Air Dryer Adds Hundreds of Dollars of Production/Week on High-Precision Slitting Machines

At Metlon Corp., a new air dryer paid for itself after only a few months by completely solving a rust problem and giving the company hundred dollars worth of additional production time each week on its high-precision slitting machines. In the past, water in compressed air lines caused valves within the machines to rust and stick. At least three times a week one of the slitting machines was down for an hour while the valves were cleaned or replaced. The new air dryer uses advanced membrane separation technology instead of refrigerants or freon to remove 99.9 percent of the moisture from the compressed air system. It has completely eliminated downtime due to rust. Metlon also installed air filtration technology from the same vendor on a cutting application that formerly required nitrogen to clean the cut pieces. The dryer made it possible to switch to regular compressed air, saving the cost of the nitrogen and paying for itself in eight months.

Founded in 1947, Metlon Corp. of Cranston, Rhode Island provides high-precision slitting capabilities for a wide range of materials including: plastic films, papers, metal foils, impregnated fabrics, and laminations of these and other flexible materials. The company's custom-built machines can hold tolerances of ±.001 inch and in some situations even closer. The company will slit to widths using either the English or the metric system. The machines can slit rolls up to 54 inches wide, with finished slit widths down to .0078 inch. This is just three times the width of a human hair. In one typical application Metlon gang slits 278 ends of polyester film simultaneously to 0.0078 inch wide and winds each end on a separate traversed spool. For jobs requiring very high accuracy, the slit product is measured with a Zygo laser micrometer. The following is a partial list of the industries which Metlon serves: aeronautical, automotive, cable, electrical, electronic, film, furniture, health services, magnetic tape, packaging, personal safety, pharmaceutical, rubber, textile, wild game control, and wire. Metlon will also develop special slitting and winding machinery for new products.

Compressed Air Sensors
One of the competitive advantages of Metlon's slitting machines is extremely accurate registration in very narrow width slitting. For example, one job involved a 16 mm (0.630 inch) wide film with 0.030-inch wide numbers printed down the center. The customer required that the film be slit to a final width of 0.040 inch and that the printed numbers be kept in the center of the finished width. The customer had asked a number of other companies to do this work and was told it was impossible. Metlon was successful because its machines are equipped with highly accurate edge guides that direct the material onto the machine. These guides are optical and pneumatic devices.

Pneumatic edge guides use air from the plant's main compressed air system. In the past, moisture built up in the air lines, causing valves and solenoids in the edge guides to rust. "It was a constant problem," says Wayne Etchells, vice president at Metlon. "At least every other day, one of the machines was down while we took apart and lubricated the valves. And in some cases, we had to replace the valves." The maintenance took about one hour, at an estimated cost of $75 per hour in lost productivity.

One possible solution to this problem was a refrigerated air system that dried the air as it cooled it. This was an expensive option, however, costing between $5,000 and $6,000. Operating costs would also be high due to the electricity needed to run the system. Another option was presented by a salesperson from Parker Hannifin Corporation's Filtration and Separation Division, Tewksbury, Massachusetts, who suggested a new type of compressed air dryer. The Balston Membrane Air Dryers he demonstrated uses membrane filter technology. "He guaranteed it would work, so we gave it a try," says Etchells.

Metlon installed a Balston Model 76-50-35 Membrane Air Dryer, which produces a flow rate of 50 SCFM. It cost approximately $2,600 including installation. Compressed air goes into the Balston system but prior to entering the membrane drying portion of the system, the air passes through two high efficiency coalescing filters. The filters remove water droplets and particulate contamination with an efficiency of 99.99% at 0.01 micron. Next the air passes into Balston dehydration membranes. These consist of bundles of hollow membrane fibers, each permeable only to water vapor. As the compressed air passes through the center of these fibers, water vapor permeates the walls of the fiber, and dry air exits from the other end. A small portion of the dry air (regeneration flow) is redirected along the length of the membrane fiber to carry away the moisture-laden air that surrounds it. This moisture-laden sweep gas is vented to the atmosphere while the remainder of the dry air is piped to the pneumatic edge guides and other applications in the plant that use compressed air. The dryer delivers air with a dewpoint of 35 degrees F.

The Balston Membrane Air Dryer is designed to operate continuously, 24 hours per day, 7 days per week. The only maintenance required is changing the prefilter cartridge once every 6-12 months. Replacements cost about $40 and the time required to change the cartridge is approximately 5 minutes. No electrical supply is required to use these dryers, which makes them much less expensive to operate compared to refrigerants. Another advantage over refrigerant air drying is that the Balston method does not produce condensate. An average 100 CFM compressor system can produce up to 1,800 gallons of oily condensate per year, adding a disposal cost to the operation as well.

The installation of the air dryer solved the problem Metlon was having with rust in the edge guides. "This new type of dryer was just what we needed to eliminate problems with water building up in compressed air lines. Since the day we installed it we haven't had a single problem with rust," says Etchells. "This has totally eliminated downtime. At an estimated rate of $75 per hour for the production rate of the machines, the dryer saves us more than $200 each week. At that rate, it paid for itself in just over three months."

Air Filter Application
When the Parker Hannifin representative came back to see how the dryer was working, he noticed that Metlon was using nitrogen in a particular cutting application. The machine was a core cutter and the job was for one of Metlon's customer in the electronics industry. After the cores were cut, Metlon used nitrogen to clean them of dust from the cutting process. "These cores are reels that eventually go into a Class-10 clean room, so they have to perfectly free of dust," explains Etchells. "We were using compressed nitrogen to do this because compressed air, even though we had gotten it free of moisture with the air dryer, still had particulates. It wasn't clean enough to use for this job." Metlon had compressed nitrogen delivered daily for this application at a cost of about $200 per month.

After they explained the situation to the Parker Hannifin representative, he suggested an alternate solution – an air filter downstream from the air dryer that would trap the particulates. He recommended the A 15/80, which costs $1,600. Metlon installed downstream of the Balston air dryer in the line coming to the cutting machine. "The filter removes 99.9 percent of the impurities from the compressed air, making it pure enough to clean those reels," says Etchells. The company stopped its nitrogen deliveries completely, and that saving paid for the air filter in eight months.

Metlon has been using the Balston air dryer since the fall of 1998 and the air filter since early 1999. Both products have performed perfectly. "We have had no problems with either of them," says Etchells. "They work just as advertised. Our compressed air system is now completely dry and clean at a very reasonable cost. And we gain at least three hours of production time each week by not have to shut down to clean rusted valves. To us that is worth hundreds of dollars, making these products an excellent investment."

For additional information on contact Parker Hannifin Corporation, Filtration and Separation Division, 242 Neck Road, Haverhill, MA 01835. Tel: 800-343-4048 Fax: 978-858-0625 Web site: www.parker.com/balston.