Extract from the magazine "Hydraulics & Pneumatics" from February 1998

Future uncertain

Not even the traditional manifolded poppet valve is safe as cutting edge innovators seek to produce compact yet flexible alternatives. So far, these intelligent electro-pneumatic derivatives number three in UK: the airbox, developed by Kuhnke and now marketed by Siemens, Bosch, IFM Electronic and Compair Maxam; the compact performance valve terminal (CPVT) from Festo; and most recently, SMC's SY cassette manifold, which like the Festo system combines slice shaped valves in an ultra compact rack.

Not suprisingly, those behind these new products believe that the typical electropneumatic valve manifold is in decline as fluid power users seek further reductions in the size of their automation systems. Brod Bass, UK managing director at Kuhnke, says: "I'm not sure there is still a huge market for manifold valves - because of their built-in redundancy."

But this conclusion is out of date counters Richard Roebuck, UK marketing manager for Parker Pneumatic. The days of users being stuck with large manifold blocks designed to carry at least eight valves, whether they required that many or not, are over; he suggests. I!you can now have a modular Lego type system where one or two valves can be added at a time."

Players on either side of the manifold block divide agree that the process of electropneumatic valve miniaturisation has some way to run." Of course you have to deliver enough air to the actuator but I think we are at the start of this miniaturisation curve," says Bass. The tooling that will manufacturer smaller valves is already with us, he suggests. "lnvesting in this tooling is expensive; we have done it but I'm not sure how many other pneumatic equipment producers are prepared to."

This scepticism is echoed by Jerry Knight, Festo's marketing manager, who says that a part of the problem is that potential users of new pneumatic technology are unwilling to pay price premiums for excellent automation product. He points out that his company's groundbreaking CPVT system on I y came about by ploughing 7 per cent of turnover back into R&D, and that such investment needs to be met with an end-user market that is receptive to new ideas. He has his doubts. UK industry "is unwilling to invest in new technology and has an obsession with a low labour rate economy."

Bass concurs: "The automotive industry, for example, is very closed to new ideas. They are now using fewer and fewer suppliers."

But the battle to persuade such significant end user markets must continue, says Richard Oakey at Crouzet. "Until now, we have always been able to seIl pneumatics as a low cost alternative to purely electrical systems. This is no longer true; we now have to sell electropneumatics as a good engineering solution."

As well as the understandable reluctance amongst pneumatics players to invest in the tooling required to produce innovative product - given the conservatism of many end users - there are other limiting factors in the miniaturisation of valve islands. "Partly its a question of getting the necessary electrical equipment on the block. This requirement will limit overall miniaturisation," explains Oakey.

"Valves now consume around O.5W, compared to 4.5W not too long ago, which obviously cuts the size of the solenoid and therein the overall unit; " says Knight. "With our CPVT design, the individual valves are really quite small, what takes up the room is the fittings."

Martin Eadon, the senior product analyst at SMC, concurs. "The limiting pneumatic factor will be the fittings in the pipework running between valve and actuator. These will increasingly inhibit air flow as valves reduce. "

The key to ensuring that the desirable objective of smaller valves is not stymied by such peripheral considerations is feit to be greater integration: both between pneumatic components and electronics.

Richard Roebuck is adamant: "There is still some mileage to go in bringing the electropneumatic together. For example: we might develop an actuator which contains both a fieldbus link and an airbox or airbox type valve - as part of an integral unit."

Knight agrees: "I think we are not too far off the time where we will see an intelligent actuator - containing a smart valve and bus terminal. " In terms of actuator developmement, he feels that designers are somewhat hindered by VDMA and ISO standards which forces them to work "to the lowest common denominator. We at Festo are building cylinders which are compatible with these standards, rather than copies of them."

Oakey says that pneumatic designers need to firstly focus greater attention on integration with electronics. " At the moment we have discrete electrical and pneumatic outputs, but we could move to a position where they are on the same block. A lot of pneumatic players still see the electrical as simply an add-on."

Oakey says that pneumatic designers need to firstly focus greater attention on integration with electronics. " At the moment we have discrete electrical and pneumatic outputs, but we could move to a position where they are on the same block. A lot of pneumatic players still see the electrical as simply an add-on."

Roebuck says: "For us, new installations are almost all served using our Valvetronic electropneumatic range."

Bass draws on his experience at last November's Manufacturing Week exhibition. " Of those who visited the stand, around two thirds were interested in our small electro-pneumatic valves. ASI was the next most popular, while our larger pneumatic valves created very little attention."

ASI

ASI, or actuator-sensor interface, is a low level fieldbus specifically designed to link the physical level of modestly sized hierarchical networks. One yellow ASI cable can link groups of valve islands across a maximum 100m distance. This fieldbus is designed complement those protocols designed to link across the PLC layer:, such as Profibus, Inter-bus-S and Devicenet.

Oakey points out that although ASI costs more to install across a typical electropneuamtic than if valves were hard wired, the price of future system upgrades is immediately reduced should the fieldbus path be chosen.

ASI certainly received positve reviews from those I spoke to. Roebuck says: "ASI is a wonderful cabling system suited to digital sequential control which is how pneumatics works."

"Hard wiring is in terminal decline," adds Bass." ASI is still the most exciting electropneumatic product out there at present, partly because it is IP67 compatible."

Eadon, although enthusiastic about ASI's future, feels it full potential will be lost unless electronic communication as a whole tightens up its act. "Bridging systems that link different levels of fieldbus protocol, such as Profibus and ASI, are becoming available and should be more widely used. We need to establish twoway fieldbus communication, so that more information passes from the ASI layer back up to the PLC network."

Such a system will help reduce wiring clutter at the PLC level as more communications intelligence is downloaded and routed through the ASI bus, says Knight. "You can still find yourself stuck with a lot of cabling nodes using something like Profibus, which ASI could help to strip out."

The reason such vertical fieldbus communication is not more firmly established in Britain is our marked reluctance to invest in fieldbus technology, despite an often sophisticated marketing effort running over the past five years.

"There is a lot of talkabout fieldbus in UK but not much action," says Roebuck. "Looking at how we compare with Europe, relative uptake is around 4:1 in their favour." Others agree.

But ASI's simplicity and relative low cost could help correct this imbalance, according to Jerry Knight. II ASI represents a relatively low level investment in low risk areas of the manufacturing plant. As such, its a good 'toe-in-thewater' fieldbus."

Like Jerry Knight, Bass is adamant about the core reason behind UK plc's lack of enthusiasm for fieldbus. "It is balance sheet driven rather than technology driven. We need to look at the economic cycle and I would say the pneumatics market is currently in recion."

Bass suggests that once potential customers have money to spend, manufacturers of pneumatic equipment will in turn plough more into their own R&D. "Research into new products can be delayed by up to three years if the market is not ready to receive them. The cycles need to balance."