Like many manufactures, Mack Truck faced a problem with paint sludge as production volumes increased. Mack has implemented a new sludge-recovery system that has dramatically reduced cost and labor, water consumption, and chemical use.
Mack Truck paints its chassis with a high solid two-component coating in one of two spray booths. These spray booths were originally designed for painting approximately fifty chassis per day, but the increased demand for Mack Trucks has pushed the company's output to 76 chassis per day. This volume produced more solids and the system could capture.
Mack's plant maintenance manager says the company was draining and cleaning the pits every eight weeks. The system also required pump back flushing once a day due to sludge accumulation.
In the end, Mack opted for a new technology. This design provided a uniform cross sectional movement of paint laden water through the tank to avoid dropout to the bottom and confines the paint particles to be extracted within the consolidator. The consolidator absorbs the tank water at the rate of the circulation pumps.
Mack's 30 foot booth has two circulating pumps rated at 1,100 gallons per minutes each and the tank capacity is 7,000 gallons of water. The consolidators uniformly turn over the entire capacity of the tank in approximately 3.5 minutes. A total of 640 gallons of water is extracted at the end of both consolidators with a separate pump, driving 40 gallons through the centrifuge and returning 600 gallons back through the agitation headers in the tank. This process prevents the highly contaminated water from migrating and settling out in other areas. This short circuiting of the contaminated water to each of the consolidators builds up a higher concentration of paint particles to be extracted, thereby increasing the efficiency of recovery.
The consolidators deliver the water to a centrifuge, which alternates between the two sections of the booth. The cost effect use of only one centrifuge per booth is possible because the system delivers highly concentrated water to the feed stream of the centrifuge.
After more than seven months online, the newly designed system has eliminated all traces of sediment in the water pits. This has exceeded Mack's ambitious goals of reducing the pit cleaning task to once every six months. With the new system Mack expects to clean annually, if needed.
In addition to labor savings because of reduced cleanup, Mack has also saved money on chemicals. The centrifuge is so efficient, the need for extra chemicals to coagulate to paint was not necessary.
The new system has virtually eliminated clogging. The new process has additional filters and screens, so clogging is not a problem. An initial cost analysis at Mack has shown potential savings of nearly $100,000 per year. A typical system could generate cost savings in excess of one million dollars over the life of the system.
We have been in contact with the personal at the facility and they have informed us that production has been doubled and still are able to handle the paint loads with their recovery system.