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E-Coat Pre-Treatment

One of the many reasons Burkard Industries stands out as an e-coating industry leader is because of the unique 14-stage pre-treatment process that we put parts through as part of our e-coating services.

We believe that with all finishing operations, the most important step is pre-treatment of the parts. If parts are not pre-treated correctly, the quality of every coat applied to parts after pre-treatment could be less than excellent, making for shorter lifetimes of coated parts. Since quality is of utmost importance at Burkard Industries, we take the pre-treatment process very seriously, which is why we created our proprietary 14-stage pre-treatment process.

While we will not outline the exact 14-stage pre-treatment process here, we can provide some details about the process and characteristics that show how stringent our pre-treatment process is.

Our pre-treat system includes spray and immersion stages to ensure that parts are properly prepared before they enter the electrocoat bath. We also offer an optional acid bath for laser cut and welded parts.

In the immersion acid cleaning step, also known as pickling, oxidation residue is removed from parts that are left behind by welding and brazing operations. This technique provides for a better-quality finished product since oxidation residue cannot be completely removed by alkaline cleaners. Pickling also allows us to process laser-cut parts which can cause issues for e-coating and powder coating. The acid cleaning stage can be bypassed for certain substrates, including aluminum or galvanized parts.

We have pumps and bag filtration at each stage in the pre-treatment process to ensure removal of all particulates from process solutions. This helps prevent contaminants from being deposited on parts.

Another method we employ to prevent particulates from settling on parts is by making the bottoms of our alkaline tanks and our zinc phosphate immersion tank cone-shaped. This results in collecting sludge, which is continuously pumped and filtered out in a closed-loop return system. The effect is that this minimizes the number of particulates in the tanks and, therefore, prevents the particulates from settling on parts.

When it comes to the pre-treat baths, we maintain tight control over the characteristics of the baths. We accomplish this by automatically injecting pre-treat chemicals into the system tanks with pumps controlled by the central PLC based on total square footage processed and monitored pre-treat parameters. Quality Control personnel also perform chemical titrations each shift to ensure process integrity.

In addition to controlling the quality of our chemicals, we control the quality of the water used in our pre-treatment process. Reverse osmosis water is used to supply and make up the last seven stages of our electrocoat systems to ensure that chemical tanks and rinse tanks are of the highest quality.

In the burp and tilt part of our pre-treatment process, the line is designed to tilt parts in tanks which eliminates problems associated with odd-shaped parts or parts with brackets. This process, also known as “burping,” is true to its name and eliminates air bubbles, which can leave a void in the coating. Burping also allows for better drainage to prevent drip issues commonly caused by parts that hold fluid in pockets. For parts that hold fluids in pockets, these parts can be tilted above the tanks to create better drainage in order to prevent drip issues.

To keep dust or other air contaminants from being introduced into the system, all pre-treat and e-coat tanks are inside an enclosure.

The rectifier allows the central PLC to control the voltage applied based on the square footage of the parts in the e-coat tank. This results in a consistent film build regardless of the size of the load processed.

Our cutting-edge system allows for six minutes of final rinse time after the application of the cathodic epoxy electrocoat. This process includes immersion and spray permeate rinses as well as a final immersion reverse-osmosis rinse, which minimizes the drip marks commonly associated with e-coating.

We have a two-zone oven, each with independent burners. This provides for a dehydration process to occur prior to the standard e-coat curing. Dehydration allows for rapid evaporation of pocketed liquids on complex parts, such as brackets, or on horizontal surfaces prior to entering the cure cycle. This minimizes the number of parts that are rejected because of drips, a problem that is commonly associated with electrocoating. The oven is equipped with filter banks which remove particulates from the air stream and provide for a smoother “Class A” finish.

Our four-spur power and free conveyor has fourteen load and unload stations. Part carriers remain stationary while loaded or unloaded at a station. The e-coat machine receives part recipe information with the use of an infrared smart-eye communication system.

Finally, we use the latest computer and controls technology for the monitoring and alarming of key process parameters. This includes system alarms, process temperatures, as well as pre-treat, e-coat bath, and operating-cost parameters.

Quality control employees receive system alarms on their cell phones, allowing for immediate reaction to correct issues that arise. We also provide historical tracking of key process parameters and recipe information from every load to meet ISO-9000 lot control requirements.

As you can see, Burkard Industries takes its responsibility for quality control seriously and applies this commitment to high-quality work starting at the very beginning of its overall coating process.