From Cadmium to ZnNi: Why It Matters
For decades, cadmium plating has been the standard for protecting high-strength steels, like landing gear components, from corrosion. It’s effective, but in the U.S., cadmium is increasingly restricted because of its toxicity and the serious health and environmental risks. That’s where Zinc–Nickel (ZnNi) electroplating comes in. It’s a high-performance, cadmium-free alternative that meets critical aerospace standards. When applied correctly at 0.3–0.6 mils thickness with 12–15% nickel, ZnNi delivers excellent corrosion resistance without compromising part integrity.
Making ZnNi Work: Challenges
Switching from cadmium to ZnNi plating isn’t as simple as “dip and rinse” — it’s a whole new way of thinking about your plating line. Existing industrial facilities, often optimized for cadmium, may need upgrades to handle Zn-Ni electrolytes, precisely control temperature and flow, and accommodate specialized tooling. Without these changes, achieving uniform coating thickness and nickel content on complex aerospace parts is nearly impossible.
Even with modernized lines, the plating process is a balancing act. Think about it—current, bath flow, temperature, plating time, and cathode-to-anode ratios all interact in ways that aren’t immediately obvious. Change one thing, and the whole process can shift. Then there’s geometry. Picture a part like a landing gear bracket with recessed corners, tight cavities, and overhangs. How do you ensure every surface gets the same coating? Often, the answer lies in custom tooling, such as conformal anodes or insulating shields—but knowing exactly where to place them is both an art and a science.
Traditionally, engineers rely on experience and trial and error, tweaking settings and testing repeatedly. It works—eventually—but it’s slow, costly, and unpredictable. Imagine seeing results before a single part hits the bath. That’s the power of simulation-driven design, turning guesswork into precision and confidence.
Simulation: Turning Complexity into Control
This is where our Zn–Ni simulation workflow really shines. We calibrate our numerical models using experimental data. Hence, we can predict plating performance before a single part enters the bath—saving time, reducing costs, and improving consistency. Thanks to our extensive experience in electrochemical simulation and deep expertise in electrochemical data acquisition, we can accurately capture the behaviors that matter most for electroplating processes. This foundation is critical for reliable, predictive simulation of ZnNi plating
To ensure the simulation accurately mirrors reality, we begin by collecting experimental data in small, lab-scale cells. This includes polarization curves and plating efficiency measurements, which capture the behavior of ZnNi electrolyte under a range of conditions. The beauty of this approach is that component size doesn’t matter—even the most complex landing gear parts can be modeled reliably using data from these small-scale experiments. This makes the workflow both efficient and fully scalable.
Once collected, the data are applied as boundary conditions in Hull-Cell simulations, allowing us to verify that the model faithfully reproduces the real plating process. Only after this validation, we apply out workflow to full-size components, giving engineers confidence in the predictions before a single part enters the bath.
Nailing Uniform ZnNi Plating with Simulation
Imagine this: you’re working in CAD on a landing gear assembly and evaluating ZnNi plating for the upper rod support (see Figure 1). Before committing to tooling or running physical trials, you want to understand how the coating will actually build up on the part.
Using our simulation workflow, we evaluated ZnNi coating thickness as a function of plating time with only the main anodes active. After 24 minutes, approximately 60% of the surface meets thickness requirements (green), while under-plated regions persist in recessed features and inner bores (blue), see Figure 2. Extending the process to 30 minutes results in over-plating (red) and a reduced area within specification. This demonstrates that increasing plating time alone is insufficient; achieving uniform coatings requires modifying the current distribution through tooling or anode configuration.
To address this, conformal anodes and insulating shields are introduced to increase thickness in under-plated regions while limiting exposure to the main anodes in over-plated areas. Figure 3 shows that adding an auxiliary anode improves plating, bringing inner bore surfaces within thickness requirements.
Streamline Your ZnNi Process
Transitioning from cadmium to ZnNi is a big step—but it doesn’t have to be complicated. Our simulation workflow and expertise help engineers, materials scientists, and production teams achieve high-performance, uniform coatings with confidence. Contact us to learn how our ZnNi simulation workflow can streamline your process, improve coating quality, and support safer, greener manufacturing practices.
Authers:
Bashir Alnajar & Julio Mendez