How does coating thickness affect arc anodizing pricing?

The Primary Driver of Cost: A Non-Linear Relationship

Coating thickness is the single most significant factor influencing the cost of Arc Anodizing. The relationship is not linear but exponential; doubling the coating thickness can often more than double the cost. This is due to the fundamental physics of the process, where the growing ceramic layer acts as an electrical insulator.

Process Time and Energy Consumption

As the coating thickens, its electrical resistance increases dramatically. To continue driving the plasma discharges necessary for coating growth, the power supply must continually increase the applied voltage and/or current. This results in two major cost impacts:

• Longer Cycle Times: Achieving a 25 µm coating might take 30 minutes, but reaching 50 µm could require 90 minutes, and achieving 75 µm might take over 180 minutes. The growth rate slows considerably as thickness increases.

• Substantial Energy Use: The process requires a high amount of electrical energy. Extending the process time directly multiplies the energy cost, which is a primary operational expense.

For context, a standard specification might call for a 50 µm (2 mil) coating. Requesting a thicker coating for extreme wear resistance (e.g., 75-100 µm) will incur a significantly higher price due to the drastically extended processing time and energy required to penetrate the already-formed insulating layer.

Interaction with Other Cost Factors

Coating thickness does not act in isolation; it amplifies other cost variables:

• Substrate Material: As discussed in alloy compatibility, achieving a specific thickness on a difficult-to-coat alloy like A380 will be more expensive and time-consuming than on an optimal alloy like A360.

• Part Geometry: Maintaining a uniform thick coating on a complex part with deep recesses is challenging, often requiring even longer cycle times or resulting in higher rejection rates.

• Quality Assurance: Thicker coatings often come with stricter performance requirements. The Post Process validation, such as cross-sectioning for thickness verification and extended salt-spray testing, adds non-trivial cost.

Practical Implications for Design and Costing

Therefore, during the die castings Design service and die castings Engineering phases, it is critical to specify the minimum coating thickness required for the application. Specifying an unnecessarily thick coating based on a "more is better" assumption will lead to avoidable and significant cost increases without a corresponding performance benefit.