The story is all too familiar. Your best customer places an important order for a custom-made product that is needed as soon as possible. The raw materials are there, and the job is set up and running fine when, suddenly, disaster strikes!

The story is all too familiar. Your best customer places an important order for a custom-made product that is needed as soon as possible. The company is even willing to pay rush charges to speed the delivery process. You give the company a firm delivery date and do not foresee any problem getting the job shipped out on time. The raw materials are there, and the job is set up and running fine when, suddenly, disaster strikes! Half-way through the production run, the machine grinds to a screeching halt and refuses to budge. That's exactly what happened to Lasercraft Inc., Fairfield, Ohio, manufacturers of precision laser-cut metal parts.

An Equipment Meltdown

Most of the country experienced scorching heat this summer where temperatures soared to record levels. For Lasercraft, June brought the expected heat wave. The building was uncomfortably warm, but production ran without a hitch. However, as the days pushed into mid-July, the temperatures continued to rise. The 90oF (32oC) days, combined with heat put out by its laser-cutting machine, took the temperature of the non-air-conditioned shop up over 100oF (38oC). Soon, the heat took its toll on the laser-cutting machine's electrical enclosures. The computer produced a lot of error messages and stopped the operation. Lasercraft tried numerous times to get the program to run with no success.

As it turned out, the main CNC circuit board failed and required shipment to Australia (the manufacturer's principle location) for repair. The situation worsened. It took three days to get a temporary replacement computer. On top of that, the heat in its free-standing control was shutting off the computer monitor. This "meltdown" left Lasercraft no choice but to move the job to its Cleveland location until the repairs could be made. The urgency to keep its good reputation and meet delivery times made finding the proper cooling product Lasercraft's first priority.

Jeff Hauck, general manager of Lasercraft, began searching the Internet for a solution. "Of course, I wanted to come up with something that was permanent, so this would never happen to us again," Hauck said. "Opening the panel doors wasn't an option due to safety concerns about having exposed electronics. Mounting panel fans made no sense because the temperature in the shop was too hot to provide cooling."

Exair's compressed air-powered cabinet cooler cools Lasercraft's control panel with 20oF (-6.67oC) air.

A Possible Solution

After reading about heat exchangers, he concluded they would be impractical because there was little difference between the hot cabinet temperature and the outside surroundings. He also had considered Freon-type air-conditioners similar to those on other panels in the Lasercraft building. Based on past experience, Hauck considered them "a constant maintenance project of their own" and, as a result, decided against them based on the ongoing hassle of keeping the filters clean and the Freon charged. Finally, he found Cincinnati-based Exair Corp., a company that manufactures a cabinet cooler that met all of Lasercraft's requirements.

Exair's cabinet coolers are powered with compressed air, and a vortex tube is incorporated to purge the enclosure with cold air. "After finding Exair on the Internet, I recall seeing their cabinet cooler. Honestly, I had my doubts that something so small could deliver the cooling we needed -- but was pleasantly surprised after installing it. The staff calculated the cooling capacity and told me there was a 30-day, no-risk guarantee. I figured I had nothing to lose, so I ordered it and it arrived the next day," Hauck said.

While Lasercraft was waiting on its repaired computer board, it outfitted the cabinet for its laser cutter with the UL listed cabinet cooler system. Lasercraft also had purchased a second NEMA 12 cabinet cooler system to mount on top of the monitor control panel. The cabinet cooler came with everything needed to get it up and running. For Lasercraft, numerous features -- including ease of installation, compact size, ready availability, maintenance-free design, quiet operation and low cost -- made Exair's cabinet cooler the best choice (see sidebar).

It took Lasercraft only a few minutes to install the cabinet cooler through a standard conduit knock-out punch on the top of its cabinet. Because there is built-in relief on the unit, it was not necessary to add any holes in the enclosure to get the hot panel air out. The compact footprint of the 2,000 BTU/hr cabinet cooler, measuring only 1.375" in diameter by 8" tall, permitted mounting with minimal space. A cold-air distribution kit incorporating vinyl tubing with adhesive clips permitted routing the cold air to those electronic components most susceptible to high temperature.

Beneficial Features

Most important to Lasercraft was that there were no moving parts to wear out, meaning the cabinet coolers were maintenance-free. The only requirement was clean, dry, oil-free compressed air at 80 to 100 psig. Exair's system provided a filter/separator for removing dirt and water from the compressed air to keep the inside of the enclosure contaminant-free. Because Lasercraft's compressor system was a few years old, the company also purchased an oil-removal filter to keep any oil in the compressed air from passing into the enclosure.

Both units purchased by Lasercraft included a thermostat control to maintain 95oF (35oC) inside each of the cabinets. This is accomplished with an electrical thermoswitch that actuates a solenoid valve, turning on the compressed air only as needed to minimize its use. The 95oF thermostat setting allows the enclosure temperature to stabilize well below the 104oF (40oC) limit of the electronic components inside without going extravagantly low, which would waste air. The thermostat accuracy is +/-2oF of that setting so there is not a risk of failure.

"It's hard to believe that you can get so much cooling out of one of those little tubes," said Hauck. "In the cool mornings, it never operates, but as the day heats up, the thermostat turns the cabinet cooler on and off in short bursts to maintain the temperature in the enclosure."

Lasercraft soon realized an additional benefit. In the past, it seemed that dust and smoke in the environment always seemed to infiltrate the electrical enclosures on many of its machines. It was typical to open the door of a machine and find a black, sooty mess covering the insides. The Exair cabinet cooler kept the enclosures sealed, preventing dirt and dust from getting inside.

"As a matter of fact, we have recently added one of Exair's NEMA 4 cabinet cooler systems to one of our CNC lathes just as a precaution, even though there is a Freon air-conditioner already on it. I've seen how gummed up those filters get with the coolant and dirt. I don't want this to happen again," Hauck said.

Lasercraft now considers these cabinet coolers to be a good insurance policy against the summertime heat conditions that had just cost them a significant amount of money.

Compressed air enters the vortex tube-powered cabinet cooler and is converted into two streams, one hot and one cold. Hot air from the vortex tube is muffled and exhausted through the vortex tube exhaust. The cold air is discharged into the control cabinet through the cold air distribution kit. The displaced hot air in the cabinet rises and exhausts to atmosphere through the cabinet air exhaust at a slight positive pressure. Thus, the control cabinet is both cooled and purged with cool, clean air. Outside air is never allowed to enter the control panel.

Costly Problem Fixed

"We learned an expensive lesson," said Hauck. "As a result of the electronics failure, it was necessary to move the balance of the job to our Cleveland facility. It slowed our productivity and surprised us with enormous repair costs and freight charges. It cost us nearly $15,000 to get our equipment back up and running."

Lasercraft Corp. has a customer base involved in the automotive, aerospace, construction and machine-tool industries. It cannot afford to keep customers waiting while it fixes summertime overheating problems in its electronic cabinets. Lasercraft desired a simple design, easy installation, low cost and a reliable unit to combat the common problem of summertime heat and downtime due to overheated electronic enclosures. Exair was able to meet these requirements and provide a solution to beat the heat.

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