and 80°C
3 = At room temperature, approx. 20°C