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Opening the door to pneumatic motion control

Changes in engineering and manufacturing have made complete proportional pneumatic control systems more affordable.

The price of Enfield’s LS-C10 controller has dropped 70%, from $564 to $169.20, and the LS-V25s proportional valve dropped 45%, from $721 to $396.60 – not including volume discounts.

Complete proportional pneumatic control systems have recently been made more accessible, according to Enfield Technologies, Trumbull, Conn. The company reviewed its engineering and manufacturing decisions and found new vendors to help make its products.

“We wanted to bring proportional pneumatics to new audiences,” says Ed Howe, Enfield Technologies’ president. “In motion control, that means a pneumatic actuator with intermediate positioning needs to break the $1000 price barrier. We beat that target by a wide margin, with the price of a basic system coming down from $1841 to $884 — a reduction of 52%.”

Finding qualified sources
Increased interest in the benefits of proportional pneumatics — such as high output forces, infinitely variable positioning, and ruggedness — let the company increase production and drive down costs over the last 18 months.

But it wasn’t just a matter of cranking out more product, explains Ken Barbee, the company’s production and lab manager. The company outsourced several in-house, specialized, precision manufacturing and assembly tasks to a handful of strategic vendors, and opened up much of the less-critical contract manufacturing to online competitive bidding. This in turn led to lower costs.

Online contract-manufacturing marketplaces, such as, have evolved from informational listings to mature services, says Howe. “At first we were suspicious, but those sites let us source broadly — more like a big company but without the large purchasing staff.”

Vendors and customers can post ratings and reviews on “It lets small companies like us get out of our local area — Connecticut happens to be an expensive place to source parts — and reach deeper into the contract manufacturing community throughout the U.S. and, in some cases, overseas.”

Finding vendors with specialized skills has also simplified the manufacturing process, notes Howe. For instance, precision-turned parts such as a proportional valve’s spool and sleeve are expensive, and getting the requisite quality virtually mandates using pricey aerospace vendors, he says.

Previously, Enfield relied on these high-end manufacturers to machine and finish the entire spooland- sleeve assembly, says Barbee. “To prevent finger- pointing among suppliers, we had to put full accountability on a single vendor, even if it meant requiring them to do machining or other operations they preferred to avoid.”

Enfield’s proportional valve and control electronics paired with a pneumatic cylinder and position sensor provided by partner companies makes up a basic positioning system. The same valves and control electronics used in motion control applications are also suitable for proportional pressure, flow, and force regulation applications. Proportional flow control and switching cost less than $500, and precision vacuum or pressure regulation is less than $650.

Expanding into new applications
Breaking into new applications will be easier with the lower prices, says George Haithwaite, sales and application engineering manager. He notes robotic surgery as an application with great interest in proportional pneumatics, but lower overall machine costs are needed to increase the market.

Mature markets will also benefit from more affordable components, he explains. “We see many customers in, say, packaging machinery, who want or need to stay with pneumatics, but require the features of electric drives. As machine builders strive to improve their designs — to have faster throughput, higher efficiency, and quick changeovers for different package size — a standard on-off pneumatics system won’t do.”

However, upgrading cylinders with position feedback sensors and adding proportional valves and controllers gives infinitely variable positioning. This capability gives the user a much higher level of control, Haithwaite says.

Proportional electromechanical systems are often viewed as lower cost components by most people, notes Howe. “But the low-end ones only travel to a limited number of predefined positions and have force, cycle, and life limitations,” he says. Proportional-pneumatic motion devices can travel to any position, take any new setpoint command in real time, follow complex force profiles, last longer, and transmit greater force from a given size. “Comparing apples to apples, infinitely variable positioning with proportional pneumatics was competitively priced, now it costs less,” says Howe.

“And in extreme environments like food processing, using a washdown- approved cylinder and sensor provides position and velocity control where, perhaps, electric drives are unwanted by the machine builder,” adds Haithwaite.

Enfield’s system is even stealing the limelight from conventional onoff pneumatics, particularly as production speeds increase, thereby increasing impact loads. “Admittedly, our valve is more expensive than a double-solenoid, on-off valve of the same size,” says Howe. “But to proprotect the cylinder, standard pneumatics needs cushions and shock absorbers, proximity sensors, and rod locks, and can’t change speeds without adjusting flow controls. Ours needs none of that.

“We’re still at a premium price, but now it’s not so high a premium for all the added functionality with fewer components. It’s worth it,” says Howe.

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