Prices Drop for Proportional Pneumatics

May 3, 2010
Design and manufacturing innovations make high-end pneumatic positioning more affordable.
Enfield Technologies,

Thanks to some innovative engineering and revamped manufacturing, Enfield Technologies, Trumbull, Conn., ( is making complete proportional pneumatic control systems more affordable.

“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 $1,000 price barrier. We beat that target by a wide margin, with the price of a basic system coming down from $1,841 to $884 – a reduction of 52%.”

During the last 18 months, Enfield Technologies has revised its sourcing and manufacturing processes. 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.

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

What’s interesting is how 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.” On specifically, vendors and customers can post ratings and reviews. “We’re taken very seriously because we have a reputation for actually awarding contracts, rather than using it for price discovery to negotiate elsewhere. For small companies, it’s transformational, because it lets 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.”

“We don’t always choose the lowest bidder,” cautions Barbee. “We interview firms, look for certifications, and request samples to ensure the shops are capable. As a result, we’re finding a good match between low price and high quality.”

The company is also taking greater advantage of the specialized skills of individual vendors, 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 spool-and-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, for reasons like low margins or the need for new equipment.

“With a broader vendor network, we have successfully broken down the process among multiple suppliers. Now, we can capitalize on each vendor’s strengths and get lower prices,” says Barbee. For a recently developed product, the company now buys high-precision spool-and-sleeve components from Taiwan and is getting better quality at an 80% lower price. Parts are then sent to a domestic strategic partner for final processing and assembly of the valve.

Enfield has also reengineered several key products to improve performance and reduce costs, and they have automated more test and assembly operations. Lower commodity prices have helped, but the company expects these to rise again. Added up, this has let the company reduce prices by an average of 42% on its primary components.

A basic positioning system includes Enfield’s proportional valve and control electronics paired with a pneumatic actuator and position sensor provided by partner companies. The same valves and control electronics used in motion control are also suitable for proportional pressure, flow, and force regulation applications. Proportional flow control and switching are less than $500, and precision vacuum or pressure regulation is below $650.
Lower prices will open new markets, says George Haithwaite, sales and application engineering manager. He notes robotic surgery as a market with great interest in proportional pneumatics, but lower overall machine costs are needed to scale-up the market.

Revised pricing will also impact mature markets, he explains. “We see a large number of customers, say in packaging machinery, who want or need to stay with pneumatics, but require the features of electric drives. As machine builders strive to improve their machines – to have faster throughput, higher efficiency, and quick adaptation for changes in package size – a standard on-off pneumatics system can’t do that.”  However, upgrading cylinders with position feedback sensors and adding proportional valves and controllers gives infinitely variable positioning capability – making all this possible. “The user now gets a much higher level of control,” he says.

Many people view proportional electromechanical systems as lower cost, notes Howe. “But the low-end ones only travel to a limited number of predefined positions, and have force 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 produce more force from units of the same size.  “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 on-off pneumatics, particularly as production speeds increase and components and equipment see higher impact loads. “Admittedly, our valve is more expensive than a double-solenoid, on-off valve of the same size,” says Howe. “But to protect 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 a very affordable premium for all the added functionality with fewer components. It’s worth it,” says Howe.

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