What factors influence the cost of arc anodizing the most?
Primary Cost Drivers in Arc Anodizing
The cost of Arc Anodizing is influenced by a combination of technical process parameters, part characteristics, and operational factors. The most significant influences are directly tied to the substantial energy and time required to grow the thick, functional ceramic coating.
Process Parameters: Coating Thickness and Time
This is the most direct cost factor. The relationship between coating thickness and processing time is not linear; achieving greater thickness requires exponentially longer process times due to decreasing growth rates as the insulating layer thickens.
Target Thickness: A standard specification of 50 µm (2 mils) will have a baseline cost. Specifying a thicker coating for more demanding applications (e.g., 75-100 µm) will significantly increase the cost due to the extended time the part must remain in the electrolytic bath under high electrical load.
Electrical Power Consumption: The process operates at high voltages and currents for extended periods. The electrical energy consumed is a major component of the operational cost, and longer cycle times directly translate to higher energy bills.
Part Geometry and Surface Area
The "bill" for arc anodizing is largely based on the total surface area being coated.
Total Surface Area: A larger part, or a batch of smaller parts with a high collective surface area, will consume more electrolyte and energy than a single, small component.
Geometric Complexity: Parts with deep recesses, blind holes, or complex internal channels pose a challenge. The process has a "throwing power," but ensuring a uniform coating thickness in hard-to-reach areas may require specialized fixturing, longer processing times, or result in higher material usage, all of which add to the cost.
Substrate Material and Preparation
The choice of aluminum alloy impacts both the process efficiency and the final result, influencing cost.
Alloy Compatibility: As previously discussed, a A360 alloy anodizes more efficiently and uniformly than a high-silicon alloy like A380. If a poor-anodizing alloy is used, achieving a satisfactory coating may require longer times or result in higher part rejection rates, increasing effective cost.
Surface Condition: Parts requiring extensive Post Machining or cleaning to remove contaminants, oxides, or release agents from the die casting process will incur additional preparation costs before anodizing can even begin.
Ancillary Processes and Quality Assurance
Masking: If specific areas of the part must remain uncoated (e.g., for electrical contact or precision threads), labor-intensive masking is required, adding cost.
Quality Control and Testing: Meeting stringent specifications for high-reliability industries necessitates rigorous Post Process inspection. Costly and time-consuming tests like cross-sectional analysis, salt-spray testing, and hardness verification contribute significantly to the overall cost but are non-negotiable for critical applications.
