Turning Up the Heat on Paint Productivity
KME Fire Apparatus knows a lot about putting out fires, but the company, in fact, lit a fire under the productivity of the painting operation at its main fabrication facility with a new liquid system from Herr Industrial.The new line, commissioned in early 2010, churns out five times more finished parts per day in a footprint 55% smaller than the predecessor system.
KME Fire Apparatus knows a lot about putting out fires, but the company, in fact, lit a fire under the productivity of the painting operation at its main fabrication facility with a new liquid system from Herr Industrial, Inc.
The new line, commissioned in early 2010, churns out five times more finished parts per day in a footprint 55% smaller than the predecessor system. With a five-year ROI of 200%, the downsized system liberated 5,000 ft2 of space to expand the body welding department, yet has the capacity to finish more parts in three days than the old system could do in a minimum of five. The system, which still relies on hand painting, also boosted quality and consistency, according to the company, essentially eliminating rejects.
Part of the Kovatch Organization and headquartered in Nesquehoning, PA, KME Fire Apparatus is one of the leading builders of true custom fire apparatus for municipal, airport, military and industrial customers. Its diverse product line includes pumpers, tankers, rescue trucks, aerials and specialty vehicles. The company is a major supplier of fire equipment to thousands of departments including Los Angeles County and the City of Los Angeles. Kovatch also currently has the contract to build the R-11 refuelers used worldwide by the Air Force, including Air Force One at Andrews Air Force Base.
Approximately 600 vehicles leave the Nesquehoning complex each year, built from scratch or on any commercial chassis (e.g., the company is a dealer for Ford and International medium duty trucks).
KME's main fabrication facility is 188,000 ft2, and it's part of a campus of 14 plants that concentrate on chassis build, upholstery, electrical, testing, welding and other key operations needed to manufacture extreme-service, special-purpose vehicles to customer specifications. Considered a support plant, the fabrication facility has departments for painting, body welding and major component installation on the chassis. As a support operation, the plant supplies parts to all the other plants on the campus. Its paint department paints the bodies and other major parts of the vehicles, while cabs and other components are painted in other buildings.
PLAN, PLAN, PLAN
"Over the last three years, we've been strongly focused on improving our production capabilities and efficiencies," explains KME's Facilities Manager Bob Kuzma. "Our parts painting area was identified as a bottleneck in our production flow. Its inefficient layout also impacted productivity in our body welding department. We started planning an upgrade nearly three years ago, working with Herr and our suppliers of paint (PPG) and chemicals (Bulk)—every party associated with painting—aiming for a system that would improve employee safety, environmental compliance, productivity, quality and efficiency. We have to paint purchased parts, as well as those from our own operations, so we wanted a well thought out game plan before we committed."
The prior system consisted of a series of batch booths, using a labor-intensive system of racks to transport batches of parts, with painters racking and unracking the parts. "Our old line was outdated and broke down frequently," adds Building Supervisor Brian Mertz.
"Parts arrived in the department on a pallet, and had to be hung for washing. Our wash capability was limited in part size, had no dry-off section, and could only handle steel parts, while we need to paint aluminum, stainless steel and galvanized. Large parts had to be washed by hand. After washing, the parts had to be blown dry by hand before priming. After painting—in the same booth as priming—parts had to be unloaded from the line and placed on racks. The parts were then left to 'air dry' in ambient air, taking hours. The system used excessive floor space in the middle of the plant, affecting work flow in our welding and body preparation operations. We handled about 100 parts on an average good day, and it took eight or more hours to get a rush part through the finishing operation."
POWER-AND-FREE CONVEYOR LOOP SAVES SPACE
After inventorying all the parts that needed to be painted, studying production rates and other practices, and through several design iterations, Herr Industrial developed a space-efficient plan using a parts handling loop of power-and-free conveyor for stop-and-release transport. The design places most of the paint line on an underutilized area of shop floor elevated 42 inches above grade—"unfriendly" for the material handling needs of fabrication. This freed up 5,000 ft2 where body welding operations have since expanded.
The new system was installed over about eight weeks in late 2009, working through holiday shutdowns and around the production schedule of the plant. The line consists of approximately 200 ft of power-and-free conveyor running at a transport speed of 50 ft/min and a production rate of 12 carriers/hr. The conveyor passes through an indexing, stainless-steel, three-stage washer, convection dry-off oven, downdraft prime booth and flash section, downdraft top-coat booth with flash section, followed by a convection cure oven and exit. The line also includes a batch booth. The system is controlled by an A/B PLC with 10-inch color touch screen.
Parts loading and unloading take place in the same area. Carriers capable of holding a variable number of parts up to 750 lbs are released at a rate of about one every 5 min, resulting in an average cycle time of 45-55 min through the system. Parts more than 48 inches long or requiring special paint or processing are flagged at the loading station. The operator presses a ready-to-release button and the carrier enters the first stage of the washer when the next position is available.
The wash cycle time is selectable up to 180 sec. In the first stage of wash, manifolds of fixed nozzles reciprocate and spray the parts with an iron phosphate cleaner for about 3 min, followed by a 1-min drip, 2-min water rinse, then another drip cycle. The final stage applies a chromium-free sealer formulated for improved paint adhesion and corrosion resistance, followed by a drip cycle and dry-off oven. Up to two carriers can reside in dry-off for up to 10 min.
OFFLINE BOOTH FLEXIBILITY
The conveyor exits the dry-off oven and turns 90 degrees before passing a station where carriers can be stopped for unloading so that flagged parts can be moved to the batch booth. One of the keys to the system's efficiency and flexibility to handle rush parts is the batch booth. The primary system is sized to handle the most common part shapes and sizes. Large parts or those requiring special treatment are primed, painted and allowed to cure in the batch booth. "The offline capability of the batch booth adds great flexibility for us beyond painting the 5-10% of our parts we consider large," says Paint Shop Foreman Mark Vanak. "It allows us to handle anything out of the ordinary, but particularly quick repaints or rush parts needed to get a vehicle finished. Rush parts used to take 8 hours to get painted, dried and back to the production floor. Now, it's two hours or less."
Carriers not flagged for the batch booth continue and turn 90 degrees again into the prime booth for manual painting with up to 5 min residence time in the booth. The Downdraft paint booths allow the painters (one per booth) 360-degree access to the parts. Air pulled from the paint booths is filtered for solids and then exhausted to a stack. The booths use a raised-plenum design to eliminate the need for a pit in the floor.
With prime complete, the painter pushes a ready-to-release button and the carrier automatically releases and advances to first flash position, "de-dogging" to stop behind the carrier in the flash zone. Two carriers can reside in the primer flash zone for up to 5 min at ambient temperature. After time-out, the carriers automatically advance to the top-coat booth, if a position is available. After about 5 min residence time in the top-coat booth, the painter releases the carrier to advance into the flash zone, and finally to the cure oven, where four carriers can reside for 20 min at temperatures up to 250°. After cure, parts exit the oven, and turn 90 degrees to a stop/hold position until the unload/load position is vacant.
As part of the system upgrade, KME incorporated Graco ProMix proportional mixing systems and IWATA LPH 200 HVLP guns, Vanak added. The company sprays several hundred different colors, with heavy use of black for frames and green for military work—not just the colors traditionally associated with emergency vehicles. The paint system is PPG's Delta low-VOC catalytic polyurethane, targeted for a thickness of 3.5-4.5 mils.
BURNING WITH EFFICIENCY
The new paint line is so efficient, Vanak says, that it processes about five times as many parts per day as the old line. "We have significant capacity right now, and can easily support an increase in our company's requirements, which was one of our key goals," he adds. "We averaged about 100 parts per day on the old system, but recently did 600 in one day on the new line—still with just two painters. The new line handles all our production needs and has room to increase if needed. We hope to add work from other KME departments to fill the capacity, and we're also considering contract finishing to increase our utilization."