Machining Technology of Powder Metallurgical Parts

Many powder metallurgy mechanical parts have grooves, transverse holes, threaded holes, etc. in the vertical pressing direction, as well as high dimensional accuracy and positional tolerance accuracy (coaxiality, perpendicularity, etc.), making it difficult or costly to achieve through molding methods. So cutting is usually used to achieve this, which is still economically accounted for.

The cutting process of powder metallurgy parts should pay attention to the following two issues:

1. The working surface of powder metallurgy parts (such as oil bearing inner holes, etc.) should not be processed by grinding or other methods. Due to the possibility of abrasive particles entering the voids during the grinding process, the lubricating oil contained in the parts is less likely to seep out during operation, affecting their service life.

2. When cutting powder metallurgy parts, try not to use coolant as much as possible. In special circumstances (such as tapping), light vegetable oil can be used as the cutting fluid. If it is necessary to use coolant (such as saponification solution for grinding, etc.), the parts must be cleaned after processing. High boiling hydrocarbons (such as BP ethane, etc.) can be used for cleaning, or ultrasonic cleaning can be used. After cleaning, dry the parts at a temperature above 100 ℃ to remove any residual coolant in the gaps. Then vacuum immerse the parts with anti rust oil to prevent rusting.

For general powder metallurgy parts that require machining processes, an appropriate amount of cutting agent is added when mixing raw materials to prevent defects such as sticking, overheating, and slow feed during mechanical processing. The main machining methods for powder metallurgy parts include turning and boring, planing and milling, drilling and reaming, tapping, grinding, and extrusion.