Vacuums become the big guns in war on coolant contamination
Take 54 machine tools, multiple shift operations, precision aerospace and industrial components, and materials ranging from cast iron to bronze, brass, titanium and all the grades of stainless steels. Then take thousands of gallons of coolant flushing through those machine tools. Add a mysterious bacteria that's causing skin rashes, plus an unusually high rate of coolant contamination. Now, you're looking at a serious maintenance problem in need of a fast and permanent solution.
This was the situation faced by Steve Kiefer, manager of maintenance and OSHA compliance at Rexnord Corp's Seal Operation, Wheeling, IL. His plant makes mechanical seals for a wide variety of aerospace and industrial applications.
Maintaining Rexnord's quality reputation is a key role played by Mr. Kiefer and his department. The coolant is checked regularly by refractometer and changed as often as necessary to maintain purity and proper strength level; too strong can pose health problems, too weak can result in faster machine wear and shortened tool life. Contamination, at any level, is just plain unacceptable.
Mr. Kiefer traced the source of contamination and bacteria growth to chips and fines that found their way into out-of-sight or inaccessible nooks and crannies of the dozens of CNC lathes and machining centers.
"We found that chips and fines were working their way behind machine guarding and cover plates," says Mr. Kiefer. "Behind some of the cover plates inside the working areas, we'd find blocks of compacted fines. Over time, they had become, literally, 20 lb bricks so hard you'd need a saw to cut them apart." These blocks of chips and fines turned out to be ideal homes for bacteria growth.
In other areas, behind guarding doors and up in corners, larger chips would escape normal cleaning out procedures. Coolant clinging to these chips were additional "breeding farms" for bacteria.
The source of the rapid contamination of the coolant also turned out to be the fines – speck-sized chips clinging to machining areas and chip troughs, escaping flushing and blown-down cleaning and collecting underneath the filter screens. Because of the wide variety of metals being machined, the resulting compositions in the coolant tanks were creating a chemical reaction that quickly shortened the life of the coolant. "This chemical reaction," according to Mr. Kiefer, "was actually eating the bottoms out of the chip troughs. We were sending them out to have the bottom plates welded at about $300 each. Plus, we had to contend with the mess of the leaks, downtime for maintenance and repair, and overall operator discontent."
A workable idea
Since the cause of the vast majority of these problems boiled down to the clinging, escaping, and generally pain-in-the-neck chips and fines, using vacuums in a machine maintenance program seemed the perfect answer.
Mr. Kiefer ordered a dozen shop vacuums and worked out a schedule for the operators to vacuum inside the work areas of their machines, especially those places where they had found the concentrations of chips and fines.
"The idea was good," says Mr. Kiefer, "but the shop vacuums weren't." The filters and motors inside the shop vacuum kept clogging, interior plastic baffle plates shattered from the striking force of the larger chips, the plastic pick-up tools frequently broke, and the ribbed hoses often caused "bridges" of chips to form, stopping the vacuum action.
"We realized we had to have quality to get quality," says Mr. Kiefer. "In this case, it meant talking to Goodway Technologies Corp in Stamford, CT. We had researched the market, and it seemed their VAC-2 wet/dry industrial vacuum fit our requirements. In this case, we're talking about two powerful motors protected from chip and coolant damage, steel baffling, a nonclogging filter system, a smooth hose interior to prevent bridging, a rugged stainless steel tank and high static water lift. Goodway worked with us and even made especially long pick-up tools so our operators could easily reach everywhere inside their machine tool cabins without effort."
Mr. Kiefer ordered five VAC-2 wet/dry industrial vacuums for the plant floor and a sixth has been put to use in the coolant recovery room. Calling the operators together, he tacked up a layout of all the machining cells and let the operators decide the most convenient location for the vacuums.
"The operators all vacuum their machines' interiors two or three times a week now," says Mr. Kiefer, "and especially when changing over from one part material to another." The bacterial problem has disappeared, coolant stays viable much longer, and there is far less wear on the machines and tooling. Each week, the maintenance crew uses a sump-sucker to siphon the coolant out of a scheduled number of machine tools into 55 gallon drums. Recycled coolant is returned to the machines and the drums are brought into the recycling room. Here, aerators are placed in the drums and the dirty coolant "decants" for two days. Using the sixth Goodway VAC-2 wet/dry industrial vacuum, just barely touching the surface, all decanted hydraulic and way oils are removed. What would take over an hour to do with the typical disk skimmer is accomplished in less than 10 minutes with the VAC-2. After skimming, the coolant is heated, pasteurized for 16 hours, cooled, filtered, checked with a refractometer, reconcentrated, and returned to the machine tools. Waste oil is shipped out by certified waste contractor.
"On the bottom line," he says, "the VAC-2s are helping us save in coolant costs, reduce contamination, and eliminate bacteria rashes."
A Goodway VAC-2 quickly skims off decanted hydraulic and way oils in Rexnord's coolant recycling room.
At Rexnord, all machine tool interiors are vacuumed at least two or three times a week as well as after part changeovers involving different workpiece materials.