THE PRODUCT LINE and the finishing line. Both have been refined at the Reading Body Works plant in Shillington, Pennsylvania.
Reading has been e-coating its service bodies since 1987. While the process was state of the art for the truck body industry 14 years ago, the company recently completed a third generation of its e-coat system, one that substantially improves output.
The major difference between the third version and its predecessors is the way that the new version continuously moves product through the finishing process. Previous Reading e-coat lines used square transfer — a process that involves moving the body over a tank, lowering it into the tank, lifting it out and suspending the body over the tank to allow excess coating to drop back into the tank, and then moving on to the next tank in the series. Movement is either a true horizontal or vertical.
So what's the big deal about the new system? The new line offers triple the output because the line moves continuously through the process. Instead of hovering over a tank before being lowered into it, bodies are gradually submerged as they move along a conveyor line that slants down over each tank.
In addition to offering greater capacity, the new e-coat line offers an overall finish that is as good or better than the slower system. That's because the geometry of the conveyor path on the new line helps fight trapped air pockets deep inside service body compartments — bubbles that otherwise would keep the coating away from the steel. Bodies enter and leave the tanks at opposing 30° angles. This results in a total difference of 60° from the horizontal plane — enough rocking to allow the e-coat to contact the deepest recesses of the service body interiors.
Reading is still pleased with the performance of its second-generation e-coat line. The company is using it to e-coat lower-volume products. However, the new line offers the manufacturer with production flexibility as well as improved capacity. That's because sections of the line can be stopped or diverted without affecting the flow of the rest of the line.
“Continuous electro coating, compared with square transfer, is more simple and consistent,” explains Dan Perlman, vice-president of manufacturing. “Square transfer requires a lot of computer controls. With the new line, bodies move in and out of the tanks at 30° angles. By moving in and out of the tanks at opposite angles, it is less likely that the bodies will trap air.”
The big advantage of square transfer, Perlman says, is its efficient use of floor space. Sloping conveyor lines require more room, and Reading built a 60,000-sq-ft addition to its plant in order to accommodate it.
“We have dedicated a lot of our building to our finishing process,” Perlman says. “The new line has helped relieve a bottleneck for us — post-paint operations.”
The new line also streamlines the process of cleaning out the tanks. Reading now can lift the entire circulation system out of each tank if necessary to remove settlement, a capability that Perlman says Reading developed in-house.
Although the new e-coat line is not as compact as the previous ones, Reading reduced the amount of floorspace the new line needs by using overhead space extensively.
The most prominent example is the bake oven, built entirely overhead. After bodies have been immersed in the series of tanks, the conveyor line lifts them from ground level to the elevated oven. Bodies come into the oven through an opening at one end of the oven and exit through the opposite end.
Creating such a mezzanine would not be possible without substantially beefing up standard sheet metal building specs. Walls and roof have been reinforced, with wide-flange I-beams used as roof supports.
“You won't find any lightweight trusses,” Perlman says. “But this structure enables us to have the mezzanine and still have an unobstructed first floor.”
Also overhead is the monorail conveyor system that moves product through the system. The monorail, the same type as that used in automotive plants, can be stopped at specific areas without requiring the entire line to be shut down.
Filling the Tanks
Because the conveyor line gradually lowers the bodies into the various tanks, the new Reading e-coat line requires larger tanks — and more liquids — than the square transfer line.
The new system has seven tanks measuring 80' × 18' × 8'. Scattered between these tanks are five spray rinse stages. The tanks include:
Cleaner. This removes oil and grease from the bodies, promoting stronger adhesion of the coating.
Phosphate conversion coating bath.
Permeate. In this tank, surplus e-coat is removed and returned to the e-coat tank.
Following the final rinse, bodies move into the oven for the finish to be cured.
“We use an acrylic electrocoat,” Perlman says. “Our option was to use an epoxy primer, but it tends to chalk and cause poor adhesion with the top coat if sunlight penetrates the base coat and clear coat. Since we are putting on a primer on bodies that may sit in the distributor's yard, we thought an acrylic e-coat was a better choice.”
Keeping in Compliance
One of the advantages of an e-coat system is its ability to meet environmental regulations.
“The system we built in 1987 would still comply with all regulations we have to meet,” Perlman says.
Other advantages include:
Coverage. Submerging a body in paint offers excellent coverage — particularly when the coating is electrostatically charged.
Corrosion protection as a result of consistent coverage of a well-bonded coating.
Application efficiency. While conventional spray techniques waste about half of the material being sprayed, an e-coat system deposits about 98% of the coating onto the product.
No solvent pull-back on sharp edges. This results in more consistent coating thickness.
Repeatability. Controls are in place to keep variables such as temperature and voltage constant. Plant personnel record those variables daily.
Supplier support. When a manufacturer has to keep 80,000-gallon tanks full, his coating supplier generally views him as a good customer.
Reading has made changes to its product line, too — introducing the Classic II service body.
“We looked at what makes our body useful,” says Dick Gordon, co-president. “For example, a four-inch kick-up on the back compartment has been something that has distinguished a Reading body. This improves the angle of departure and keeps the truck from looking overloaded.
“But we have dropped that feature in the Classis II. This produces more room in the rear compartment.”
Doors now use a heavier gauge steel (18 gauge instead of 20) for the outer skin. A full-length hat section reinforcement provides additional strength. A-60 galvaneel steel is still standard, providing 6/10 ounce of zinc coating per square foot.
Reading engineers also redesigned the compartment doors for a longer-lasting, watertight seal. They also decided to mount the gaskets on the doors and away from the compartment loading areas, and added a new baffle in the doors to provide additional sealing. The automotive-style seal is patent pending.
Also new are the use of free-wheel locks. Like those used on automobile doors, these locks disconnect the door handle when locked — making them more resistant to prying.
A slam-action tailgate is now standard, much like those found on pickup trucks.
Locks, seals, doors. Like the system that coats them, the new Reading Classic II service body reflects accepted practices of today's automotive manufacturing industry.