Heating oil immersion: Soak the cleaned sintered parts in hot oil at 80~120℃ for 1 hour. As the product is heated, the air in the connected pores expands. Part of the air is expelled. After cooling, the remaining air shrinks again, drawing the oil into the pores. Because the hot oil has good fluidity and high lubricity, more oil can be immersed into the product. The efficiency of the oil immersion method is higher than that of ordinary oil immersion.

Vacuum oil immersion: Put the cleaned sintered gears into a vacuum box, seal and evacuate to -72 mm Hg, then put oil into the vacuum box, and then heat it to 80 ℃ for 20 to 30 minutes. Since the air in the connected pores of the article is drawn out, the oil can soak into the article within 10 minutes. This method has high oil immersion efficiency and high speed.

Ordinary oil immersion: Put the cleaned sintered structural into the oil (usually 20~30 oil) to soak, and the oil is under the action of the capillary force of the product. Immersion into the pores of the product. This method has low oil immersion efficiency and long oil immersion time, which takes several hours. It is used in products with low oil content.

The operating principle of the oil immersion process of powder metallurgy products is that the iron-based oil-containing bearing is sintered and then immersed in oil, and the powder metallurgy lubricating oil enters the pores of the product. When the shaft rotates, dynamic friction occurs with the sleeve to generate heat; the temperature of the bearing rises, and the oil expands when heated; it flows out from the pores to automatically supply oil between the shaft and the sleeve, and the formed oil film plays a role in lubricating and reducing friction.