The Emerging Air Battle

The world of pneumatics is changing. Makers of pneumatic equipment face challenges from electric actuators, while users are beginning to take a closer look at the true cost of compressed air. But pneumatic equipment is not standing still, and is adding significant new features and capabilities. Several experts in the field provide some indication of where things will go in the future.

The Electrics Are Coming 
What is probably the biggest trend in the world of pneumatics is the encroachment of electric actuators into what had been pneumatics’ territory. Simple motion, such as pushing aside a package on a conveyor belt or locking a clamp on a machine, have long been done inexpensively and reliably with simple pneumatic cylinders — and to a large extent are still. But in other applications, particularly those in which close control over speed and/or position are required, electric actuators are coming increasingly into favor.

“As the price point on electric automation solutions continues to decrease and concurrently the power ratio increases,” says Jim Drennen, director of marketing at Tol-O-Matic, “electric becomes a viable alternative.” This, combined with users’ desire for integration and the more precise control available from electrics, is helping to drive the migration, he says.

Whither Servo-Pneumatics?
Pneumatics companies have tried to hold back the invasion of electrics. Some companies have experimented with various types of servo-pneumatic systems that tried to provide precision motion control by wedding position feedback devices with proportional valves and computer control. Some of these are still around, and some are still being developed, but most such attempts were stymied by the inherent compressibility of air.
Some years ago, Tol-O-Matic developed a system called PrecisionAire, which used a magnetic particle brake to help control the motion of a rodless cylinder. It claimed programmable position repeatability was up to 0.01 inch, but, says Drennen, air compressibility and complicated programming were problems, and the cost was too high. “I think it was a valiant attempt,” he says, “but in the end it didn’t prove very successful, because we had issues with overshoot because of air compressibility.”

This is not to say that servo-pneumatics is a lost cause; indeed, both Tol-O-Matic and Bosch Rexroth have, or are working on, servo-pneumatic products. On the other hand, several leaders in the pneumatics industry, including Parker Automation, are producing both electric and pneumatic equipment and are actively helping users make the transition.

Don’t Let Money Leak Out 
For a long time, people seemed to ignore the cost of compressed air. A main reason, suggests Drennen, “is that the people who see that costs are sitting in a different office from the people using that, and I don’t think those two ever meet an awful lot. So someone in charge of an operation and keeping a machine running isn’t always the same person paying the electric bill.”

Yet, says Phil O’Neill, product manager for standard products at Bosch Rexroth “it’s not so expensive if you stop throwing it away.” There are installations that leak so badly that the compressors run nearly all the time.
Fortunately there are multiple sources of advice and information on ways to cut the cost of air. Parker Hannifin cites a case in which identifying both audible and ultrasonic leak points at a customer plant determined that the facility was wasting roughly 36 percent of compressor capacity. Correcting the leaks eliminated the need for an additional compressor, saving $228,000. The company also points out the common (and wasteful) misconception that more pressure is always better, when in reality the only thing it increases is cost. While such a program can save substantial money, cautions Russ Strobach, vice president of marketing and business development for Parker Automation, it won’t do very much unless it’s comprehensive. You can, he says, “design better machines, stop a lot of leaks on the plant floor, but it all gets blown away through the roof of the compressor room unless you have someone who’s smart about compressors to make sure that you don’t lose all your savings through a relief valve or something.”

Smart Pneumatics 
One bright area for pneumatics is the addition of diagnostic functions, and multiple companies provide manifolds with digital communications capability. Pneumatic equipment, says Frank Langro, manager of the product measurement group at Festo, will increasingly provide “more intelligence, diagnostic information about the component itself as well as the overall system,” ranging from pressure to what type of leakage you might have in your component or system.” O’Neill reports that his company has integrated diagnostics into its latest generation of manifolds that extend down to checking each solenoid coil for open or short circuit. He cautions, however, that it’s possible to go overboard with diagnostics; when an industry group asked vendors for input on diagnostics, he says, they responded with such enthusiasm that the result was information overload. “You don’t want to be flooding your network constantly with bits and bytes just saying ‘I’m OK, I’m OK, I’m OK, I’ve got a problem,’” he says. Instead “you need to be able to set maybe one bit that says ‘I’ve got a problem,’ and then you can go dig into what the problem is.”

A Look Ahead
While electric equipment is making inroads, it’s doubtful that it could ever completely displace pneumatics. “There are still many things that will use pneumatics,” says Langro. “The cost of pneumatics is coming down too, because as the electromechanical systems encroach price-wise it drives the other down as well. There’s also miniaturization and costs going on in pneumatics as well, and that’s going to be there.” In addition, he says, manufacturers are working to broaden the technology from a simple two-position cylinder, finding ways to add position feedback devices at a reasonable cost. Still, he agrees, “These things are happening, but the higher growth is definitely in the electromechanical.”

Drennen believes that worldwide demand for pneumatic equipment will essentially track overall economic activity. “I don’t think its going to grow any faster or decline too much more than the worldwide production,” he says — to a large extent because of rapidly increasing demand in Asia. Much of that is caused by the emergence of a Chinese market, he explains. China, he says, is busy filling its own domestic demand. If there’s a slowdown in Asia, he says, we’re likely to see “Asian suppliers trying to figure out how to break into the US market.” In the US, on the other hand, sales are likely to be no better than GDP growth, and perhaps less than that.