October 23, 2010

Anodizing Energy Sources

Anodizing energy source use direct current electric source (DC) or may use pulse anodizing with the pulses gap just in millisecond. If the pulses of electric current to big, anodizing product results are too bad, big pores and the finished product can not stand for long time. Processing time to produce anodizing product with 20 μm of oxide thickness is about 60 minutes.

Using pulse current should be optimizing, pulsating between two value of current density work because it gives the aluminum surface time to recover during low current density periods. The length of periods should be 10 – 240 second, because if two different dissolution mechanisms are taking place during anodizing.

Oxide film that produce on anodizing process will no longer can transfer electric current, so constant current during the anodizing process will result in an increase voltage due to the growing of aluminum oxide layer. The increasing of voltage will directly proportional to current density.

Pulse current is use alternating current (AC) that passes through rectifier. To apply this method should be understand that rectifier that use on this process must able to stand for current density until 20 A/dm2. This condition are very important because need to gain a basic understanding of process, but also need to maximize the expected advantages of pulses anodizing in daily production.

To optimize of current source of aluminum anodizing process, the tool should be possible to switch from DC to pulse anodizing and also interchangeable between pre and post anodizing processes. Flow process for pretreatment, racking and rinsing process should not become a bottleneck.