The Reasons that Can Cause Powder Metallurgy Gears to Produce Pitting

Reasons for powder metallurgy gears to produce pitting:

Powder metallurgy products are prone to rust and corrosion due to their frequent contact with air. This is especially true in coastal and humid areas, where the humidity in the air can exacerbate the corrosion. In some cases, not only the surface of the product is affected, but even the surface of the internal connecting pores can also be corroded, seriously affecting their performance and even causing them to be scrapped. 

To prevent rust on powder metallurgy products, there are several measures that can be taken: 

1. Rust prevention measures for iron powder: Since purchased iron powder is a solid powder, there are many air pockets between the powder particles. If humid air is introduced, the iron powder can rust and solidify quickly, rendering it unusable. Therefore, the purchased iron powder should be stored in a sealed thick plastic bag, with a desiccant installed inside, and placed in a thick woven bag for easy lifting. 

2. Storage of iron powder: When storing iron powder in a warehouse, the principle of first in, first out must be followed. After mixing, the iron powder should be packed into thick plastic bags according to the packaging method at the time of purchase, to prevent oxidation. It should also be placed on a wooden pallet, with a usage time of no more than 3 days. 

3. Use of iron powder pressing technology: In the production process of synchronizer hubs, iron powder can be mixed with sleeve rings as necessary. However, do not take out all the iron powder at once just because there are many tasks; instead, the stock of mixed iron powder between processes should be strictly controlled. 

4. Storage of synchronizer hub blanks: The strength of synchronizer hub blanks is low, making them easily damaged, so they must be handled with care and placed onto plastic pallets for transport. If the blanks are sintered and pressed within 48 hours, additional external protective packaging is not necessary. If this time frame is exceeded, the plastic film should be wrapped and sealed on the transfer car to prevent moisture from entering. 

5. Rust prevention testing methods: After sintering, 30# machine oil should be used when finishing powder metallurgy hub machining. Immediately after sintering, rust-proof oil should be used for dipping and powder metallurgy gears should be finished with 30# machine oil. For combustion bonding, vertical dipping with WD40 rust-proof oil is recommended, followed by finishing powder metallurgy gears with 30# machine oil.