Saving water, saving dollars

In the face of rapidly depleted fresh water supplies, the industrial sector is learning that reducing water usage and increasing reuse is an essential ingredient of productivity and profitability. This is increasingly true in the United States, where 46 percent of all water consumed is used by industry, says Dr. Peter Glieck, President of the Pacific Institute for studies in environment.

Manufacturers and fabricators are major stakeholders in this global water conservation effort. Ford Motor Company focuses on process water reuse not only to conserve water, but also to improve process uptime and product quality and reduce disposal and maintenance costs. To do this, they are incorporating advanced separation technology and addressing pollution like oil, grease or dirt to extend the life of fluids like cleaning solutions and coolants.

New realities in aqueous separation
Automotive manufacturers and metal fabricators, for example, are using a new and highly efficient technology — dynamic oil separation — to continuously remove process oils and even minute contaminants from an aqueous cleaning solution while it is being used.

Traditional mechanical separation methods are based on one of two principles: (1)gravity separation, in combination with weir skimmers and tank overflow, or (2) adhesion, with hoses, wheel/disks or belt skimmers used to adhere oil to lift it from the surface of bath water. Both methods are problematic, particularly in high-volume production settings where changing or maintaining aqueous baths involves downtime.

Adhesion separation often allows dirt to settle through surface oil and cycle back into the bath water, leading to dirty parts. This also requires frequent solution changes. The adhesion method also draws up and removes cleaning agents along with water and oils, creating “wet” oil and adding to oil disposal costs.

The overflow (decanting) method wastes vast amounts of coolant or cleaner from the bath. Another method, which uses honeycomb-like traps or plates called “coalescing media” to separate and capture oil and contaminants, has proved to be inefficient and maintenance-intensive due to its sensitivity to dirt.

Dynamic separation technology operates on a different principle — Bernoulli’s Effect — where increased stream velocity in a fluid results in internal pressure reduction. The Bernoulli Effect is probably best known as the principle that creates the “lift” of aircraft wings. Dynamic separation uses fluid pressure differential to enable the separation of liquids of differing specific gravities. This technology was developed by Aqueous Recovery Resources (ARR) and incorporated in its Suparator systems specifically for this type of application.

This technology removes oil so effectively that dirt and other foreign matter are also separated with the oil. Eliminating these contaminants creates a much cleaner process and cleaner, better quality products with fewer rejects.

Dynamic separation also extends bath life, providing significant savings in detergents. Bath changes are greatly reduced, water is conserved, oils are more efficiently recycled and far smaller volumes of cleaners and coolants need disposal.

Ford Dearborn — pressing for perfection
At Ford’s Dearborn plant a 2,600-ton Schuler press using up to 300 tons of dies turns 700,000 pounds of steel per day into doors for best-selling Ford F150 pickup trucks. At the press area, stacks of steel “blanks” arrive, each coated with a thin film of mill oil to deter corrosion. The steel blanks must be washed to remove that oil, dirt and other foreign matter before they can be stamped.

“Oiled blanks attract dirt like a magnet, so they have to be washed thoroughly,” says Ed Spencer, controls engineer at Ford Motor Company’s Dearborn stamping operation. “We don’t want that oil, which may have dirt in it, to get into the die. So, we spray-wash it with a detergent solution pumped up from a huge tank downstairs.”

If even one piece of dirt “birdshot” remains on a blank when the giant press hits it, the finished piece will have a dimple that ruins the door. At the rate the Dearborn plant stamps doors — 700 pieces an hour — if a dirt problem is not identified quickly, the result could be a lot of scrapped metal in a very short time.

“We have very tight demand,” Spencer explains. “We have an assembly department downstairs that puts the inner and outer door panels together and then we ship it off to assembly. If we are shut down because of dirt issues with the cleaning solution, we have problems: productivity loss, manpower standing around and wasted parts.”

Realizing it needed an efficient and reliable separation technology to maintain clean processes, the Ford stamping operation installed a Suparator unit in 2006. In addition to meeting Ford’s high quality standards, Spencer wanted an oil separation technology that would help maximize the uptime of the critical Schuler press and its high volume requirements.

Now, after the dirt and oil are washed off the blanks, the cleaner returns to the holding tank where the Suparator removes fluid from the surface. Any oil in this concentrated stream — and any entrained dirt — is separated from the fluid continuously and without water or detergent.

“In the past we used a centrifuge system and tried to get the heavy particulate out of the solution that way, but that was a maintenance nightmare,” Spencer says. “We tried to remove the oil with a hose-type skimmer, a plastic tube that went around in a circle, and the oil would cling to it, supposedly. But it never really worked.

“The Suparator technology works about 100 times better than the other system. And the key is it takes out the fine dirt particles better than the centrifuge ever did.”

The Suparator has also extended cleaner life from its prior two weeks to at least two months. That pays off in added productivity, especially considering that there is no backup equipment for the giant Schuler press.

“We’re realizing our major savings on quality and availability,” he says. Uptime is now averaging up to 95 percent, which is excellent for the stamping industry. We also have less wasted materials and get extended cleaner life. Obviously, that adds up to a lot.” Item 152

This article appeared in the February/March 2008 issue of MRO Today magazine. Copyright 2008.

Back to top

Back to Case studies/Ideas that make sense archives