Anodizer

Anodizer can refer to either the equipment used to perform anodizing or the person who conducts the process. Anodizing is an electrochemical method that converts the surface of a metal into a durable oxide layer by making the workpiece the anode in an electrolytic cell. The oxide is integral to the base metal and its thickness is controlled by current, time, electrolyte, and temperature. The most common metal treated is aluminum; magnesium and titanium are also anodized. The most widely used electrolyte for aluminum is sulfuric acid; historically chromic acid was used but is being phased out due to environmental concerns. Other electrolytes include oxalic acid for certain decorative finishes.

Process and properties: The resulting oxide film thickens with controlled current and time. For aluminum, standard (Type II) coatings typically range from about 5 to 25 micrometers; hard anodizing (Type III) can reach 25 to 100 micrometers or more. The oxide in aluminum is porous after formation and is typically sealed to improve wear and corrosion resistance. Color can be natural gray, or achieved by dyes in Type II processes, or by interference effects in titanium anodizing to yield a spectrum of colors.

Equipment and procedure: Anodizing uses tanks with an electrolyte solution, a powered electrical supply, racks to suspend parts, filtration and cooling. After anodizing, parts are rinsed and sealed to close pores. Safety concerns include handling caustic electrolytes, hydrogen production, and proper ventilation.

Applications: Used for architectural hardware, consumer electronics enclosures, automotive parts, aerospace components, and more, where corrosion resistance, wear resistance, and color control are desirable.