Optimizing Ecoat With Zirconium Pretreatment

Q: How can e-coat bath performance be optimized for use after a zirconium pretreatment?

A. In today’s metal finishing environment, it can seem like there is constant pressure to do more with less. How can you meet the competing demands of cost savings objectives, regulatory changes, customer specification requirements, and unstable labor markets and supply chains? Can zirconium pretreatment be a part of the solution?

There are many great reasons to decide to switch from conventional phosphate-based pretreatment to a zirconate alternative. Zirconium pretreatments provide a variety of benefits to your paint line.

Simplify your line footprint: A high-quality zirconium coating should be able to produce results that are comparable to a conventional zinc phosphate line in a much smaller footprint. Rather than the seven stages required for most zinc phosphate systems, zirconate systems can have your part ready for presentation to e-coat in as few as four stages. Fewer stages mean you can achieve utilities savings while increasing throughput.

Simplify preventive maintenance: Zirconium pretreatments don’t produce phosphate sludge, so you don’t have to boil out your tanks. This means you can enjoy more uptime and increase productivity.

Simplify EHS compliance: Phosphate waste is typically classified as HAZMAT and is therefore difficult and costly to dispose of. When required, zirconium pretreatment baths are easier to crash and dispose of. Of course, work with your EHS team to comply with your local regulatory requirements.   

Reduce scrap: Like e-coat, zirconium coatings are self-limiting. That means that once you achieve your coating thickness, no additional zirconium oxide is deposited on the surface of your substrate. If you have a line stoppage, you may be able to process any parts stuck in your pretreatment bath without any rework.

Meet your spec: Zirconium pretreatments can meet even your toughest spec without the operational costs and environmental impacts of traditional iron- or zinc-phosphate systems.

So you’re ready to get the operational and EHS benefits that zirconium pretreatments deliver, but what will that mean for your e-coat bath?

Maximizing performance

Here are a few considerations to maximize your e-coat performance as you make the change:

Consider optimizing your line speed. Because zirconium coatings produce a uniform, very thin zirconium oxide layer instead of a porous, uneven zinc phosphate layer, the substrate will likely have higher conductivity. You may be able to achieve the same film build in less time.

Consider increasing throw power. If the part geometry has recessed areas or a cylindrical structure, the zirconium pretreatment may have a higher DFT, evaluating your throw power and strategically placing anodes will ensure that you have the coverage you need even in hard-to-reach places.

Consider anode placement and hang method. Assess your anode placement to maximize film build as you change your line speed and throw power. Check for air pockets and areas of lower coverage as starting points to evaluate any changes.

Consider modifying your e-coat bath parameters. Take a holistic look at your voltage, throw power, temperature, and film build parameters, such as pH, solids, and P-B ratios to get the most consistent results on your substrate.

Consider your cleaner. Start with the cleaner tank to ensure your parts are truly ready for pretreatment and e-coat. Can you pass a dyne test and are the parts water break free? If the parts aren’t clean, you run the risk of contaminating your zirconium and e-coat baths downstream. While you’re evaluating cleaners, review your supplier’s SDS and TDS information to make sure their formulas aren’t hiding phosphates in the cleaners.

Preventive Maintenance

As always, if you don’t schedule your preventive maintenance, your line will schedule it for you!

Perform bath maintenance according to the operating instructions provided by your pretreatment and e-coat suppliers. Check nozzles for clogs and alignment throughout your paint process. Make sure your rinse stages are working properly and producing appropriate water pressure. Run routine checks to ensure your oven is properly curing your parts after they are e-coated.

Consider your Tech Service Partner

Evaluate the support you get from your pretreatment and e-coat suppliers to ensure you have the resources you need in the lab and on the line. Your supplier should help you validate the performance of your adjustments and make sure you continue to meet your toughest specifications.

You can achieve all the operational and EHS benefits of zirconium pretreatments in your e-coat paint line. Like any change in a manufacturing environment, you will need to fine tune your process to maximize your results over time. Zirconium pretreatment can be the perfect piece to balance the competing demands of local regulators, difficult specs, and total cost of use objectives.