Pneumatic valve terminals are a key element in the performance of many of today’s automated machines. They interface between the electronics – the software and controls, providing the intelligence – and the actuators and sensors driving the motion and sending feedback. Introduced 30 years ago, the valve terminal concept integrated electrical connections to the solenoids and feedback signals e.g. cylinder switches, moving the technology on from purely mechanical/pneumatic sub-bases. The time and cost savings were enthusiastically embraced by the machine building sector.
The technology has come a long way since then, with both the mechanical valve mountings and the electrical connectivity evolving through several iterations. However, Festo believed that there was further scope for improvement, to create a new type of valve terminal that would address the challenges machine builders are likely to face in the next five to ten years.
Continuous improvement
The next evolution involved the creation of one of Festo’s largest cross-function design teams. Their brief was for a ground-up rethink to create another true step change in valve terminal technology. Based on feedback from machine builders (see Figure 1 Checklist), it was clear that any radically new valve terminals needed to address both the mechanics/pneumatics and the electrical connectivity within a single platform, so both disciplines were embedded in the development team from the outset.
To maximise the benefit of the platform approach the team focused on creating a design that spanned from high-volume, low-cost, basic functionality to highly featured, technology rich options that addressed future technologies and specialist requirements in sectors previously seen as niches. The new prototype was dubbed VTUX, or Valve Terminal Universal “X”. The “X” in the type description signifies the ‘built-in flexibility’ to incorporate many new and innovative features in the coming months and years which will ensure its continued relevance in ever-changing automation environments.
The VTUX team developed software tools by comparing theoretical CAE models with thousands of hours of real-life pneumatic lab results to hone the accuracy of the software predictions and to provide the system developers with a uniquely powerful CAE software tool kit. This enabled the VTUX engineers to optimise production and material costs and CO2 usage during manufacture, while balancing these aspects against the need to supply higher flow rates in less space, increase the operating life expectancy and identify ways to improve the electrical (solenoid) energy efficiency.
Customer benefits
Cost savings for the customer are possible thanks to a rationalisation of components. On the latest Festo 10mm wide solenoid valves the limit to the maximum flow rate isn’t the valve (as it used to be) but the fittings and therefore tubing that can fit within the footprint. As a result, one of the obvious cost savings was to offer one valve body size with two different sub-bases. This enables the customer to specify the higher flow option when it is required, for larger diameter actuators or faster cycle rates. Conversely, they can save on the overall width of the terminal and reduce unnecessary air consumption by using smaller diameter tubing where this is sufficient.
Electrical optimisation is another benefit. For machine builders, this is usually a matter of cost, speed of integrating into the control architecture and ease of commissioning and diagnostics. For the end-user, OEE (Overall Equipment Efficiency) is the most typical measurement of machine performance and reliability, with reduction of downtime and consistent performance (influencing output quality) as key influencers. The impact on energy consumption of the individual solenoid valve coils and reaction times of the cylinders is minimal compared with the compressed air passing through the valves, but it still made sense to reduce solenoid power drain overall, reducing the size and current capacity of panel mounted power supplies, and to minimise valve actuation times.
Ease of connectivity is the third major benefit that the new valve terminal design addresses. How machine builders connect between the control system and the machine level sensors and actuators is critical: it is where the biggest savings or the biggest losses are made. Ideally, they can simply integrate between standard control hardware, navigate the specialities of their application, and connect to motors and drives quickly and easily.
To deliver this benefit required simultaneous development of the valve terminal and an electrical connectivity product range, called Festo AP (Automation Platform).
Hybrid solution
The Festo AP supplies a lower cost but fast and powerful connection way for the last few metres on a machine. It doesn’t compete with the likes of IO-link or Ethernet technologies but seamlessly collaborates with them to provide cross protocol connectivity and transparency. The user experience for the software and controls engineers that program and commission new machines was a key focus here. This is achieved by supplying simple intuitive user function blocks and integrated documentation (online and digital for incorporation in packages such as EPLAN).
The Festo AP addresses key needs of both serial and special purpose machine builders. The system enables machine builders to swap the PLC they are using to meet the specification of their customers whilst keeping up to 90% of the remote IO [RIO] field and cabinet level components common. This makes it easier, and lower cost, to support a range of machines and creates an ideal platform for a range of machines based on common technology and components.
The AP system is a hybrid approach, it delivers interconnecting modular and decentralised IOs on a scalable, flexible, and powerful communication backplane. The designers’ brief was to address three key factors – Performance, Flexibility and Cost. They created a modular system of robust digital RIO components that can be field, or cabinet mounted, alone or in combination with industry leading pneumatic valve solutions. The system uses a single field bus node module as a header, which is networked to a broad range of input, output, and pneumatic solenoid valve manifold options.
The AP system and its components can be flexibly arranged without topology or space restrictions to fit the machine layout. This comes at a lower cost than using multiple proprietary field bus nodes and yet is still easy to address and completely visible within the PLC controls. The Festo Automation Suite software is free of charge. Module connections are made using pre-formed plug-in cables, again saving time and cost. IO-Link is incorporated within the system, enabling users to make full use of its component parametrisation and data collection capabilities.
The story continues
The ongoing evolution of valve terminals reflects the automation industry's dedication to improving machine performance and efficiency. Through continuous innovation, manufacturers like Festo are providing solutions that not only meet the current needs of machine builders but also anticipate future challenges, ensuring that valve terminals remain an essential element in the landscape of automation. The latest iteration of the valve terminal, exemplified in Festo’s new VTUX valve terminal and the AP connectivity platform, provides machine builders with the opportunity to save costs and increase their machines’ performance individually or, most powerfully, when combined. New components and features are being added to the range every month, so this is a story of continuous evolution.