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LM5 Alloy refuses to Anodize

HELP REQUIRED!
I need to know the process of anodizing LM5 aluminium alloy which I am using for pressure die-cast process. The recent problem which I faced was blackening of the part, it was not able to anodize, not even a single micron. it turns black, as if there's some kinda carbon formation on it, Can anybody please help in overcoming this problem, I have a big consignment to be delivered by the end of this month, so please do help me out..

Navneet
- Surat, India
2005

Is your rectifier plugged in? Sorry, just kidding. This alloy should anodize very well. Could you have die lubricant on the surface of the part, preventing good wetting with the electrolyte?

Chris Jurey, Past-President IHAA
Luke Engineering & Mfg. Co. Inc.

Wadsworth, Ohio

2005

You didn't say what kind of dye you were using but my experance is. If your castings are turning black then you have some type of anodize on surface. When you anodize you get pores in the surface and that is what holds the dye. Did you check surface with a multi-meter after process.

Also different alloys look different after anodizing.

Chris Snyder
plater - Charlotte, North Carolina
2005

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