The Ekon-omy of Pretreatment

Article From: Products Finishing, ,

Posted on: 1/1/2004

Ekon Powder Coating-a quality-conscious powder coating production shop accustomed to excelling-finishes 18,000 different types of parts annually. Recently, in an effort to improve quality, the company made an investment in one of the mostcommonly overlooked, but very important, aspects of powder coating-its pretreatment operation...

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Precleaning in stage one

Precleaning in stage one uses a low-foaming, heavy-duty liquid alkaline cleaner.

ASTM B 117 Salt Spray Performance

Table 1: ASTM B 117 Salt Spray Performance Polyester Powder Coat

The ferroxphate process

The ferroxphate process produces powder coated products with excellent corrosion resistance. Salt spray tests run on steel panels pretreated in-plant show just 1.5 mm of scribe creepage at 500 hours.

Ekon's eight-stage washer

Ekon's eight-stage washer runs Chemetall Oakite's new five-stage "ferroxphate" process-clean, rinse, ferroxphate, rinse, non-chrome rinse. Three additional stages remove laser scale and light storage rust.

For Scott Landgraf, owner of Ekon Powder Coating (Buffalo, Minnesota), the decision to open a powder coating job shop ten years ago was a simple one.

“I’ve been painting just about my entire life,” says Mr. Landgraf. “Before starting Ekon, I painted lawn tractor trailers, wiped down with thinner and painted. It wasn't very good. I also painted cars and I owned a body shop at one point.”

When he established Ekon, Mr. Landgraf decided that the new company would perform powder coating exclusively. “I had heard a fair amount about [powder coating] and had seen it applied,” he said. “It seemed like a good up and coming business to get in to. My goal was to give my customers what I would want—a smooth, flawless paint, parts picked up and dropped off at my door, for a fair price. The finish had better last, and I need to be proud to give it to my customers.”

Today, Ekon finishes 18,000 different types of parts annually. The company’s million-unit annual production output includes end products as varied as components for industrial/commercial floor maintenance equipment, architectural construction products, point-of-purchase store fixtures, electrical enclosures, shopping carts and steel fencing.

Quality Pretreatment

Two years ago, Mr. Landgraf opened a new 28,000 sq ft facility, roughly twice the size of the original facility, giving Ekon approximately 44,000 sq ft, four on line powder booths (three of which are mini-cyclone powder booths supplied by Eurotech) and over 30 automatic and hand-held guns to apply a wide variety of advanced powder coatings including TGIC polyesters, epoxies, hybrids and super durables in four mini-cyclones.

As a progressive powder coater, Mr. Landgraf believes that every aspect of the finishing process is critical, but he singles out one particular phase of the operation—value-added pretreatment. “All powder coaters can do a good job making a part look good,” he says, “but it is truly what we are doing to the part before we paint that matters in the long run. It’s going to make that part look and last the way it should; it is going to give it some life.”

It was Mr. Landgraf’s desire to focus on quality that led to his recent decision to introduce a new conversion coating technology into the facility. (Ekon had previously used a high-performance iron phosphate process.)

In seeking ways to boost the quality of pretreatment, Mr. Landgraf turned to Chemetall Oakite, Berkeley Heights, NJ—a long-time supplier to Ekon—for assistance and was introduced to Gardobond® A 4920, a patent-pending conversion coating technology that bridges the salt spray performance gap between iron and zinc phosphates. Gardobond has been dubbed a “ferroxphate” conversion coating by Oakite because of the thin, amorphous, iron-rich pre-paint conversion coating that develops on steel substrates.

Gardobond® A 4920’s optimum operating temperature is 80-110°F, which is easily maintained through thermal transfer from the heated alkaline cleaner. Even when operating in this low temperature range, Mr. Landgraf was able to surpass iron phosphate salt spray results. Because this is considerably lower than the temperature required for iron phosphates, it has amounted to a considerable cost savings, giving Ekon a powerful incentive to conserve. The energy savings are projected to exceed the cost of the ferroxphate chemical.

The Gardobond A 4920 process is an acidic, liquid conversion coating applied immediately following the cleaning and rinsing stages of a spray pretreatment line. Surfaces must be cleaned prior to conversion coating, so Ekon uses a low-foaming, heavy-duty liquid alkaline cleaner in the cleaning stage. Because Ekon is quality-conscious, it uses RO rinses between every stage. The final stage at Ekon is a non-chrome seal that reacts with the Gardobond A 4920 surface to enhance paint bonding and under-coat corrosion resistance.

Concentrations of the ferroxphate solution are kept between two and four percent by volume. Instead of having to maintain tight pH ranges, the Gardobond process is easily controlled with standard titrations. Typical application times range between 20 and 90 seconds.

The Gardobondprocess is currently used in thelarger of Ekon’s two spray-washer pretreatment lines.Five stages of the washer handle the Gardobond process. The other three are used for removal of laser scale and light storage rust prior to ferroxphating, a step which Mr. Landgraf feels is critical to successful coating of laser-cut and welded parts.

The second line currently runs a conventional five-stage iron phosphate process. Mr. Landgraf indicated that this line may at some point be converted to the Gardobond process as well.

Shutting off the gas

Every morning, Ekon runs up the heaters of the Gardobond stage to 85°F then shuts off the gas. The heat-up takes as little as 30 minutes. For the rest of the shift they run with burners off.

On the eight-stage pretreatment line, Ekon is projected to save approximately $14,000 per year in heating costs, based on the reduction of operating temperatures by 32 degrees from the iron phosphate pretreatment used previously (also supplied by Chemetall Oakite). Additional savings may be realized by reducing heater maintenance, parts and labor.

Ekon has achieved this pretreatment economy and efficiency while actually enhancing salt spray results. The new ferroxphate coating outperformed the high-performance iron phosphate previously used.

As shown in Table 1 (at left), salt spray tests run on steel panels pretreated at Ekon and tested at Chemetall Oakite’s lab show just 1.5 mm of scribe creepage at 500 hours, compared to more than twice that—3.5 mm—for a premium iron phosphate coating. The paint applied after pretreatment by Ekon was a Sherwin-Williams TGIC polyester powder in both cases.

One of the unexpected benefits of the change was that washer clean-up and maintenance have been simplified. Descaling has not been necessary. Only a light haze appears on washer walls. Sludge is softer and lighter, making it easy to remove by washing down with a hose. In Ekon’s particularcase, disposal of spent solutions is nodifferent than that required for iron phosphates—adjust the pH and send the solution to the POTW.

Pretreatment for the long run

Though delighted with the results of the new ferroxphate line, Mr. Landgraf wasn't done tinkering. He added an acid stage to the Gardobond system (for removal of laser scale and light storage rust from laser-cut and welded parts prior to ferroxphating), calling it a “wonderful improvement on the product Ekon has to offer.”

In what has become a very competitive industry, Ekon Powder Coating has thrived by offering its customers long-lasting, high-quality powder coating finishes. At the same time, it has benefitted from the significant economies of ferroxphate energy conservation.

 

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