By Ed Sullivan

Without optimum air compressor technology, shops face costly rework, high maintenance and replacement costs, exorbitant downtime — and very unhappy customers.

Compressed air represents more than 10 percent of total industrial costs.

Given the current technological age, preferences for a specific air compressor design might seem a like an afterthought. Yet, for businesses that are highly dependent on compressed air, choosing the right compressor technology may be crucial.

In the woodworking business, for example, the continuous availability of unfaltering, high-volume compressed air is vital to support various tools as well as the filtered breathing air system.

“When the air goes down, the woodworking shop is dead in the water,” says Stuart Silverman, president of Lans Co., Glendora, CA. “Without the right compressor technology, some of our woodworking and finishing shop customers would be down every week, waiting for service technicians to get them back up and running.”

According to Silverman, who has more than 40 years in the industry, to have a wood shop customer with air compressor problems is unacceptable. Ultimately, it was also unacceptable to their customers. Both wanted not only high-quality, but timely craftsmanship, such as for new cabinets as well as repair work. Since woodworking is a continuous flow, air system downtime often disrupts an entire shop, sometimes for days.

“This situation becomes intensified by the woodworking shop’s need for clean air, including providing a pure supply to the paint/varnish spray systems and tools as well as the breathing system that delivers fresh air via respiratory masks to spray finish technicians,” explains Silverman.

Choosing the Right Technology

Over the years, many woodworking shops had tried several types of air compressor systems, including piston-driven models and rotary screw designs.

“Everybody is familiar with the old piston style of compressor,” says Silverman, “It’s a fairly simple concept, a piston running up and down and turning a crankshaft. But of course that motor also relies on intake and exhaust valves, which tend to wear and then leak. Once that happens, oil can get into the air system. That is definitely a drawback to the purity of the system and causes maintenance headaches.”

Many woodworking shops have used rotary screw compressors, but were disappointed with the inherent volumetric and efficiency problems due to the “blow hole” and air leakage characteristics of those compressors. Moreover, in order to make up for inefficiencies and keep up air volume, designers of rotary screw compressors incorporate higher speed, which is detrimental to service life.

“Also, the pressure buildup at the end of the screws is so high and so hot, it burns out the bearings,” says Silverman. “Plus, they could never keep the back end of the screws together because of the axial thrust; so, they just kept adding more and bigger bearings. Some shops have had screw compressors blow up because of the extreme pressure point at the end of the screws.”

Silverman says more and more woodworking shops are changing over to rotary vane compressors, a more sophisticated technology with one major moving part. The rotary vane design is far more efficient and cleaner than the piston or rotary screw technologies. Also, the vanes are held outwardly by centrifugal force. A film of oil between the blades and the stator (housing) wall forms a practically perfect seal. Importantly, the performance of a rotary vane compressor does not degrade over time. During rotation, the vanes slide on an oil film, preventing direct contact with the internal surface of the stator. This means there is virtually no wear on the vanes.

Simplifying Service

Rotary vane compressors, such as the Mattei line offered by Lans Co., are easier to maintain and service, requiring fewer repairs and longer intervals than their piston or rotary screw counterparts. Assembly and dismantling of the compressor can be carried out quickly by using standard tools. Easy dismantling of the wood working machinery into subassemblies also makes fault diagnosis easy.

“Our customers don’t normally perform any service on these compressors,” Silverman says. “When a customer calls and says they have an air problem, we provide quick response and knowledgeable service.”

Silverman adds that many of his customers want a partner when it comes to air systems. He says it is frustrating for them to deal with multiple vendors on multiple systems that are integrated.

“They can give you the runaround,” he explains. “For instance, they might have an air dryer down and the air dryer technician points to the air compressor and says that’s where the problem is. The woodworking shop doesn't want vendors passing the buck like that. They want an air specialist to take care of it all. And having that kind of relationship has usually paid off.”

Plus Savings

While the cost of electric power needed to drive its wood working machinery is not a major issue with some users, excessive use of power may be a significant cost that is often swept under the rug. For example, older models of compressors often cause a spike in the electric power load during peak usage periods.

“In some businesses, such as body shops, the air compressor is the biggest piece of equipment,” says Silverman. “Relatively speaking, it can cause a lot of expense. With the Mattei compressors, we install a ‘part winding start’ at no extra charge. That allows the motor to ramp up to speed, which lowers the usage spike during peak periods. By making the peak smaller, we can lower a sizable electric bill. The savings will be more than enough to justify the cost of a high-efficiency air compressor. Shops that are running 60 horsepower compressor motors could save as much as $1,000 per month."

Ed Sullivan is a technology writer based in Hermosa Beach, CA.

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