Anodizing Problem

Please tell us the metal, the prep, and the process spec.

Really,

You've got to give some information.

From what you say "its will remove in layers form like paint remove form walls" I would presume that the base metal of the alloy accepts anodizing.

If the anodising is done on an alloy that cannot be anodised it would come off like a powder.

I couldn't say without seeing it, if it is a conventional anodising, hard anodising or chrome anodising. In any case if the coat peals off it is due to an excess of current during the anodising process. This defect is quite common in hard anodising where you work with high amperage.

There are other processes now used on aluminium , the most common is sputtering. In this case the coat (which is not aluminium oxide) can peal off if the metal if it does not have a good preparation for anchorage.

Anodizing is usually referred to Aluminium product to be anodized to form a layer of Oxide Al2O3.

Maybe you are Electroplating: Covering a metal with another metal by electrolysis.... this can have layers that will peal off if the process was not prepared properly etc.

Reading you message again I understand that you are the anodiser. Calling the object a part I believe it is a small component. If it is die cast or gravity cast there is little I can suggest without much more detail on the alloy. If it is extruded in 6063 or similar you have a problem of the so called super oxide. It can be due to

• Too high a current density (especially on components you should not exceed 1.5 Amps/dm2)
• Temperature of the anodising tank is too high. (should not exceed 22°C without additives)
• Too many microns (on an architectural type anodising you should not exceed 25 microns)
• Your sealing is no good.( a PH too high will attack the base metal and basically strip the oxide)

Hope this helps.