After hard anodized, 50% of the oxide film infiltration into the aluminum alloy, 50% attached to the aluminum alloy surface, so outside sizes will be larger, and inside holes sizes will be smaller.
First: Differences in operating conditions
1. Temperature is different: common anodized finish temperature is 18-22 ℃, if there are additives temperature can be 30 ℃, it’s easy to arise powder or pattern if temperature is too high; hard anodized finish temperature is generally below 5 ℃, generally speaking lower temperature, the higher of the hardness.
2. Concentration is different: common anodized concentration is about 20%; hard anodized is about 15% or less.
3. Current / voltage is different: common anodized current density: 1-1.5A / dm2; hard anodized: 1.5-5A / dm2; common anodized voltage ≤ 18V, hard anodized sometimes up to 120V.
Second: differences in film performance
1. Film thickness: the thickness of common anodized is thinner; hard anodized film thickness > 15μm.
2. Surface state: the common anodized surface is smooth, while the hard anodized surface is rough.
3. Porosity: common anodized porosity is high; and hard anodized porosity is low.
4. Common anodized film is basically transparent; hard anodized film is opaque because of film thickness.
5. Applicable to different occasions: common anodized mainly used for decoration; hard anodized finish generally used for wear-resistant, power-resistant occasions.
Above information for reference only. Any comment was welcomed.
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Post time: Jan-07-2021