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Technology for Energy Conservation

 

Innovations generate efficiency and cut operating costs



By James Koelsch
Senior Editor

         

Atmosphere will be important in Hall D in the East Building, the location of the Machine Components/Cleaning/Environmental pavilion. And the atmosphere there will be one of total environmental, purifying, monitoring, and safety excellence, according to the show's sponsor. Others, however, describe it a tad more basely, reducing it to a mere catch-all for the 200 or so exhibitors that don't fit anywhere else.

Although both descriptions ring true, another, more relevant theme will pervade the atmosphere this year, and unite the disparate technologies being shown. It's oil and energy conservation. As prices for oil and other sources of energy continue to soar, most manufacturers are looking for ways to control these costs. This pavilion just might have the show's highest concentration of exhibitors that have technology available to soften the blow of higher oil and energy prices.

If you want an example of how various kinds of machine components can contribute to energy conservation, look in the booth that will be occupied by Baldor Electric Co. (Fort Smith, AR). This exhibitor will be introducing new AC permanent-magnet motors that are much more efficient than conventional designs.

Because the electric motor is a mature technology, these designs represent an evolutionary, rather than revolutionary, advancement. Their newfound efficiency comes from creative shapes and positions of the magnets within the rotor. "Using new magnet materials available in the market, we have developed AC motors with significantly greater power densities and higher efficiencies," says the company's Randy Breaux. In some cases, efficiencies are two to three NEMA bandwidths greater than older, high-efficiency designs.

This allows manufacturers to make motors in lighter, more compact units, a fact that could create a temporary challenge for their proliferation in replacement applications. "They may be one or two NEMA frame sizes smaller," explains Breaux. "So, they are not necessarily drop-in replacements for existing NEMA-frame-size motors." Because these units will not fit the frames of machines already in the field, original equipment manufacturers will most likely be their initial customers.

Because they come with slightly higher price tags, cost will be another hurdle for these motors to jump. "When you consider, though, that they consume less energy than conventional motors, the payback will offset the additional cost quickly, typically within two years," notes Breaux.

There is another factor to consider in any cost analysis. Because these motors require variable-speed drives, an application not needing a drive may not be cost effective.

The calculus for selecting cutting fluids is also changing, because of the high and unstable cost of oil. Not only is the rising cost of oil boosting the cost of petroleum-based cutting fluids, but its fluctuating prices are also making it difficult for some shops to budget for them. Consequently, the cost advantage that petroleum-based fluids have enjoyed over their petroleum-free competitors is diminishing.

Because the trend shows no signs of abating, many producers are looking into alternatives. Hangsterfer's Laboratories Inc. (Mantua, NJ), for example, will be introducing a new line of cutting fluids based on vegetable oils. The company has always carried some vegetable-oil-based fluids, but this introduction represents a major investment in new chemistry for the 70-year-old company. "We feel it's going to position our products for the next 70 years," says Hangsterfer's Andrew Dubler.

The move involves risk, however. Vegetable-based cutting oils have been around for decades, but the metalworking industry has been reluctant to accept them. Besides being more expensive, the older vegetable-based chemistries were less stable than their petroleum-based counterparts. Cutting fluids based on them tended to decompose more rapidly in the sump than petroleum-based fluids.

Times are different now. Both the current economics and recent technical improvements are giving vegetable oils a new luster. "The oils that we're introducing have greater oxidation stability," says Dubler. "They maintain their original characteristics over longer periods in manufacturing processes like machining that put a lot of heat and pressure on them." Heat and pressure will eventually degrade any oil, even petroleum.

Although these vegetable-oil-based cutting fluids are still biodegradable, "they are fortified products that are not going to biodegrade in a machine's sump," says Dubler. And they have the added benefit of being made from biorenewable materials grown in the US.

Innovations in parts cleaning will be another way that the trend toward conservation will manifest itself. Stoelting LLC (Kiel, WI), for example, will introduce what it calls Liquid Lock technology for its conveyor-belt washers. This technology consists of thin, but solid, curtains of water falling in a controlled, laminar flow at the entrance and exit of the washer. These laminar liquid curtains do a better job of entrapping the steam and droplets atomized by the spray nozzles than rubber curtains do. When steam and atomized droplets hit them, they go back into solution and are recycled.

Recycling reduces operating costs in two ways. First, it allows less water and cleaning solution to escape into the environment, thereby reducing the amount of each that the machine consumes. Second, it saves energy by recovering heat that would otherwise be lost.

The savings can be significant. In the electronics industry, for example, the liquid curtain has saved as much as 70% in water, cleaner, and energy cost. Jim Timler of Stoelting predicts that the savings will be great in metalworking, but not quite as high as they were in electronics. The reason is that cleaning costs are already a little lower in metalworking than in electronics. In most metalworking applications, the requirements are less stringent. Most metalworking shops can get by with cheaper cleaners at lower concentrations, and can use regular tap water, instead of expensive deionized water.

Stoelting originally developed this technology for the electronics industry, where the curtains often retain solvents. Now that the technology is well established there, the company is adapting it for other industries to expand its product line. There is a height limitation, however. The parts must be less than 8" (203 mm) tall, because the laminar flow begins to degrade after that and become turbulent.

Laminar flow might be the key to savings in parts cleaning, but just the opposite is true for boosting the efficiency of oil coolers. In the case of a model that Alfa Laval (Warminster, PA) will be showing in its booth, turbulent flow unlocks the door to greater efficiency, lower cost, and environmental benefits. Most other shell-and-tube heat exchangers use laminar flow.

"Because of the high efficiency created by the turbulence, you wind up needing a slower flow for the cooling medium, which reduces the annual operating costs," explains Scott Seifert of Alfa Laval's Equipment Div. "This reduces your energy consumption." The turbulence also reduces fouling.

The company will also be showing a portable centrifuge that users can wheel up to their machines to clean their cutting fluids. After wheeling it into position, the operator connects it to one or more sumps and lets the unit run for a few hours. "The length of time and frequency of use depend on what you are machining and how clean the fluid needs to be," notes Tony Vecere of the company's Equipment Fluids and Utility Div.

He reports that the technology itself is not really new. Alfa Laval has been making centrifuges for cleaning cutting fluids for years, but they have been large units for automotive factories and other quite substantial machine tool facilities. "We've taken that larger technology and transformed it into a portable device that can be moved around in a smaller shop," he says.

Although not really an energy-saving device, the technology is related to the environmental theme at this year's pavilion in that it extends the life of cutting fluids, and reduces disposal costs. Not only does the device decrease the amount of spoiled fluid that needs to be discarded, but it also replaces cartridge filters. "We've created a machine that takes out oils and particulate without any type of filter element that you would ultimately throw away," says Seifert. Payback usually requires from six months to 1.5 years.—James R. Koelsch

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This article was first published in the August 2008 edition of Manufacturing Engineering magazine. 


Published Date : 8/1/2008

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