Reasons for the Blackening of the Machined Surface of Automobile Castings

Update:11 Mar 2022

Most of the materials used in automobile casting processing are metals and aluminum alloys, which have good plasticity, but some friends will find that aluminum-magnesium alloy die-castings are easy to turn black during use. What is the reason? Let's find out together.

1. The process design is unreasonable.

Improper handling of aluminum alloy die castings after cleaning or pressure inspection creates conditions for their blackening and accelerates the formation of mildew.

2. Improper warehouse management

Aluminum alloys are amphoteric metals and can react with acids and bases.

3. Internal factors of aluminum alloy

Some aluminum alloy die-casting manufacturers do not do any cleaning treatment after the die-casting machine is processed, or simply rinse with water, which cannot be completely cleaned, and residues will remain on the surface of die-casting aluminum. These residues It will speed up the rate of blackening of die castings.

4. External factors of aluminum alloy

Aluminum is an active metal, which is prone to oxidative mildew or blackening under certain temperature and humidity, which is determined by the characteristics of aluminum itself.

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