A fan is a precisely engineered piece of equipment that provides control of air volume and direction in order to control a process.Every major component used in a powder coating system depends on the movement and control of airflow to operate as intended. A washer bay has to have exhaust to direct the vapors to atmosphere. A powder booth has a collection system to capture over sprayed powder. Containment of vapors and overspray is critical to a safe, clean environment. A cure oven must have exhaust to remove byproducts of the cure process and prevent them from fouling the process or the building. These airflow controls depend on industrial fans.
When Robert Hartzell followed his father into the lumber business in 1917 he had an engineering degree and a strong interest in aviation. As luck would have it, Hartzell Hardwoods was approached by Orville and Wilbur Wright and Glen Curtis to select straight grained walnut lumber to make aircraft propellers. The company went on to make propellers for both World
Wars and started the Hartzell Walnut Propeller Company in Piqua, Ohio. In 1927, they engineered an airfoil fan to improve air quality in their own plant and went on to market the new fan design to other plants. The airfoil fan was quieter and more efficient than other options and the company quickly grew.
Through the years, Hartzell has developed many innovative fan designs made of diverse materials, including metal, fiberglass and other materials. These materials need a coating that will protect the fan from breakdown when exposed to the various elements moved through the airstream where the fan is installed. Liquid coatings were the only options available to them when they got into the industrial fan market in the early part of the twentieth century. They had to have a lot of building exhaust, they generated a lot of waste, and they took a long time to air-dry but the fan was protected from corrosive influences. The liquid coatings could be applied in multiple coats to achieve certain levels of performance. It took a long time between coats but it was the only option for reliable high performance.
The long dry times, high level of material handling, different coating formulas and high cost of the coatings was a challenge. Regulations regarding solvent handling and disposal were also an issue. There was a clear incentive to consider other coating options.
Switching to Powder Was a Breeze In 2012, Hartzell began to consider powder coating as an alternative to the liquid paint they had used for their products. The powder coating operation would be a new process to Hartzell and they worked diligently to educate themselves and their customers on the value and benefits they could achieve through conversion. After completing their research, they determined that powder coating their research, they determined that powder coating could achieve the durable, long-lasting finish they needed while reducing the process time and handling. It would also also them to consolidate several discreet paint operations into one small operation.
In 2013 they launched a powder coating system to improve the protective value of the coating on their valuable fan product line. An existing building needed to be modified
and cleared to provide the space for the system. They were able to install the powder coating system in four months. It reduced the floor space they had been using for paint by 50
percent and allowed them to bring several operations into the one plant so they did not have to transport from one plant to another. And their customers are thrilled with end finish they are now providing.
Mike Harwood, manufacturing engineering manager at Hartzell, was the primary project leader. “This was a very successful project for us,” says Harwood. “Even though we are an OEM, we are basically a job shop. We need to be able to handle a large variety of parts every day. With this system, it does not matter what size or shape we have to coat, if it goes through the door we can handle it.”
The product variety is unusual and that drove the company to look at a unique system that would be flexible for volume and size and make it easy to handle very large and heavy parts. Chris Wright of Sustainable Technology Solutions introduced them to a rail system in use by several job shop powder coaters with similar challenging part variety. Wright owns and operates Carolinas Custom Clad (CCC),
a job shop coating facility in Rock Hill, S.C. The batch-type powder coating line they designed is based on a similar rail system used at CCC and offers a unique rail system that helps them move product around to the various steps in the process.
The largest part that the system is capable of handling is 10' x 10' x 20' long. They do not run anything that large at present, but they do run some parts that are as tall as 9' x 5' wide x 4' long.
The new powder coating process also improves production efficiency because it provides a controlled cure process. The old liquid coatings they used were air-dry products that could take a very long time to dry enough for handling and shipment. In addition to the faster dry times, powder coating does not involve additional pre-mixing, solvent additions, or viscosity adjustments, which means less product variation and better control over quality.
Sean Steimle, president of Hartzell Air Movement, explains, “This curing and cross-linking process bonds the powder coating to the surface of the substrate and creates a very durable and long-lasting finish. Our fans are installed in very corrosive environments and we are constantly looking into ways to increase the lifespan of
our fans for our customers.”
The system includes a media blast booth for removal of inorganic contamination such as rust and weld smut. Not all of the products require blasting but some surfaces have significant amounts of oxidation that must be removed for good bonding and corrosion resistance.
Hartzell also installed a wash bay with a hand-held wand cleaning and treatment system supplied by Pretreatment Equipment Manufacturers (PEM). The wand system features fixed orifice injectors to introduce the chemistry to the system with precise concentration control. The cleaning system provides a method to treat aluminum and parts that do not need blasting and to add a chemical step for better coating adhesion on all substrate materials. It can supply an alkaline cleaner for thorough removal in organic soils, an iron phosphate solution to provide a conversion coating and a fresh water rinse to removal all residual, un-reacted chemistry prior to coating.
There are two ovens used in the process: one is for drying and the second one for cure. The ovens were provided by Rapid Engineering Inc. in Comstock Park, Mich. The dry-off oven features a side-wall discharge duct system that blows heated air directly
onto the parts. The direct impingement provides thorough drying in less time and with less energy than other duct systems that discharge from the top or bottom of the oven. The cure oven has top-mounted ductwork that provides uniform heating and does
not disturb the uncured powder. Both ovens feature gas burners with 40:1 turn-down ratio to provide exactly the right amount of energy for the different masses of part.
From the equipment side, the most critical part of the system is the material handling rail system. The system uses a multi-rail design for ease of loading/unloading, a powered bridge crane to move the loaded parts to various system components and a rail system to move parts into and out of the various work stations. The parts
are suspended from hand-push trolleys that ride on the rail system, making it easy to pull the work into and out of the process stations along the overhead rail. The rail system makes it possible to lift parts in the load station with a crane and hang them on hooks suspended from the rail. The rail can be easily moved over to the bridge crane and moved to any of the work stations along the line of the system. Once the load rail is aligned with the rail in the booth the parts are pulled into the booth manually.
Hartzell chose Parker Ionics for the manual application equipment. The Parker GX 8500 Series unit offers a method to control the current. Their Pulse Power technology helps control the current and voltage when the gun is moved to different target distances during application. The gun is equipped with feed hoppers to provide uniform fluidization for consistent delivery of powder.
Hartzell makes fans that go intosugar beet fields, exhaust systems, waste treatment systems, nuclear reactors, marine applications, gas and oil, food processing and hundreds of air movement applications. They all need the protection of a high quality coating but not all are the same. They break the finish into several different categories based on the end use of the fan. These include their standard one-coat product line and higher performance coatings that need more protection from the elements. General duty fans are typically single coated while fans used in a marine environment or other challenging applications receive a powder primer coat and a TGIC (triglyciyl isocyanurate) topcoat. The TGIC powder provides protection against weathering and resistance to moisture and chemicals. Standard colors include blue, green and safety yellow but they also will apply colors that are required by their customers.
Some products need exceptional corrosion resistance. These products receive the two-coat process and some special part preparation to elevate the performance for more extreme conditions. The part is media blasted to remove all inorganic materials (rust, weld stains, etc.) and then washed to make sure there is no residual oil or dirt on the surface. A single coat of zinc-rich primer is applied and partially cured. The topcoat is applied and the part is fully cured. The resulting finish is capable of achieving several thousand hours of salt spray resistance and holding up to extreme environmental conditions.
Hartzell chose TCI Powder Coatings, Ellaville, Ga., as their powder supplier. TCI worked with them early in the project to help determine whattypes of coatings would be needed for the various product lines. They also worked to develop their standard blue and green colors and provide products that were flexible for different end-use requirements and helped them prepare specifications. They have worked with them since the beginning to develop powder alternatives to almost all of the traditional liquid coatings used in the past. They continue to work with Hartzell on specialties and high temperature coatings.
Now that Hartzell has had time to run the powder system for a year, they have learned to run the process effectively and currently enjoy a near-zero defect operation with a substantial improvement in quality and almost no rework. The system is working so well that they are continually looking at products that are currently specified for liquid coating and working on options to convert them to powder coating. This includes OEM and special colors, multi-coats designed for extremely high performance, and high-temperature applications. They have moved a very high percentage of these products to the powder process and continue the effort to convert as many as possible. Some of their customers are very receptive to a newer “green” technology to help them reduce their own carbon footprint.
Overall, the decision to install a powder coating line has proven to improve Hartzell’s process and quality while reducing cost. The company is planning an expansion to allow them to run more products and gain flexibility for loading and unloading at both ends of the system.
Rodger Talbert, director of business development at Colmet,
was executive director of The Powder Coating Institute in
2011-2012 and a veteran in the powder coating industry. He
can be reached via email at firstname.lastname@example.org .