January 2008 Edition

COOLANT

Green Chemistry Cures the Bacteria Blues

Environmentally friendly coolant eliminates bacteria, improves system life

Hydraulic lifts were the bread-and-butter of Eaton Corp., Saginaw, MI, but to mix a metaphor, there was a fly in the ointment. Well, more like bacteria . . . bacteria in its coolant, and it was costing money.

The bacterial buildup in the 174,347 ft² facility's coolant systems required frequent expenditures for bio kits and ongoing system dumps to control the problem.

Through a partnership with third-party fluid management consultant, Houghton Int., Valley Forge, PA, Eaton explored coolant options to eliminate bacteria, reduce costs, improve product quality, and extend tool and system life. Together the two companies selected an environmentally friendly, vegetable-based coolant that would have a positive impact on the inner-city plant's relationship with the city of Saginaw.

Pre-green Era

Eaton's three central coolant systems, containing a total of 100,000 gal of coolant, feed five metal-working machines that perform processes such as broaching, mill cutting, and grinding. All used a mineral oil-based coolant. With demanding machining applications, the plant's coolant issues ranged from operator complaints about odor and dermatitis, to foaming, swarf build-up, and reduced tool life.

To keep bacteria at bay, Eaton used bio kits composed of chemicals that eventually made their way into Saginaw's wastewater system. Eaton had to shut down certain machines once a month for cleaning and to powerwash the trenches to remove fungus. System dumps of the former coolant reached up to 70,000 gal to 80,000 gal in 18 months for a single sump. Also, Eaton had to replace bearings every two years due to wear from ineffective coolant.

Eaton contracted with Houghton Fluidcare. Fluid management specialists surveyed all the lines, products, and processes, and recommended ways to reduce costs and waste, improve output, and solve the operator complaints. Houghton recommended a trial of its coolant technology with the goal of finding one environmentally-acceptable coolant that worked in all the systems and would last longer without souring.

Houghton's site manager, located at the Saginaw plant, sought methods to consolidate suppliers and products. The manager's priority was to find a single coolant that improved all of the different machining processes.

After a thorough product search, the consultant recommended a vegetable-based coolant that contains technology field-proven to last longer in the machine sump than traditional coolant.

Bye-bye Bacteria

After successful trials, Eaton began to switch over coolant systems to the new vegetable-based coolant. The consultant tested for pH, and completed a titration and an acid split to test for coolant concentration daily. Each week, they tested for bacteria using bio-dipslides.

By changing to the vegetable-based coolant, Eaton increased grinding throughput by $1.7 million per year. Without scum buildup on tools, it achieved more parts per piece of tooling. Tool life is consistent, and less regrinding improved air quality within the plant. There is also less wear and tear on bearings.

Eaton has achieved a consistent fine level of 300 ppm without manually bypassing the system, as was required with the previous coolant. Easy removal of fines and heavies led to better grinding quality. Also, operators no longer complain about odors.

When using bio kits with the previous coolant for bacteria control, plant personnel had to dump one-third of the system coolant each time. With the new coolant, one system used the same vegetable-based coolant for three years without dumping.

Eaton's coolant usages are now low enough that they can haul 100 percent of the plant waste offsite. With the old coolant, Eaton treated waste internally before shipping it to the city for further treatment. After integrating the green coolant, plant waste production diminished so much by September 2006 that Eaton no longer has to rely on the city for disposal.

Clear Skies Ahead

Eaton's success with switching to a green coolant led the facility to look into congruent, vegetable-based hydraulic fluids. Plant managers said they hope chemical compatibility will reduce consumption at all levels. The fluid consultant recommended such a course because, with this configuration, Eaton would not need to strip oil from the coolant system, thus avoiding the resulting coolant loss.

Eaton's switch to vegetable-based coolants was such an environmental success it intends to share its model with other Eaton plants. Houghton Int.

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