In case of plants with single stage degassing working vacuum is 3 to 10 torr and in case of plants with two stage degassing system working vacuum is 0.1 to 0.3 torr. Plants with 0.01 torr can be also offered
According to the principle of Impregnation, activated resin is trickled in a thin jet on to the rotating preheated winding. The resin immediately gets heated and its viscosity is reduced. Due to the rotary motion of the winding the resin gets distributed evenly inside the winding without any drain loss. The heated winding accelerates the gelling and curing of the resin.
According to the size of the job to be impregnated and production rate, three models have been established. 1) Indexing table type varnishing machine, 2) Batch type Horizontal table type varnishing machine, 3) Conveyorised system for varnishing.
Trickle impregnation process is especially characterized by its low energy cost due to a very short cycle time compared to Dip varnishing or the Vacuum impregnation. Compared to the Dip and bake varnishing method, which uses varnishes containing 50 to 55% solvents and the impregnation cycle of 8 hrs to 24 hrs. Trickle impregnation cycle times are substantially low to the tune of 20 min. to 40 min. Hence it is quite evident that trickle impregnation process offers the most cost economical answer to the impregnation process.