Reducing Paint Use While Increasing Production

Trailboss Trailers, Inc., Macon, MS, manufactures tag-a-long and heavy-equipment lowboy trailers with capacities ranging from 6 to 60 tons. Since 1990, the company has gradually expanded its product line, increasing sales 25% a year.

Like many other fast growing finishing companies, Trailboss faced a number of environmental compliance issues, including VOCs that were emitted by the company's paint line. The company's previous paint line was a conventional air-assisted airless system that pumped a single-component protective coating from 5-gal pails to spray guns inside the spray booths. Each trailer required approximately 15 gal of primer and paint to achieve the protective finish required by Trailboss.

In an effort to reduce VOC emissions and lower the cost of running the paint line, Trailboss has worked hard to keep informed of new finishing practices and equipment that can make it more efficient. The desire to stay on the cutting edge of finishing technology led Trailboss to make a number of changes to its finishing system.

The first change made to the system was to install PRO AA4500™ air-assisted airless electrostatic spray guns from Graco Inc.-Industrial Products Division. The combination of high-voltage (up to 85 kV) performance and high-pressure air-assisted airless atomization (air pressure up to 100 psi and fluid pressure up to 3,000 psig) allowed the spray guns to provide excellent wrap, increasing transfer efficiency. "Without a doubt, the new electrostatic spray guns have improved our efficiency and finish quality," said Lee Smith, paint shop supervisor. "They significantly reduced the time we allocated to paint the trailers and cut the amount of paint we use on each trailer in half."

Before Trailboss changed spray guns, it used a single-component paint to coat its trailers. But, because the new spray guns have the ability to spray at high fluid pressures, providing the additional power needed to atomize high-solids materials, Trailboss was able to switch to a two-component paint. The two-component paint and catalyst, KEM 400, was supplied by The Sherwin-Williams Company. The increased solids in the two-component paint further increased transfer efficiency. Since less paint was used to coat the trailers, Trailboss estimates it has decreased VOC emissions by 10%. The two-component paint also reduced the curing time, which helped lower the operating costs of the paint line.

The change to a two-component paint led Trailboss to make one other change. Two-component paints must be mixed before they are applied. There are two ways to do this: batch or on-demand. With the batch process, the painter estimates the amount of paint needed to coat the part. That amount of paint is then mixed and applied. However, if too much paint is mixed, the leftover paint cannot be saved because it will harden. Also, if not enough paint is mixed, the painter may have to waste several gallons of paint for a new batch, since the paint usually comes in 5-gal pails.

The other way to mix two-component paints is with an on-demand process. Trailboss uses the Variable Ratio Hydra-Cat^® (VRHC) pump and proportioner from Graco to do this. The proportioner meters, mixes and pumps the two-component paint from 55-gal drums in a pump room to the electrostatic spray guns in the adjoining booth. With the propor-tioner, Trailboss is able to virtually eliminate the waste, mess and inaccuracy often associated with batch mixing. Also, by supplying the mixed paint on demand, Trailboss has reduced the concerns about pot life and the related changes in paint viscosity, thus providing a more consistent finish.

The proportioning system also features back-geared agitators mounted on lifts. The agitators gently shake the material, keeping the solids from settling to the bottom of the drums. A 0.75-inch Husky™ diaphragm pump transfers the base and catalyst from the 55-gal drums to the proportioner. The proportioner meters the components to an 8:1 ratio, then mixes the material through a mixer manifold and transfers it to the spray guns. "We have three dedicated guns for the primer and three guns for the topcoat, which run off the proportioner," stated Mr. Smith. "We strive for a 2- to 3-mil primer coat and a 4- to 6-mil topcoat."

The proportioner's variable ratio capability allows Trailboss to change the mix ratio without having to purchase a new proportioner. The company can change the ratio quickly if a customer requires a specific coating or a new paint with a different mix ratio. "The system is very flexible. It allows us to give the customer exactly what it wants," explained Mr. Smith.

The new spray guns, two-component paint and variable ratio proportioner have allowed Trailboss to keep its cutting edge image, reduce its VOC emissions and lower its operating costs. "The industry is very competitive," said Mike Banks, owner and president of Trailboss. "When someone in our industry changes one of its manufacturing processes, and the change improves its product's quality or reduces its cost, everyone has to make the same changes to remain competitive. We're not always the leaders when it comes to change, but we try to keep pace. Right now, the finish we put on our trailers says good things about us."

To learn more visit Graco Inc.-Industrial Products Division and The Sherwin-Williams Company.